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• How do I stop and repair a RAID 5 array that has failed and has I/O pending?

  - by Ben Hymers

  The short version: I have a failed RAID 5 array which has a bunch of processes hung waiting on I/O operations on it; how can I recover from this? The long version: Yesterday I noticed Samba access was being very sporadic; accessing the server's shares from Windows would randomly lock up explorer completely after clicking on one or two directories. I assumed it was Windows being a pain and left it. Today the problem is the same, so I did a little digging; the first thing I noticed was that running ps aux | grep smbd gives a lot of lines like this: ben 969 0.0 0.2 96088 4128 ? D 18:21 0:00 smbd -F root 1708 0.0 0.2 93468 4748 ? Ss 18:44 0:00 smbd -F root 1711 0.0 0.0 93468 1364 ? S 18:44 0:00 smbd -F ben 3148 0.0 0.2 96052 4160 ? D Mar07 0:00 smbd -F ... There are a lot of processes stuck in the "D" state. Running ps aux | grep " D" shows up some other processes including my nightly backup script, all of which need to access the volume mounted on my RAID array at some point. After some googling, I found that it might be down to the RAID array failing, so I checked /proc/mdstat, which shows this: ben@jack:~$ cat /proc/mdstat Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] md0 : active raid5 sdb1[3](F) sdc1[1] sdd1[2] 2930271872 blocks level 5, 64k chunk, algorithm 2 [3/2] [_UU] unused devices: <none> And running mdadm --detail /dev/md0 gives this: ben@jack:~$ sudo mdadm --detail /dev/md0 /dev/md0: Version : 00.90 Creation Time : Sat Oct 31 20:53:10 2009 Raid Level : raid5 Array Size : 2930271872 (2794.53 GiB 3000.60 GB) Used Dev Size : 1465135936 (1397.26 GiB 1500.30 GB) Raid Devices : 3 Total Devices : 3 Preferred Minor : 0 Persistence : Superblock is persistent Update Time : Mon Mar 7 03:06:35 2011 State : active, degraded Active Devices : 2 Working Devices : 2 Failed Devices : 1 Spare Devices : 0 Layout : left-symmetric Chunk Size : 64K UUID : f114711a:c770de54:c8276759:b34deaa0 Events : 0.208245 Number Major Minor RaidDevice State 3 8 17 0 faulty spare rebuilding /dev/sdb1 1 8 33 1 active sync /dev/sdc1 2 8 49 2 active sync /dev/sdd1 I believe this says that sdb1 has failed, and so the array is running with two drives out of three 'up'. Some advice I found said to check /var/log/messages for notices of failures, and sure enough there are plenty: ben@jack:~$ grep sdb /var/log/messages ... Mar 7 03:06:35 jack kernel: [4525155.384937] md/raid:md0: read error NOT corrected!! (sector 400644912 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389686] md/raid:md0: read error not correctable (sector 400644920 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389686] md/raid:md0: read error not correctable (sector 400644928 on sdb1). Mar 7 03:06:35 jack kernel: [4525155.389688] md/raid:md0: read error not correctable (sector 400644936 on sdb1). Mar 7 03:06:56 jack kernel: [4525176.231603] sd 0:0:1:0: [sdb] Unhandled sense code Mar 7 03:06:56 jack kernel: [4525176.231605] sd 0:0:1:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE Mar 7 03:06:56 jack kernel: [4525176.231608] sd 0:0:1:0: [sdb] Sense Key : Medium Error [current] [descriptor] Mar 7 03:06:56 jack kernel: [4525176.231623] sd 0:0:1:0: [sdb] Add. Sense: Unrecovered read error - auto reallocate failed Mar 7 03:06:56 jack kernel: [4525176.231627] sd 0:0:1:0: [sdb] CDB: Read(10): 28 00 17 e1 5f bf 00 01 00 00 To me it is clear that device sdb has failed, and I need to stop the array, shutdown, replace it, reboot, then repair the array, bring it back up and mount the filesystem. I cannot hot-swap a replacement drive in, and don't want to leave the array running in a degraded state. I believe I am supposed to unmount the filesystem before stopping the array, but that is failing, and that is where I'm stuck now: ben@jack:~$ sudo umount /storage umount: /storage: device is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) It is indeed busy; there are some 30 or 40 processes waiting on I/O. What should I do? Should I kill all these processes and try again? Is that a wise move when they are 'uninterruptable'? What would happen if I tried to reboot? Please let me know what you think I should do. And please ask if you need any extra information to diagnose the problem or to help!

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• What free space thresholds/limits are advisable for 640 GB and 2 TB hard disk drives with ZEVO ZFS on OS X?

  - by Graham Perrin

  Assuming that free space advice for ZEVO will not differ from advice for other modern implementations of ZFS … Question Please, what percentages or amounts of free space are advisable for hard disk drives of the following sizes? 640 GB 2 TB Thoughts A standard answer for modern implementations of ZFS might be "no more than 96 percent full". However if apply that to (say) a single-disk 640 GB dataset where some of the files most commonly used (by VirtualBox) are larger than 15 GB each, then I guess that blocks for those files will become sub optimally spread across the platters with around 26 GB free. I read that in most cases, fragmentation and defragmentation should not be a concern with ZFS. Sill, I like the mental picture of most fragments of a large .vdi in reasonably close proximity to each other. (Do features of ZFS make that wish for proximity too old-fashioned?) Side note: there might arise the question of how to optimise performance after a threshold is 'broken'. If it arises, I'll keep it separate. Background On a 640 GB StoreJet Transcend (product ID 0x2329) in the past I probably went beyond an advisable threshold. Currently the largest file is around 17 GB –  – and I doubt that any .vdi or other file on this disk will grow beyond 40 GB. (Ignore the purple masses, those are bundles of 8 MB band files.) Without HFS Plus: the thresholds of twenty, ten and five percent that I associate with Mobile Time Machine file system need not apply. I currently use ZEVO Community Edition 1.1.1 with Mountain Lion, OS X 10.8.2, but I'd like answers to be not too version-specific. References, chronological order ZFS Block Allocation (Jeff Bonwick's Blog) (2006-11-04) Space Maps (Jeff Bonwick's Blog) (2007-09-13) Doubling Exchange Performance (Bizarre ! Vous avez dit Bizarre ?) (2010-03-11) … So to solve this problem, what went in 2010/Q1 software release is multifold. The most important thing is: we increased the threshold at which we switched from 'first fit' (go fast) to 'best fit' (pack tight) from 70% full to 96% full. With TB drives, each slab is at least 5GB and 4% is still 200MB plenty of space and no need to do anything radical before that. This gave us the biggest bang. Second, instead of trying to reuse the same primary slabs until it failed an allocation we decided to stop giving the primary slab this preferential threatment as soon as the biggest allocation that could be satisfied by a slab was down to 128K (metaslab_df_alloc_threshold). At that point we were ready to switch to another slab that had more free space. We also decided to reduce the SMO bonus. Before, a slab that was 50% empty was preferred over slabs that had never been used. In order to foster more write aggregation, we reduced the threshold to 33% empty. This means that a random write workload now spread to more slabs where each one will have larger amount of free space leading to more write aggregation. Finally we also saw that slab loading was contributing to lower performance and implemented a slab prefetch mechanism to reduce down time associated with that operation. The conjunction of all these changes lead to 50% improved OLTP and 70% reduced variability from run to run … OLTP Improvements in Sun Storage 7000 2010.Q1 (Performance Profiles) (2010-03-11) Alasdair on Everything » ZFS runs really slowly when free disk usage goes above 80% (2010-07-18) where commentary includes: … OpenSolaris has changed this in onnv revision 11146 … [CFT] Improved ZFS metaslab code (faster write speed) (2010-08-22)

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• nginx: How can I set proxy_* directives only for matching URIs?

  - by Artem Russakovskii

  I've been at this for hours and I can't figure out a clean solution. Basically, I have an nginx proxy setup, which works really well, but I'd like to handle a few urls more manually. Specifically, there are 2-3 locations for which I'd like to set proxy_ignore_headers to Set-Cookie to force nginx to cache them (nginx doesn't cache responses with Set-Cookie as per http://wiki.nginx.org/HttpProxyModule#proxy_ignore_headers). So for these locations, all I'd like to do is set proxy_ignore_headers Set-Cookie; I've tried everything I could think of outside of setting up and duplicating every config value, but nothing works. I tried: Nesting location directives, hoping the inner location which matches on my files would just set this value and inherit the rest, but that wasn't the case - it seemed to ignore anything set in the outer location, most notably proxy_pass and I end up with a 404). Specifying the proxy_cache_valid directive in an if block that matches on $request_uri, but nginx complains that it's not allowed ("proxy_cache_valid" directive is not allowed here). Specifying a variable equal to "Set-Cookie" in an if block, and then trying to set proxy_cache_valid to that variable later, but nginx isn't allowing variables for this case and throws up. It should be so simple - modifying/appending a single directive for some requests, and yet I haven't been able to make nginx do that. What am I missing here? Is there at least a way to wrap common directives in a reusable block and have multiple location blocks refer to it, after adding their own unique bits? Thank you. Just for reference, the main location / block is included below, together with my failed proxy_ignore_headers directive for a specific URI. location / { # Setup var defaults set $no_cache ""; # If non GET/HEAD, don't cache & mark user as uncacheable for 1 second via cookie if ($request_method !~ ^(GET|HEAD)$) { set $no_cache "1"; } if ($http_user_agent ~* '(iphone|ipod|ipad|aspen|incognito|webmate|android|dream|cupcake|froyo|blackberry|webos|s8000|bada)') { set $mobile_request '1'; set $no_cache "1"; } # feed crawlers, don't want these to get stuck with a cached version, especially if it caches a 302 back to themselves (infinite loop) if ($http_user_agent ~* '(FeedBurner|FeedValidator|MediafedMetrics)') { set $no_cache "1"; } # Drop no cache cookie if need be # (for some reason, add_header fails if included in prior if-block) if ($no_cache = "1") { add_header Set-Cookie "_mcnc=1; Max-Age=17; Path=/"; add_header X-Microcachable "0"; } # Bypass cache if no-cache cookie is set, these are absolutely critical for Wordpress installations that don't use JS comments if ($http_cookie ~* "(_mcnc|comment_author_|wordpress_(?!test_cookie)|wp-postpass_)") { set $no_cache "1"; } if ($request_uri ~* wpsf-(img|js)\.php) { proxy_ignore_headers Set-Cookie; } # Bypass cache if flag is set proxy_no_cache $no_cache; proxy_cache_bypass $no_cache; # under no circumstances should there ever be a retry of a POST request, or any other request for that matter proxy_next_upstream off; proxy_read_timeout 86400s; # Point nginx to the real app/web server proxy_pass http://localhost; # Set cache zone proxy_cache microcache; # Set cache key to include identifying components proxy_cache_key $scheme$host$request_method$request_uri$mobile_request; # Only cache valid HTTP 200 responses for this long proxy_cache_valid 200 15s; #proxy_cache_min_uses 3; # Serve from cache if currently refreshing proxy_cache_use_stale updating timeout; # Send appropriate headers through proxy_set_header Host $host; # no need for this proxy_set_header X-Real-IP $remote_addr; # no need for this proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for; # Set files larger than 1M to stream rather than cache proxy_max_temp_file_size 1M; access_log /var/log/nginx/androidpolice-microcache.log custom; }

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• Windows: what is the difference between DEP always on and DEP opt-out with no exceptions?

  - by Peter Mortensen

  What is the difference between DEP always on ("/NoExecute=AlwaysOn" in boot.ini) and DEP opt-out ( "/NoExecute=OptOut" in boot.ini) with no exceptions? "no exceptions" = empty list of programs for which DEP does not apply. DEP = Data Execution Prevention (hardware). One would expect it to work the same way, but it makes a difference for some applications. E.g. for all versions of UltraEdit 14 (14.2). It crashes at startup for DEP always on, at least on Microsoft Windows XP Professional Edition x64 edition. (2010-03-11: this problem has been fixed with UltraEdit 15.2 and later.) Update 1: I think this difference is caused by the backdoors that Microsoft has put into hardware DEP for OptOut, according to Fabrice Roux (see below). In the case of IrfanView, for which Steve Gibson observed the same difference as I did for UltraEdit (see below), the difference is caused by a non-DEP aware EXE packer (ASPack) that Microsoft coded a backdoor for. Is there a difference between Windows XP, Windows Vista and Windows 7 ? Is there a difference between 32 bit and 64 bit versions of Windows ? Sources: From [http://blog.fabriceroux.com/index.php/2007/02/26/hardware_dep_has_a_backdoor?blog=1], "Hardware DEP has a backdoor" by Fabrice Roux. 2007-02-26. "IrfanView was not using any trick to evade DEP ... Microsoft just coded a backdoor used only in OPTOUT. Bascially Microsoft checks the executable header for a section matching one of the 3 strings. If one these strings is found, DEP will be turned OFF for this application by windows. ... 'aspack', 'pcle', 'sforce'" From [http://www.grc.com/sn/sn-078.htm], by Steve Gibson. "I can’t find any documentation on Microsoft’s site anywhere, because we’re seeing a difference between always-on and opt-out. That is, you would imagine that always-on mode would be the same as opting out if you weren’t having any opt-out programs. It turns out it’s not the case. For example ... the IrfanView file viewer ... runs fine in opt-out mode, even if it has not been opted out. But it won’t launch, Windows blocks it from launching ... in always-on mode." From [http://www.grc.com/sn/sn-083.htm], by Steve Gibson. "... IrfanView ... won’t run with DEP turned on. It’s because it uses an EXE packer, an executable compression program called ASPack. And it makes sense that it wouldn’t because naturally an executable compressor has got to decompress the executable, so it allocates a bunch of data memory into which it decompresses the compressed executable, and then it runs it. Well, it’s running a data allocation, which is exactly what DEP is designed to stop. On the other hand, UPX, which is actually the leading and most popular EXE compressor, it’s DEP- compatible because those guys realized, hey, when we allocate this memory, we should mark the pages as executable."

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• Varnish + Nginx + multiple IP addresses

  - by adnan

  This is my first shot at making Varnish work on my dedicated server which hosts 2 domains with 2 separate IP-addresses. My simplified setup is as follows: Nginx conf server { listen ip-address-1:8080; } server { listen ip-address-2:8080; } Varnish vcl backend default { .host = "127.0.0.1"; .port = "80"; } And in the varnish conf I have defined VARNISH_LISTEN_PORT=80 Varnish and Nginx (and php-fpm) are running properly but when I try to go to my website it shows the welcome to nginx page. The headers don't have the x-varnish in it. It seems that for some reason varnish is not listening to port 80. I'm suspecting this has to do with the vcl file where it is listening to the 127.0.0.1 host. I'm running two wordpress sites. Where should I look for to get Varnish working properly? Cheers, Adnan EDIT: Nginx seems to be in 8080 correctly but Varnish is not listening to the right ip address. Using Jens multiple varnish ip addresses netstat -lnp yields: Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 46.105.40.241:8080 0.0.0.0:* LISTEN 21610/nginx tcp 0 0 5.135.166.39:8080 0.0.0.0:* LISTEN 21610/nginx tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 21610/nginx tcp 0 0 127.0.0.1:53 0.0.0.0:* LISTEN 2544/named tcp 0 0 0.0.0.0:21 0.0.0.0:* LISTEN 1195/vsftpd tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1184/sshd tcp 0 0 127.0.0.1:953 0.0.0.0:* LISTEN 2544/named tcp 0 0 46.105.40.241:443 0.0.0.0:* LISTEN 21610/nginx tcp 0 0 5.135.166.39:443 0.0.0.0:* LISTEN 21610/nginx tcp 0 0 127.0.0.1:6082 0.0.0.0:* LISTEN 21350/varnishd tcp 0 0 :::80 :::* LISTEN 21351/varnishd tcp 0 0 ::1:53 :::* LISTEN 2544/named tcp 0 0 :::22 :::* LISTEN 1184/sshd tcp 0 0 ::1:953 :::* LISTEN 2544/named udp 0 0 127.0.0.1:53 0.0.0.0:* 2544/named udp 0 0 ::1:53 :::* 2544/named default.vcl backend ikhebeenbril { .host = "5.135.166.39"; .port = "8080"; } backend sunculture { .host = "46.105.40.241"; .port = "8080"; } sub vcl_recv { if (server.ip == "5.135.166.39") { set req.backend = ikhebeenbril; } else { set req.backend = sunculture; } ... } sub vcl_hash { hash_data(server.ip); if (req.http.host) { hash_data(req.http.host); } hash_data(req.url); if (req.http.Accept-Encoding) { hash_data(req.http.Accept-Encoding); } return (hash); } nginx server blocks server { listen 5.135.166.39:80; listen 5.135.166.39:443 default ssl spdy; server_name www.ikhebeenbril.nl; } server { listen 46.105.40.241:80; listen 46.105.40.241:443 default ssl spdy; server_name www.thesunculture.com; }

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• iptables DNS resolution

  - by Favolas

  I have a virtual machine with Fedora 19 acting as a router. This machine as an interface (p8p1) with the IP 172.16.1.254 that is connected to another machine (IP 172.16.1.1) that's simulating the external network. I've installed snort 2.9.2.2, applied the snortsam-2.9.2.2.diff.gz patch and installed snortsam 2.70 on the routermachine In snort.conf besides altering some RULE_PATH I believe I've only added the following line to the file. output alert_fwsam: 127.0.0.1:898/password After doing this two comands: ifconfig p8p1 promisc /usr/local/snort/bin/snort -v -i p8p1 If I ping from the external network to the router IP, I can see the info about the pings. One of the rules that I have is icmp-info.rules that as this single line: alert icmp $EXTERNAL_NET any -> $HOME_NET any (msg:"ICMP-INFO Echo Reply"; icode:0; itype:0; classtype:misc-activity; sid:408; rev:6;fwsam: src, 5 minutes;) snortsam.conf as this data: defaultkey password accept localhost keyinterval 30 minutes dontblock 192.168.1.1 # rede local rollbackhosts 50 rollbackthreshold 20 / 30 secs rollbacksleeptime 1 minute logfile /var/log/snort/snortsam.log loglevel 3 daemon nothreads # linha importante para gerar os bloqueios via iptables iptables p8p1 LOG bindip 127.0.0.1 Now I run this command: /usr/local/snort/bin/snort -u snort -i p8p1 -c /etc/snort/snort.conf -l /var/log/snort -Dq Terminal gives this message: Spawning daemon child... My daemon child 2080 lives... Daemon parent exiting (0) and when I runsnortsam in terminal i got this: SnortSam, v 2.70. Copyright (c) 2001-2009 Frank Knobbe . All rights reserved. Plugin 'fwsam': v 2.5, by Frank Knobbe Plugin 'fwexec': v 2.7, by Frank Knobbe Plugin 'pix': v 2.9, by Frank Knobbe Plugin 'ciscoacl': v 2.12, by Ali Basel <[email protected]> Plugin 'cisconullroute': v 2.5, by Frank Knobbe Plugin 'cisconullroute2': v 2.2, by Wouter de Jong <[email protected]> Plugin 'netscreen': v 2.10, by Frank Knobbe Plugin 'ipchains': v 2.8, by Hector A. Paterno <[email protected]> Plugin 'iptables': v 2.9, by Fabrizio Tivano <[email protected]>, Luis Marichal <[email protected]> Plugin 'ebtables': v 2.4, by Bruno Scatolin <[email protected]> Plugin 'watchguard': v 2.7, by Thomas Maier <[email protected]> Plugin 'email': v 2.12, by Frank Knobbe Plugin 'email-blocks-only': v 2.12, by Frank Knobbe Plugin 'snmpinterfacedown': v 2.3, by Ali BASEL <[email protected]> Plugin 'forward': v 2.8, by Frank Knobbe Parsing config file /etc/snortsam.conf... Linking plugin 'iptables'... Checking for existing state file "/var/db/snortsam.state". Found. Reading state file. Starting to listen for Snort alerts. and snortsam.log as an entry like this 2013/10/25, 10:15:17, -, 1, snortsam, Starting to listen for Snort alerts. Now, from the external machine I do ping 172.16.1.254 and it starts showing the info and an alert file is created in /var/log/snort/ that as the info about the PINGS. Something like: [**] [1:408:6] ICMP-INFO Echo Reply [**] [Classification: Misc activity] [Priority: 3] 10/25-10:35:16.061319 172.16.1.254 -> 172.16.1.1 ICMP TTL:64 TOS:0x0 ID:38720 IpLen:20 DgmLen:84 Type:0 Code:0 ID:1389 Seq:1 ECHO REPLY Also, if I run instead /usr/local/snort/bin/snort snort -v -i p8p1 i got this message: Running in packet dump mode --== Initializing Snort ==-- Initializing Output Plugins! Snort BPF option: snort pcap DAQ configured to passive. The DAQ version does not support reload. Acquiring network traffic from "p8p1". ERROR: Can't set DAQ BPF filter to 'snort' (pcap_daq_set_filter: pcap_compile: syntax error)! Fatal Error, Quitting.. So, this are my questions: Shouldn't snortsam block the PING? Is that DAQ error causing the problem? If so, How can I solve it?

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• Disk operations freeze Debian

  - by Grzenio

  Hi, I have just installed Debian testing on my new desktop and I am not very happy with performance - when I perform a disk intensive operation, e.g. upgrade packages in the system, everything seems to freeze, e.g. changing tabs in Iceweasel takes 3 seconds. I run the Debian on my 3 year old Thinkpad X60 ultra-portable, and I don't have these issues. (every single parameter of the laptop is much worse than the desktop). I am using the default packaged kernel and scripts. I run hdparm -t /dev/sda1 And I got around 96GB/s, which is expected. What else can I try to make it work better? EDIT: grzes:/home/ga# hdparm -i /dev/sda /dev/sda: Model=WDC WD15EARS-00Z5B1, FwRev=80.00A80, SerialNo=WD-WMAVU1362357 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=50 BuffType=unknown, BuffSize=unknown, MaxMultSect=16, MultSect=16 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=2930277168 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 *udma6 AdvancedPM=no WriteCache=enabled Drive conforms to: Unspecified: ATA/ATAPI-1,2,3,4,5,6,7 * signifies the current active mode EDIT2: Even my wife said "on this new computer I can't do anything when I copy the photos from the camera and its much worse than on the old one". So it must be serious. EDIT3: Updated to 2.6.32, but still no improvement EDIT4: I forgot to mention that the new disk is ext4, the old was ext3. EDIT5: Still not solved. I have a P43 ASUS P5QL-E board. Lines from dmesg that seem relevant: [ 0.370850] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 253) [ 0.370852] io scheduler noop registered [ 0.370853] io scheduler anticipatory registered [ 0.370854] io scheduler deadline registered [ 0.370876] io scheduler cfq registered (default) ... [ 0.908233] ata_piix 0000:00:1f.2: version 2.13 [ 0.908243] ata_piix 0000:00:1f.2: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.908246] ata_piix 0000:00:1f.2: MAP [ P0 P2 P1 P3 ] [ 0.908275] ata_piix 0000:00:1f.2: setting latency timer to 64 [ 0.908316] scsi0 : ata_piix [ 0.908374] scsi1 : ata_piix [ 0.909180] ata1: SATA max UDMA/133 cmd 0xa000 ctl 0x9c00 bmdma 0x9480 irq 19 [ 0.909183] ata2: SATA max UDMA/133 cmd 0x9880 ctl 0x9800 bmdma 0x9488 irq 19 [ 0.909199] ata_piix 0000:00:1f.5: PCI INT B -> GSI 19 (level, low) -> IRQ 19 [ 0.909202] ata_piix 0000:00:1f.5: MAP [ P0 -- P1 -- ] [ 0.909228] ata_piix 0000:00:1f.5: setting latency timer to 64 [ 0.909279] scsi2 : ata_piix [ 0.909326] scsi3 : ata_piix [ 0.910021] ata3: SATA max UDMA/133 cmd 0xb000 ctl 0xac00 bmdma 0xa480 irq 19 [ 0.910024] ata4: SATA max UDMA/133 cmd 0xa880 ctl 0xa800 bmdma 0xa488 irq 19 [ 0.915575] FDC 0 is a post-1991 82077 ... [ 1.716062] ata1.00: SATA link up 3.0 Gbps (SStatus 123 SControl 300) [ 1.716074] ata1.01: SATA link down (SStatus 0 SControl 300) [ 1.724318] ata1.00: ATA-8: WDC WD15EARS-00Z5B1, 80.00A80, max UDMA/133 [ 1.724322] ata1.00: 2930277168 sectors, multi 16: LBA48 NCQ (depth 0/32) [ 1.740339] ata1.00: configured for UDMA/133 [ 1.740428] scsi 0:0:0:0: Direct-Access ATA WDC WD15EARS-00Z 80.0 PQ: 0 ANSI: 5 [ 1.746788] scsi 6:0:0:0: CD-ROM ASUS DRW-1608P 1.17 PQ: 0 ANSI: 5 ... [ 1.925981] sd 0:0:0:0: [sda] 2930277168 512-byte logical blocks: (1.50 TB/1.36 TiB) [ 1.926005] sd 0:0:0:0: [sda] Write Protect is off [ 1.926007] sd 0:0:0:0: [sda] Mode Sense: 00 3a 00 00 [ 1.926020] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA [ 1.926092] sda:sr0: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray [ 1.931106] Uniform CD-ROM driver Revision: 3.20 [ 1.931191] sr 6:0:0:0: Attached scsi CD-ROM sr0 ... [ 1.941936] sda1 sda2 sda3 sda4 < sda5 sda6 > [ 1.967691] sd 0:0:0:0: [sda] Attached SCSI disk [ 1.970938] sd 0:0:0:0: Attached scsi generic sg0 type 0 [ 1.970959] sr 6:0:0:0: Attached scsi generic sg1 type 5 ... [ 2.500086] EXT4-fs (sda3): mounted filesystem with ordered data mode ... [ 7.150468] EXT4-fs (sda6): mounted filesystem with ordered data mode

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• dvd drive I/O error?

  - by bobby

  i get dis error evry time i burn a cd/dvd thru my dvd drive...!! Nero Burning ROM bobby 4C85-200E-4005-0004-0000-7660-0800-35X3-0000-407M-MX37-**** (*) Windows XP 6.1 IA32 WinAspi: - NT-SPTI used Nero Version: 7.11.3. Internal Version: 7, 11, 3, (Nero Express) Recorder: Version: UL01 - HA 1 TA 1 - 7.11.3.0 Adapter driver: HA 1 Drive buffer : 2048kB Bus Type : default CD-ROM: Version: 52PP - HA 1 TA 0 - 7.11.3.0 Adapter driver: HA 1 === Scsi-Device-Map === === CDRom-Device-Map === ATAPI-CD ROM-DRIVE-52MAX F: CdRom0 HL-DT-ST DVDRAM GSA-H12N G: CdRom1 ======================= AutoRun : 1 Excluded drive IDs: WriteBufferSize: 83886080 (0) Byte BUFE : 0 Physical memory : 958MB (981560kB) Free physical memory: 309MB (317024kB) Memory in use : 67 % Uncached PFiles: 0x0 Use Inquiry : 1 Global Bus Type: default (0) Check supported media : Disabled (0) 11.6.2010 CD Image 10:43:02 AM #1 Text 0 File SCSIPTICommands.cpp, Line 450 LockMCN - completed sucessfully for IOCTL_STORAGE_MCN_CONTROL 10:43:02 AM #2 Text 0 File Burncd.cpp, Line 3186 HL-DT-ST DVDRAM GSA-H12N Buffer underrun protection activated 10:43:02 AM #3 Text 0 File Burncd.cpp, Line 3500 Turn on Disc-At-Once, using CD-R/RW media 10:43:02 AM #4 Text 0 File DlgWaitCD.cpp, Line 307 Last possible write address on media: 359848 ( 79:59.73) Last address to be written: 318783 ( 70:52.33) 10:43:02 AM #5 Text 0 File DlgWaitCD.cpp, Line 319 Write in overburning mode: NO (enabled: CD) 10:43:02 AM #6 Text 0 File DlgWaitCD.cpp, Line 2988 Recorder: HL-DT-ST DVDRAM G SA-H12N; CDR co de: 00 97 27 18; O SJ entry from: Pla smon Data systems Ltd. ATIP Data: Special Info [hex] 1: D0 00 A0, 2: 61 1B 12 (LI 97:27.18), 3: 4F 3B 4A ( LO 79:59.74) Additional Info [hex] 1: 00 00 00 (invalid), 2: 00 00 00 (invalid), 3: 00 0 0 00 (invalid) 10:43:02 AM #7 Text 0 File DlgWaitCD.cpp, Line 493 Protocol of DlgWaitCD activities: TRM_DATA_MODE1, 2048, config 0, wanted index0 0 blocks, length 318784 blo cks [G: HL-DT-ST DVDRAM GSA-H12N] -------------------------------------------------------------- 10:43:02 AM #9 Text 0 File ThreadedTransferInterface.cpp, Line 986 Prepare [G: HL-DT-ST DVDRAM GSA-H12N] for write in CUE-sheet-DAO DAO infos: ========== MCN: "" TOCType: 0x00; Se ssion Clo sed, disc fixated Tracks 1 to 1: Idx 0 Idx 1 Next T rk 1: TRM_DATA_MODE1, 2048/0x00, FilePos 0 307200 6531768 32, ISRC "" DAO layout: =========== ___Start_|____Track_|_Idx_|_CtrlAdr_|_____Size_|______NWA_|_RecDep__________ -150 | lead-in | 0 | 0x41 | 0 | 0 | 0x00 -150 | 1 | 0 | 0x41 | 0 | 0 | 0x00 0 | 1 | 1 | 0x41 | 318784 | 318784 | 0x00 318784 | lead-out | 1 | 0x41 | 0 | 0 | 0x00 10:43:02 AM #10 Text 0 File SCSIPTICommands.cpp, Line 240 SPTILockVolume - completed successfully for FSCTL_LOCK_VOLUME 10:43:02 AM #11 Text 0 File Burncd.cpp, Line 4286 Caching options: cache CDRom or Network-Yes, small files-Yes ( ON 10:43:03 AM #19 Text 0 File MMC.cpp, Line 18034 CueData, Len=32 41 00 00 14 00 00 00 00 41 01 00 10 00 00 00 00 41 01 01 10 00 00 02 00 41 aa 01 14 00 46 34 22 10:43:03 AM #20 Text 0 File ThreadedTransfer.cpp, Line 268 Pipe memory size 83836800 10:43:16 AM #21 Text 0 File Cdrdrv.cpp, Line 1405 10:43:16.806 - G: HL-DT-ST DVDRAM GSA-H12N : Queue again later 10:43:42 AM #22 SPTI -1502 File SCSIPassThrough.cpp, Line 181 CdRom1: SCSIStatus(x02) WinError(0) NeroError(-1502) Sense Key: 0x04 (KEY_HARDWARE_ERROR) Nero Report 2 Nero Burning ROM Sense Code: 0x08 Sense Qual: 0x03 CDB Data: 0x2A 00 00 00 4D 00 00 00 20 00 00 00 Sense Area: 0x70 00 04 00 00 00 00 10 53 29 A1 80 08 03 Buffer x0c7d9a40: Len x10000 0xDC 87 EB 41 6E AC 61 5A 07 B2 DB 78 B5 D4 D9 24 0x8D BC 51 38 46 56 0F EE 16 15 5C 5B E3 B0 10 16 0x14 B1 C3 6E 30 2B C4 78 15 AB D5 92 09 B7 81 23 10:43:42 AM #23 CDR -1502 File Writer.cpp, Line 306 DMA-driver error, CRC error G: HL-DT-ST DVDRAM GSA-H12N 10:43:55 AM #24 Phase 38 File dlgbrnst.cpp, Line 1767 Burn process failed at 48x (7,200 KB/s) 10:43:55 AM #25 Text 0 File SCSIPTICommands.cpp, Line 287 SPTIDismountVolume - completed successfully for FSCTL_DISMOUNT_VOLUME 10:44:01 AM #26 Text 0 File Cdrdrv.cpp, Line 11412 DriveLocker: UnLockVolume completed 10:44:01 AM #27 Text 0 File SCSIPTICommands.cpp, Line 450 UnLockMCN - completed sucessfully for IOCTL_STORAGE_MCN_CONTROL Existing drivers: Registry Keys: HKLM\Software\Microsoft\Windows NT\CurrentVersion\WinLogon Nero Report 3

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• Where's the Swap File/Partition?

  - by chrisbunney

  I'm investigating the virtual memory configuration of a Debian based Amazon EC2 instance, and as my background isn't in system admin, I'm slightly confused by what I'm seeing. We're using MongoDB, and the monitoring server we have indicates that the Mongo process is using about 20GB of swap space, however I can't figure out where this is located on the server. As far as I can tell from using the various suggested methods from Google, there is either a much smaller amount, or none at all. top indicates that there is 1.8GB of swap memory: top - 15:35:21 up 6 days, 3:23, 1 user, load average: 1.60, 1.43, 1.37 Tasks: 47 total, 2 running, 45 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 1.3%sy, 0.0%ni, 14.7%id, 83.8%wa, 0.0%hi, 0.0%si, 0.1%st Mem: 3928924k total, 2855572k used, 1073352k free, 640564k buffers Swap: 0k total, 0k used, 0k free, 1887788k cached swapon -s doesn't seem to think there's any swap space: Filename Type Size Used Priority free -m doesn't think there's any swap either: total used free shared buffers cached Mem: 3836 3663 172 0 626 2701 -/+ buffers/cache: 336 3500 Swap: 0 0 0 And neither does vmstat: procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 3 0 66224 641372 2874744 0 0 21 5012 21 33 2 2 76 19 But cat /etc/fstab thinks there is a swap partition: /dev/xvda1 / ext3 defaults 1 1 /dev/xvda2 /mnt ext3 defaults 0 0 /dev/xvda3 swap swap defaults 0 0 none /proc proc defaults 0 0 none /sys sysfs defaults 0 0 However df -k gives no indication of the xvda3 partition: Filesystem 1K-blocks Used Available Use% Mounted on /dev/xvda1 16513960 15675324 0 100% / tmpfs 1964460 8 1964452 1% /lib/init/rw udev 1914148 28 1914120 1% /dev tmpfs 1964460 4 1964456 1% /dev/shm So I really don't know what to make of this, because I appear to have a process using about 10 times more virtual memory than what might be available, and I have no idea where this virtual memory is on the system. I'm probably misinterpreting the output of the tools, so I'd be grateful if someone would be able to set me straight: What have I got wrong, what's the right interpretation, and how do you reach that interpretation? EDIT0: We use 10gen's MMS for monitoring the database, the relevant section for memory from the last data point is: "mem": { "virtual": 20749, "bits": 64, "supported": true, "mappedWithJournal": 20376, "mapped": 10188, "resident": 1219 }, This JSON is specific to the database process (I believe) rather than the system as a whole. fdisk -l /dev/xvda outputs... nothing? I tried each of the 3 xvda entries in /etc/fstab as well: root@ip:~# fdisk -l /dev/xvda1 Disk /dev/xvda1: 34.4 GB, 34359738368 bytes 255 heads, 63 sectors/track, 4177 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/xvda1 doesn't contain a valid partition table root@ip:~# fdisk -l /dev/xvda2 root@ip:~# fdisk -l /dev/xvda3 root@ip:~# Edit1: Output of cat /proc/meminfo for the sake of completeness: MemTotal: 3928924 kB MemFree: 726600 kB Buffers: 648368 kB Cached: 2216556 kB SwapCached: 0 kB Active: 1945100 kB Inactive: 994016 kB Active(anon): 60476 kB Inactive(anon): 12952 kB Active(file): 1884624 kB Inactive(file): 981064 kB Unevictable: 0 kB Mlocked: 0 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 387180 kB Writeback: 0 kB AnonPages: 73380 kB Mapped: 1188260 kB Shmem: 48 kB Slab: 149768 kB SReclaimable: 146076 kB SUnreclaim: 3692 kB KernelStack: 1104 kB PageTables: 16096 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 1964460 kB Committed_AS: 305572 kB VmallocTotal: 34359738367 kB VmallocUsed: 16760 kB VmallocChunk: 34359721448 kB HardwareCorrupted: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB DirectMap4k: 3932160 kB DirectMap2M: 0 kB

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• mod evasive not working properly on ubuntu 10.04

  - by Joe Hopfgartner

  I have an ubuntu 10.04 server where I installed mod_evasive using apt-get install libapache2-mod-evasive I already tried several configurations, the result stays the same. The blocking does work, but randomly. I tried with low limis and long blocking periods as well as short limits. The behaviour I expect is that I can request websites until either page or site limit is reached per given interval. After that I expect to be blocked until I did not make another request for as long as the block period. However the behaviour is that I can request sites and after a while I get random 403 blocks, which increase and decrase in percentage, however they are very scattered. This is an output of siege, so you get an idea: HTTP/1.1 200 0.09 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.11 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.09 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.09 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.09 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.10 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.08 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.09 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.10 secs: 75 bytes ==> /robots.txt HTTP/1.1 403 0.09 secs: 242 bytes ==> /robots.txt HTTP/1.1 200 0.09 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.09 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.10 secs: 75 bytes ==> /robots.txt HTTP/1.1 200 0.08 secs: 75 bytes ==> /robots.txt The exac limits in place during this test run were: DOSHashTableSize 3097 DOSPageCount 10 DOSSiteCount 100 DOSPageInterval 10 DOSSiteInterval 10 DOSBlockingPeriod 120 DOSLogDir /var/log/mod_evasive DOSEmailNotify ***@gmail.com DOSWhitelist 127.0.0.1 So I would expect to be blocked at least 120 seconds after being blocked once. Any ideas aobut this? I also tried adding my configuration at different places (vhost, server config, directory context) and with of without ifmodule directive... This doesnt change anything.

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• Windows 7 / Ubuntu Dualboot GRUB Problem.

  - by Tek

  I'd like to first say ahead of time that I'm running a RAID-0 Setup. 1.First of all, I'm glad Ubuntu 9.10 installed flawlessly and detected my RAID-0 setup just fine. The issue I'm having now is that I already had Windows 7 installed and made a small 12GB partition for Linux/Swap. I grabbed EasyBCD 2.0 to edit the W7 bootloader and configured it to use dual boot Grub2 because before it didn't even show the option for Ubuntu. The bootloader points to a file made in the windows directory made by EasyBCD called "C:\NST\AutoNeoGrub0.mbr" which is what I'm guessing grub is booting from. After that I got the option for booting Ubuntu. The problem is that it's sending me to the Grub prompt (probably because it's pointing to \NST|AutoNeoGrub0.mbr?), at first I didn't know what to do but I researched and have to type grub commands to manually boot into Ubuntu Linux. Ex: grubroot (hd0,4) grubkernel /boot/vmlinuz-2.6... root=/dev/disk/by-uuid/24624-2424... grubinitrd boot/initrd.img-2.6... grubboot After all that Ubuntu boots just fine, but how do I fix it permanently? Do I need to edit the bootloader manually (since Easy BCD "autoconfigures")? Some insight on this would rock! Also, it sucks to type the actual uuid since it's REALLY long. I tried getting the name of the drive via fdisk -l but since it's raid 0 I'm guessing I can't do that. How can I get a shorter name of the drive? like /dev/sda, /dev/sdb etc? I've also tried to update to the latest GRUB and I got this: Creating config file /etc/default/grub with new version Generating core.img error: cannot seek /dev/sdc' error: cannot seek/dev/sdc' grub-probe: error: no mapping exists for nvidia_dbedfcca5' Auto-detection of a filesystem module failed. Please specify the module with the option--modules' explicitly. dpkg: error processing grub-pc (--configure): subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of grub2: grub2 depends on grub-pc; however: Package grub-pc is not configured yet. dpkg: error processing grub2 (--configure): dependency problems - leaving unconfigured No apport report written because the error message indicates its a followup error from a previous failure. E: Sub-process /usr/bin/dpkg returned an error code (1) I've also tried: b@dnb:~$ sudo update-grub error: cannot seek /dev/sdc' error: cannot seek/dev/sdc' Generating grub.cfg ... Found linux image: /boot/vmlinuz-2.6.31-14-generic Found initrd image: /boot/initrd.img-2.6.31-14-generic error: cannot seek /dev/sdc' grub-probe: error: no mapping exists fornvidia_dbedfcca5' error: cannot seek /dev/sdc' grub-probe: error: no mapping exists fornvidia_dbedfcca5' Found memtest86+ image: /boot/memtest86+.bin Found Windows 7 (loader) on /dev/mapper/nvidia_dbedfcca1 error: cannot seek /dev/sdc' grub-probe: error: no mapping exists fornvidia_dbedfcca1' done To no avail. Any idea what I can do to fix this mess? :( Edit: This is my disk configuration. b@dnb:~$ sudo df -l Filesystem 1K-blocks Used Available Use% Mounted on /dev/mapper/nvidia_dbedfcca5 12302232 2744788 8932520 24% / udev 1030288 268 1030020 1% /dev none 1030288 964 1029324 1% /dev/shm none 1030288 92 1030196 1% /var/run none 1030288 0 1030288 0% /var/lock none 1030288 0 1030288 0% /lib/init/rw /dev/sr0 706532 706532 0 100% /media/cdrom0 Note: /dev/mapper/nvidia_dbedfcca5 is my Linux boot partition

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• overriding new ubuntu installation

  - by tkoomzaaskz

  I've got a ubuntu 11.10 which has lost its support in May 2013, now I'd like to reintall up to the most up-to-date LTS, which is 12.04. My question is regarding my current partitions and doing backups. Is there a safe way to backup my data on some local partitions instead of copying files into DVDs/external drives (this is very uncormortable in my situation). Following are system commands shoing my disk: $ lsblk NAME MAJ:MIN RM SIZE RO MOUNTPOINT sda 8:0 0 232,9G 0 +-sda1 8:1 0 48,8G 0 +-sda2 8:2 0 63G 0 +-sda3 8:3 0 1K 0 +-sda4 8:4 0 53,7G 0 / +-sda5 8:5 0 18,6G 0 +-sda6 8:6 0 25,5G 0 +-sda7 8:7 0 23,3G 0 [SWAP] sr0 11:0 1 1024M 0 and $ sudo fdisk -l [sudo] password for xyz: Disk /dev/sda: 250.1 GB, 250059350016 bytes glowic: 255, sektorów/sciezke: 63, cylindrów: 30401, w sumie sektorów: 488397168 Jednostka = sektorów, czyli 1 * 512 = 512 bajtów Rozmiar sektora (logiczny/fizyczny) w bajtach: 512 / 512 Rozmiar we/wy (minimalny/optymalny) w bajtach: 512 / 512 Identyfikator dysku: 0xc3ffc3ff Device Boot Beginning End Blocks ID System /dev/sda1 * 2048 102402047 51200000 7 HPFS/NTFS/exFAT /dev/sda2 215044096 347080703 66018304 7 HPFS/NTFS/exFAT /dev/sda3 347082750 488392064 70654657+ 5 Extended /dev/sda4 102402048 215042047 56320000 83 Linux /dev/sda5 395905923 434975939 19535008+ 83 Linux /dev/sda6 434976003 488392064 26708031 83 Linux /dev/sda7 347082752 395905023 24411136 82 Linux swap / Solaris In the beginning I had Windows Vista pre-installed with the machine when it was bought (damn!) and I installed linux (the one I have now). The windows-program in master boot record has been overriden by grub and now I can boot with both Windows and Linux. This is list of mounted devices: $ mount /dev/sda4 on / type ext4 (rw,errors=remount-ro,commit=0) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) fusectl on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev) gvfs-fuse-daemon on /home/tomasz/.gvfs type fuse.gvfs-fuse-daemon (rw,nosuid,nodev,user=tomasz) It's strange (I don't remember such thing) that my current linux uses only one partition (/dev/sda4). But, anyway, it seems like that. My final question is: am I able to use one of the existing linux partitions for a backup and install ubuntu 12.04 without removing neither windows nor ubuntu 11.04? I mean - will grub automatically accept both old windows vista and 2 linuxes (old 11.10 and "new" 12.04)? Is there any hidden operation done while installation that could harm my custom-backup-partition while installing? my fstab file: proc /proc proc nodev,noexec,nosuid 0 0 # / was on /dev/sda4 during installation UUID=d44e89f5-9da2-48eb-83b3-887652ec95d2 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda7 during installation UUID=bbe50535-ba57-434a-9272-211d859f0e00 none swap sw 0 0 sda5 and sda6 are trash partitions created during unsuccessful linux installation (this was linux installation before my current installation), I didn't delete these partitions, but I have access to them (and I can use them as backup partitions). edit: second question is: why does lsblk show /dev/sda having 232,9G while fdisk shows that it has 250.1GB? Where does the difference come from?

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• IP Micro-outages, telephone micro-outages, and CATV micro-outages

  - by Michael Graff

  This is a long and complicated question, mostly because it has been going on for 2.5 years without a solution in sight. It also is only one-third computer related, the other two-thirds are cable TV and cable-phone related. Background I have COX Communications for a cable provider, and we get Internet, digital cable TV, and digital phone service through them. The Internet is a SB5101 right now, and has been a DPC2100 and SB5120 in the past. Same results. The phone service is provided through a telephone interface mounted on the outside of the house (not classic VoIP) and the CATV is through a Scientific Atlanta receiver without DVR. I do have a TiVo connected to the CATV box. Symptoms The CATV shows "blocking" -- sometimes very very short duration where a few blocks appear on the screen. Sometimes it lasts long enough that the video "pauses" for 2-5 seconds, and rarely but not unseen the audio also fails. The CATV decoder box shows no correctable (FEC) or uncorrectable errors. That is, all BER counters are zero for the video stream. The Internet shows "micro-outages" where it appears that sent packets are not making it out, but I continue to receive packets from local modems. That is, pings stop coming back, but I continue to see modems broadcast for DHCP, and sometimes they ask more than once. The cable modem shows no errors during this time, but cable modems lie like you would not believe. It is actually possible to unplug the coax from the modem for 20 seconds and it reports NO ERRORS to the provider's tools. The phone service cuts out for 1-3 seconds, infrequently. When this happens, I hear NOTHING (not even comfort noise) and the remote side hears a "click" as if I were getting a call waiting message. However, there is no call incoming, other than the one I'm currently on of course. Things SEEM to happen more frequently when the temperature outside swings from cold to warm, so fall/spring seems worse than summer/winter. All micro-outages occur between once or twice a day (which I could ignore) to 10 times per hour. All SNR, signal levels, noise levels, etc. show very close to optimal when measured. COX's diagnosis This is a continual pain for me. Over the last 2.5 years, they have opened, "fixed" something, and closed the tickets. They close it without confirming that it is indeed better, and when I reopen they cannot do that, but instead they open a new ticket and send yet another low-level tech out to do the same signal tests and report that all is OK. I've finally gotten a line tech who has a clue and is motivated enough to pursue this with me. We have tried things like switching the local nodes over to UPS and generator power, but this does not trigger the noise. We have tried replacing all cabling, the tap outside my house, the modem, the CATV decoder -- all without resolution. Recently they have decided it is both my computer or switch, my TiVo, and my phone that are all broken and causing this issue. My debugging steps I spent the worse day of my TV-watching life yesterday and part of today. I watched live TV without the TiVo. I witnessed blocking, but it did "feel different." and was actually more severe. Some days it is better, some days it is worse, so perhaps this was just a very bad day. Today, I connected the TiVo to my DVD player, and ran two very long movies through it. I saw no blocking at all during nearly 6 hours of video. Suggestions? Does anyone have any suggestions on what to do next? I understand perhaps only the IP side can be addressed here, but it is one of the more limiting debugging options.

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• XFS disk becomes unavailable after a while

  - by Guard

  Ubuntu 12.04 (but the same was on 11.10 before upgrading) WD MyBook, 2TB, no RAID (or RAID0, not completely sure, anyway no mirroring, both 1TB disks are in use, mounted as a single device). Formatted to XFS, normally used for big movie files. Connected to Firewire 800. At some point the LED started going up and down as when constantly reading/writing. The device gives access error. When unplugged (cable, then holding the power button for a while, then unplugging the power) and re-connected becomes available. xfs_check with no results. xfs_repair did something, but looks like didn't fix any error. Then after a massive read (checking 1.5GB torrent file for integrity) becomes unavailable again. Any ideas what's wrong? Drives? Cables? Motherboard? OS? UPD: not sure how relevant this is, but here are dmesg output [14380.632816] SGI XFS with ACLs, security attributes, realtime, large block/inode numbers, no debug enabled [14380.633356] SGI XFS Quota Management subsystem [14421.812220] firewire_core: phy config: card 0, new root=ffc1, gap_count=5 [14441.890596] firewire_core: phy config: card 0, new root=ffc1, gap_count=5 [14441.896858] firewire_core: phy config: card 0, new root=ffc1, gap_count=5 [14453.895347] firewire_core: created device fw1: GUID 0090a99500a35518, S400, 9 config ROM retries [14453.904818] scsi6 : SBP-2 IEEE-1394 [14453.905014] scsi7 : SBP-2 IEEE-1394 [14454.139993] firewire_sbp2: fw1.0: logged in to LUN 0000 (0 retries) [14454.158769] scsi 6:0:0:0: Direct-Access WD My Book 1015 PQ: 0 ANSI: 4 [14454.159251] sd 6:0:0:0: Attached scsi generic sg3 type 0 [14454.162391] firewire_sbp2: fw1.1: logged in to LUN 0001 (0 retries) [14454.167453] sd 6:0:0:0: [sdc] 3907017568 512-byte logical blocks: (2.00 TB/1.81 TiB) [14454.178822] sd 6:0:0:0: [sdc] Write Protect is off [14454.178826] sd 6:0:0:0: [sdc] Mode Sense: 10 00 00 00 [14454.186830] scsi 7:0:0:1: Enclosure WD My Book Device 1015 PQ: 0 ANSI: 4 [14454.186995] scsi 7:0:0:1: Attached scsi generic sg4 type 13 [14454.190078] sd 6:0:0:0: [sdc] Cache data unavailable [14454.190087] sd 6:0:0:0: [sdc] Assuming drive cache: write through [14454.202176] sd 6:0:0:0: [sdc] Cache data unavailable [14454.202185] sd 6:0:0:0: [sdc] Assuming drive cache: write through [14454.239940] sdc: [mac] sdc1 sdc2 sdc3 sdc4 [14454.271262] sd 6:0:0:0: [sdc] Cache data unavailable [14454.271270] sd 6:0:0:0: [sdc] Assuming drive cache: write through [14454.271354] sd 6:0:0:0: [sdc] Attached SCSI disk [14454.272149] ses 7:0:0:1: Attached Enclosure device [14606.090024] XFS (sdc3): Mounting Filesystem [14612.048343] XFS (sdc3): Starting recovery (logdev: internal) [14620.697636] XFS (sdc3): Ending recovery (logdev: internal) [14748.120957] e1000e: eth0 NIC Link is Up 100 Mbps Full Duplex, Flow Control: Rx/Tx [14748.120963] e1000e 0000:00:19.0: eth0: 10/100 speed: disabling TSO [14752.568382] uhci_hcd 0000:00:1a.0: PCI INT A disabled [14752.568579] uhci_hcd 0000:00:1a.1: PCI INT B disabled [14752.568738] ehci_hcd 0000:00:1a.7: PCI INT C disabled [14752.568779] ehci_hcd 0000:00:1a.7: PME# enabled [14752.584526] uhci_hcd 0000:00:1d.1: PCI INT B disabled [14752.584689] uhci_hcd 0000:00:1d.2: PCI INT C disabled [14752.680079] ehci_hcd 0000:00:1a.7: BAR 0: set to [mem 0xe4641000-0xe46413ff] (PCI address [0xe4641000-0xe46413ff]) [14752.680104] ehci_hcd 0000:00:1a.7: restoring config space at offset 0xf (was 0x300, writing 0x30b) [14752.680136] ehci_hcd 0000:00:1a.7: restoring config space at offset 0x1 (was 0x2900000, writing 0x2900002) [14752.680170] ehci_hcd 0000:00:1a.7: PME# disabled [14752.680182] ehci_hcd 0000:00:1a.7: PCI INT C -> GSI 18 (level, low) -> IRQ 18 [14752.680190] ehci_hcd 0000:00:1a.7: setting latency timer to 64 [14752.710334] uhci_hcd 0000:00:1a.0: PCI INT A -> GSI 16 (level, low) -> IRQ 16 [14752.710342] uhci_hcd 0000:00:1a.0: setting latency timer to 64 [14752.749186] uhci_hcd 0000:00:1a.1: PCI INT B -> GSI 17 (level, low) -> IRQ 17 [14752.749194] uhci_hcd 0000:00:1a.1: setting latency timer to 64 [14752.790231] uhci_hcd 0000:00:1d.1: PCI INT B -> GSI 22 (level, low) -> IRQ 22 [14752.790239] uhci_hcd 0000:00:1d.1: setting latency timer to 64 [14752.829170] uhci_hcd 0000:00:1d.2: PCI INT C -> GSI 18 (level, low) -> IRQ 18 [14752.829178] uhci_hcd 0000:00:1d.2: setting latency timer to 64

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• Causes of sudden massive filesystem damage? ("root inode is not a directory")

  - by poolie

  I have a laptop running Maverick (very happily until yesterday), with a Patriot Torx SSD; LUKS encryption of the whole partition; one lvm physical volume on top of that; then home and root in ext4 logical volumes on top of that. When I tried to boot it yesterday, it complained that it couldn't mount the root filesystem. Running fsck, basically every inode seems to be wrong. Both home and root filesystems show similar problems. Checking a backup superblock doesn't help. e2fsck 1.41.12 (17-May-2010) lithe_root was not cleanly unmounted, check forced. Resize inode not valid. Recreate? no Pass 1: Checking inodes, blocks, and sizes Root inode is not a directory. Clear? no Root inode has dtime set (probably due to old mke2fs). Fix? no Inode 2 is in use, but has dtime set. Fix? no Inode 2 has a extra size (4730) which is invalid Fix? no Inode 2 has compression flag set on filesystem without compression support. Clear? no Inode 2 has INDEX_FL flag set but is not a directory. Clear HTree index? no HTREE directory inode 2 has an invalid root node. Clear HTree index? no Inode 2, i_size is 9581392125871137995, should be 0. Fix? no Inode 2, i_blocks is 40456527802719, should be 0. Fix? no Reserved inode 3 (<The ACL index inode>) has invalid mode. Clear? no Inode 3 has compression flag set on filesystem without compression support. Clear? no Inode 3 has INDEX_FL flag set but is not a directory. Clear HTree index? no .... Running strings across the filesystems, I can see there are what look like filenames and user data there. I do have sufficiently good backups (touch wood) that it's not worth grovelling around to pull back individual files, though I might save an image of the unencrypted disk before I rebuild, just in case. smartctl doesn't show any errors, neither does the kernel log. Running a write-mode badblocks across the swap lv doesn't find problems either. So the disk may be failing, but not in an obvious way. At this point I'm basically, as they say, fscked? Back to reinstalling, perhaps running badblocks over the disk, then restoring from backup? There doesn't even seem to be enough data to file a meaningful bug... I don't recall that this machine crashed last time I used it. At this point I suspect a bug or memory corruption caused it to write garbage across the disks when it was last running, or some kind of subtle failure mode for the SSD. What do you think would have caused this? Is there anything else you'd try?

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• Linux software RAID6: rebuild slow

  - by Ole Tange

  I am trying to find the bottleneck in the rebuilding of a software raid6. ## Pause rebuilding when measuring raw I/O performance # echo 1 > /proc/sys/dev/raid/speed_limit_min # echo 1 > /proc/sys/dev/raid/speed_limit_max ## Drop caches so that does not interfere with measuring # sync ; echo 3 | tee /proc/sys/vm/drop_caches >/dev/null # time parallel -j0 "dd if=/dev/{} bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 7.30336 s, 144 MB/s [... similar for each disk ...] # time parallel -j0 "dd if=/dev/{} skip=15000000 bs=256k count=4000 | cat >/dev/null" ::: sdbd sdbc sdbf sdbm sdbl sdbk sdbe sdbj sdbh sdbg 4000+0 records in 4000+0 records out 1048576000 bytes (1.0 GB) copied, 12.7991 s, 81.9 MB/s [... similar for each disk ...] So we can read sequentially at 140 MB/s in the outer tracks and 82 MB/s in the inner tracks on all the drives simultaneously. Sequential write performance is similar. This would lead me to expect a rebuild speed of 82 MB/s or more. # echo 800000 > /proc/sys/dev/raid/speed_limit_min # echo 800000 > /proc/sys/dev/raid/speed_limit_max # cat /proc/mdstat md2 : active raid6 sdbd[10](S) sdbc[9] sdbf[0] sdbm[8] sdbl[7] sdbk[6] sdbe[11] sdbj[4] sdbi[3](F) sdbh[2] sdbg[1] 27349121408 blocks super 1.2 level 6, 128k chunk, algorithm 2 [9/8] [UUU_UUUUU] [=========>...........] recovery = 47.3% (1849905884/3907017344) finish=855.9min speed=40054K/sec But we only get 40 MB/s. And often this drops to 30 MB/s. # iostat -dkx 1 sdbc 0.00 8023.00 0.00 329.00 0.00 33408.00 203.09 0.70 2.12 1.06 34.80 sdbd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 sdbe 13.00 0.00 8334.00 0.00 33388.00 0.00 8.01 0.65 0.08 0.06 47.20 sdbf 0.00 0.00 8348.00 0.00 33388.00 0.00 8.00 0.58 0.07 0.06 48.00 sdbg 16.00 0.00 8331.00 0.00 33388.00 0.00 8.02 0.71 0.09 0.06 48.80 sdbh 961.00 0.00 8314.00 0.00 37100.00 0.00 8.92 0.93 0.11 0.07 54.80 sdbj 70.00 0.00 8276.00 0.00 33384.00 0.00 8.07 0.78 0.10 0.06 48.40 sdbk 124.00 0.00 8221.00 0.00 33380.00 0.00 8.12 0.88 0.11 0.06 47.20 sdbl 83.00 0.00 8262.00 0.00 33380.00 0.00 8.08 0.96 0.12 0.06 47.60 sdbm 0.00 0.00 8344.00 0.00 33376.00 0.00 8.00 0.56 0.07 0.06 47.60 iostat says the disks are not 100% busy (but only 40-50%). This fits with the hypothesis that the max is around 80 MB/s. Since this is software raid the limiting factor could be CPU. top says: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 38520 root 20 0 0 0 0 R 64 0.0 2947:50 md2_raid6 6117 root 20 0 0 0 0 D 53 0.0 473:25.96 md2_resync So md2_raid6 and md2_resync are clearly busy taking up 64% and 53% of a CPU respectively, but not near 100%. The chunk size (128k) of the RAID was chosen after measuring which chunksize gave the least CPU penalty. If this speed is normal: What is the limiting factor? Can I measure that? If this speed is not normal: How can I find the limiting factor? Can I change that?

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• Setup access to SAS RAID drives with NTFS partitions on CentOS Machine

  - by Quanano

  We have a Dell Poweredge 2900 system with Adaptec 39320A SCSI CONTROLLER CARD and 4 SAS hard drives attached, with NTFS partitions on them. We installed CentOS on the other raid array with a different controller and it is working fine. We are now trying to access the drives shown above and they are not being shown in /dev as sdb, etc. sda is the drive that we installed centos on and it has sda1, sda2, sda3, etc. The CDROM has been picked up as well. If I scan for scsi devices then the perc and adaptec controllers are both found. sg0 is the CDROM and sg2 is the centos installed, however I think sg1 is the other drive but I cannot see anyway to mount the partitions, as only the drive is listed in /dev. Thanks. EXTRA INFO fdisk -l Disk /dev/sda: 72.7 GB, 72746008576 bytes 255 heads, 63 sectors/track, 8844 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x11e3119f Device Boot Start End Blocks Id System /dev/sda1 * 1 64 512000 83 Linux Partition 1 does not end on cylinder boundary. /dev/sda2 64 8845 70528000 8e Linux LVM Disk /dev/mapper/vg_lal2server-lv_root: 34.4 GB, 34431041536 bytes 255 heads, 63 sectors/track, 4186 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_lal2server-lv_root doesn't contain a valid partition table Disk /dev/mapper/vg_lal2server-lv_swap: 21.1 GB, 21139292160 bytes 255 heads, 63 sectors/track, 2570 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_lal2server-lv_swap doesn't contain a valid partition table Disk /dev/mapper/vg_lal2server-lv_home: 16.6 GB, 16647192576 bytes 255 heads, 63 sectors/track, 2023 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Disk /dev/mapper/vg_lal2server-lv_home doesn't contain a valid partition table These are all from the install hdd not the additional hard drives modprobe a320raid FATAL: Module a320raid not found. lsscsi -v [0:0:0:0] cd/dvd TSSTcorp CDRWDVD TS-H492C DE02 /dev/sr0 dir: /sys/bus/scsi/devices/0:0:0:0 [/sys/devices/pci0000:00/0000:00:1f.1/host0/target0:0:0/0:0:0:0] [4:0:10:0] enclosu DP BACKPLANE 1.05 - dir: /sys/bus/scsi/devices/4:0:10:0 [/sys/devices/pci0000:00/0000:00:05.0/0000:01:00.0/0000:02:0e.0/host4/target4:0:10/4:0:10:0] [4:2:0:0] disk DELL PERC 5/i 1.03 /dev/sda dir: /sys/bus/scsi/devices/4:2:0:0 [/sys/devices/pci0000:00/0000:00:05.0/0000:01:00.0/0000:02:0e.0/host4/target4:2:0/4:2:0:0] . lsmod Module Size Used by fuse 66285 0 des_generic 16604 0 ecb 2209 0 md4 3461 0 nls_utf8 1455 0 cifs 278370 0 autofs4 26888 4 ipt_REJECT 2383 0 ip6t_REJECT 4628 2 nf_conntrack_ipv6 8748 2 nf_defrag_ipv6 12182 1 nf_conntrack_ipv6 xt_state 1492 2 nf_conntrack 79453 2 nf_conntrack_ipv6,xt_state ip6table_filter 2889 1 ip6_tables 19458 1 ip6table_filter ipv6 322029 31 ip6t_REJECT,nf_conntrack_ipv6,nf_defrag_ipv6 bnx2 79618 0 ses 6859 0 enclosure 8395 1 ses dcdbas 9219 0 serio_raw 4818 0 sg 30124 0 iTCO_wdt 13662 0 iTCO_vendor_support 3088 1 iTCO_wdt i5000_edac 8867 0 edac_core 46773 3 i5000_edac i5k_amb 5105 0 shpchp 33482 0 ext4 364410 3 mbcache 8144 1 ext4 jbd2 88738 1 ext4 sd_mod 39488 3 crc_t10dif 1541 1 sd_mod sr_mod 16228 0 cdrom 39771 1 sr_mod megaraid_sas 77090 2 aic79xx 129492 0 scsi_transport_spi 26151 1 aic79xx pata_acpi 3701 0 ata_generic 3837 0 ata_piix 22846 0 radeon 1023359 1 ttm 70328 1 radeon drm_kms_helper 33236 1 radeon drm 230675 3 radeon,ttm,drm_kms_helper i2c_algo_bit 5762 1 radeon i2c_core 31276 4 radeon,drm_kms_helper,drm,i2c_algo_bit dm_mirror 14101 0 dm_region_hash 12170 1 dm_mirror dm_log 10122 2 dm_mirror,dm_region_hash dm_mod 81500 11 dm_mirror,dm_log

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• Lustre - issues with simple setup

  - by ethrbunny

  Issue: I'm trying to assess the (possible) use of Lustre for our group. To this end I've been trying to create a simple system to explore the nuances. I can't seem to get past the 'llmount.sh' test with any degree of success. What I've done: Each system (throwaway PCs with 70Gb HD, 2Gb RAM) is formatted with CentOS 6.2. I then update everything and install the Lustre kernel from downloads.whamcloud.com and add on the various (appropriate) lustre and e2fs RPM files. Systems are rebooted and tested with 'llmount.sh' (and then cleared with 'llmountcleanup.sh'). All is well to this point. First I create an MDS/MDT system via: /usr/sbin/mkfs.lustre --mgs --mdt --fsname=lustre --device-size=200000 --param sys.timeout=20 --mountfsoptions=errors=remount-ro,user_xattr,acl --param lov.stripesize=1048576 --param lov.stripecount=0 --param mdt.identity_upcall=/usr/sbin/l_getidentity --backfstype ldiskfs --reformat /tmp/lustre-mdt1 and then mkdir -p /mnt/mds1 mount -t lustre -o loop,user_xattr,acl /tmp/lustre-mdt1 /mnt/mds1 Next I take 3 systems and create a 2Gb loop mount via: /usr/sbin/mkfs.lustre --ost --fsname=lustre --device-size=200000 --param sys.timeout=20 --mgsnode=lustre_MDS0@tcp --backfstype ldiskfs --reformat /tmp/lustre-ost1 mkdir -p /mnt/ost1 mount -t lustre -o loop /tmp/lustre-ost1 /mnt/ost1 The logs on the MDT box show the OSS boxes connecting up. All appears ok. Last I create a client and attach to the MDT box: mkdir -p /mnt/lustre mount -t lustre -o user_xattr,acl,flock luster_MDS0@tcp:/lustre /mnt/lustre Again, the log on the MDT box shows the client connection. Appears to be successful. Here's where the issues (appear to) start. If I do a 'df -h' on the client it hangs after showing the system drives. If I attempt to create files (via 'dd') on the lustre mount the session hangs and the job can't be killed. Rebooting the client is the only solution. If I do a 'lctl dl' from the client it shows that only 2/3 OST boxes are found and 'UP'. [root@lfsclient0 etc]# lctl dl 0 UP mgc MGC10.127.24.42@tcp 282d249f-fcb2-b90f-8c4e-2f1415485410 5 1 UP lov lustre-clilov-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 4 2 UP lmv lustre-clilmv-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 4 3 UP mdc lustre-MDT0000-mdc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 4 UP osc lustre-OST0000-osc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 5 UP osc lustre-OST0003-osc-ffff880037e4d400 00fc176e-3156-0490-44e1-da911be9f9df 5 Doing a 'lfs df' from the client shows: [root@lfsclient0 etc]# lfs df UUID 1K-blocks Used Available Use% Mounted on lustre-MDT0000_UUID 149944 16900 123044 12% /mnt/lustre[MDT:0] OST0000 : inactive device OST0001 : Resource temporarily unavailable OST0002 : Resource temporarily unavailable lustre-OST0003_UUID 187464 24764 152636 14% /mnt/lustre[OST:3] filesystem summary: 187464 24764 152636 14% /mnt/lustre Given that each OSS box has a 2Gb (loop) mount I would expect to see this reflected in available size. There are no errors on the MDS/MDT box to indicate that multiple OSS/OST boxes have been lost. EDIT: each system has all other systems defined in /etc/hosts and entries in iptables to provide access. SO: I'm clearly making several mistakes. Any pointers as to where to start correcting them?

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• How can I recover an ext4 filesystem corrupted after a fsck?

  - by Regan

  I have an ext4 filesystem on luks over software raid5. The filesystem was operating "just fine" for several years when I was beginning to run out of space. I had a 9T volume on 6x2T drives. I began upgrading to 3T drives by doing the mdadm fail, remove, add, rebuild, repeat process until I had a larger array. I then grew the luks container, and then when I unmounted and tried to resize2fs I was given the message the filesystem was dirty and needed e2fsck. Without thinking I just did e2fsck -y /dev/mapper/candybox and it began spewing all kinds of inode being removed type messages (can't remember exactly) I killed e2fsck and tried to remount the filesystem to backup data I was concerned about. When trying to mount at this point I get: # mount /dev/mapper/candybox /candybox mount: wrong fs type, bad option, bad superblock on /dev/mapper/candybox, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so Looking back at my older logs I noticed the filesystem was giving this error each time the machine booted: kernel: [79137.275531] EXT4-fs (dm-2): warning: mounting fs with errors, running e2fsck is recommended So shame on me for not paying attention :( I then tried to mount using every backup superblock (one after another) and each attempt left this in my log: EXT4-fs (dm-2): ext4_check_descriptors: Checksum for group 0 failed (26534!=65440) EXT4-fs (dm-2): ext4_check_descriptors: Checksum for group 1 failed (38021!=36729) EXT4-fs (dm-2): ext4_check_descriptors: Checksum for group 2 failed (18336!=39845) ... EXT4-fs (dm-2): ext4_check_descriptors: Checksum for group 11911 failed (28743!=44098) BUG: soft lockup - CPU#0 stuck for 23s! [mount:2939] Attempts to restart e2fsck results in: # e2fsck /dev/mapper/candybox e2fsck 1.41.14 (22-Dec-2010) e2fsck: Group descriptors look bad... trying backup blocks... candy: recovering journal e2fsck: unable to set superblock flags on candy At this point, I decided it best to order some more drives and make an image using ddrescue Now two weeks later I have an image of the luks partition in a .img file. # ls -lh total 14T -rw-r--r-- 1 root root 14T Oct 25 01:57 candybox.img -rw-r--r-- 1 root root 271 Oct 20 14:32 candybox.logfile After numerous attempts using everything I could find online I could not coerce e2fsck to do anything on the image, so I used mkfs.ext4 -L candy candybox.img -m 0 -S and I was able to mount the dirty filesystem readonly without the journal and recover 960G of data. It gave all kinds of errors of various directories not existing and so forth but I was able to get some stuff. Which gave me some hope! I then ran e2fsck again and it had to recreate the root inode and gave a massive list of correcting group counts, I accepted the root inode creation and said no to everything else, leaving a completely empty filesystem. Re-ran again and said yes to all questions with the same result but now a "clean" but empty filesystem. extundelete gives me 0 recoverable inodes found. And now I'm stuck again, I can't come up with any other methods other than dropping to something like photorec which will give me an absolute mess with how large the filesystem was. I'm willing to re-copy the image from the original array and start over, if I can get any suggestions or ideas on a way to get more of my files back. I wish I could give more detailed logs of the commands that have run, but the output is long scrolled passed except for what gets logged to syslog and my memory is not as detailed due to the timeframe this has occurred over. Any help is greatly appreciated!

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• Is this valid JFS partition?

  - by Coolmax

  This is my first question on StackExchange. My teacher gave my his laptop (with Fedora 16 on it) and compact flash card with data. He want to have access to files on card, but he couldn't get access to it. The problem is Linux don't know what type of partion is. I suppose there is JFS: root@debian:~# dmesg |grep sdc [ 9066.908223] sd 3:0:0:1: [sdc] 3940272 512-byte logical blocks: (2.01 GB/1.87 GiB) [ 9066.962307] sd 3:0:0:1: [sdc] Write Protect is off [ 9066.962310] sd 3:0:0:1: [sdc] Mode Sense: 03 00 00 00 [ 9066.962312] sd 3:0:0:1: [sdc] Assuming drive cache: write through [ 9067.028420] sd 3:0:0:1: [sdc] Assuming drive cache: write through [ 9067.028637] sdc: unknown partition table [ 9067.097065] sd 3:0:0:1: [sdc] Assuming drive cache: write through [ 9067.097281] sd 3:0:0:1: [sdc] Attached SCSI removable disk and some of data: root@debian:~# hexdump -Cn 65536 /dev/sdc 00000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00008000 4a 46 53 31 01 00 00 00 48 63 0e 00 00 00 00 00 |JFS1....Hc......| 00008010 00 10 00 00 0c 00 03 00 00 02 00 00 09 00 00 00 |................| 00008020 00 20 00 00 00 09 20 10 02 00 00 00 00 00 00 00 |. .... .........| 00008030 04 00 00 00 26 00 00 00 02 00 00 00 24 00 00 00 |....&.......$...| 00008040 41 03 00 00 16 00 00 00 00 02 00 00 a0 cc 01 00 |A...............| 00008050 37 00 00 00 69 cc 01 00 b6 d8 ac 4b 00 00 00 00 |7...i......K....| 00008060 32 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 |2...............| 00008070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 00008080 00 00 00 00 00 00 00 00 90 15 e5 5f e3 c4 45 fa |..........._..E.| 00008090 9d 6a 5c b5 4f da 62 1a 00 00 00 00 00 00 00 00 |.j\.O.b.........| 000080a0 00 00 00 00 00 00 00 00 c3 c9 01 00 ed 81 00 00 |................| 000080b0 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 000080c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * [cut] * 0000f000 4a 46 53 31 01 00 00 00 48 63 0e 00 00 00 00 00 |JFS1....Hc......| 0000f010 00 10 00 00 0c 00 03 00 00 02 00 00 09 00 00 00 |................| 0000f020 00 20 00 00 00 09 20 10 00 00 00 00 00 00 00 00 |. .... .........| 0000f030 04 00 00 00 26 00 00 00 02 00 00 00 24 00 00 00 |....&.......$...| 0000f040 41 03 00 00 16 00 00 00 00 02 00 00 a0 cc 01 00 |A...............| 0000f050 37 00 00 00 69 cc 01 00 b6 d8 ac 4b 00 00 00 00 |7...i......K....| 0000f060 32 00 00 00 02 00 00 00 00 00 00 00 00 00 00 00 |2...............| 0000f070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 0000f080 00 00 00 00 00 00 00 00 90 15 e5 5f e3 c4 45 fa |..........._..E.| 0000f090 9d 6a 5c b5 4f da 62 1a 00 00 00 00 00 00 00 00 |.j\.O.b.........| 0000f0a0 00 00 00 00 00 00 00 00 c3 c9 01 00 ed 81 00 00 |................| 0000f0b0 01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| 0000f0c0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................| * 00010000 I'm total newbie to filesystems. I googled and found that JFS superblock may starts on 0x8000 offset. But what next? How to mount this card? If there would be normal partition table I would expect 55 AA on 510th and 511th byte, but first 8000 bytes are clear. Any help would be greatly appreciated. And sorry for my bad english :) Kind regards.

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• Mod_Rewrite w Apache mod_jrun22.so & ColdFusion 9 on cPanel

  - by Eddie B

  How can I utilize mod_rewrite at either the httpd.conf level or per-directory level when mod_jrun22 seems to have short-stopped the rewrite process for ColdFusion pages? I have a ColdFusion 9 based site running on Centos 5.8 w cPanel. cPanel uses EasyApache 3 to manage virtual host containers and as such the conf for mod_jrun22.so, /usr/local/apache/conf/includes/pre_main_global.conf, is loaded prior to the main httpd.conf with the domain specific rules for the container. My assertion is that .cfm pages are failing to be rewritten due to the mod_jk22.so module having priority in the directive chain. To note, I also have a WordPress blog in the site where the rewrites appear to be working fine. For example the following code to remove the index file works fine for php and fails with cfm ... .htaccess under /blog/ : This works Options -Indexes -Multiviews <IfModule mod_rewrite.c> RewriteEngine On RewriteBase /blog/ RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /blog/index.php [L] </IfModule> .htaccess under / : This does not work as expected. Apache serves the page. ASSERT: This would redirect to domain.com/ without index.cfm Options -Indexes -Multiviews <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteRule ^index\.cfm$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.cfm [L] </IfModule> .htaccess under / : This works I'm presuming this is working because the redirect is to another .cfm page and a 404 handler in Application.cfc ... Options -Indexes -Multiviews <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteRule ^.*\.cfm$ - [L] RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{ENV:REDIRECT_STATUS} =404 RewriteRule . /404.cfm$ [L] </IfModule> I've attempted numerous different methods to rewrite .cfm urls ... Adding [PT], [L], [R], [NS], Moving the script to Directory blocks under httpd.conf --- all with the same results ... either the rewrite doesn't work or Apache crashes in an endless loop ... Any help would be greatly appreciated. Below is a single-visit rewrite log snippet for a request to /index.cfm ... the pass-through is taking effect before the rewrite ... cat rewrite_dump_mod | grep index.cfm [perdir /home/foo/public_html/] strip per-dir prefix: /home/foo/public_html/index.cfm -> index.cfm [perdir /home/foo/public_html/] applying pattern '^.*\.cfm$' to uri 'index.cfm' [perdir /home/foo/public_html/] pass through /home/foo/public_html/index.cfm [perdir /home/foo/public_html/] strip per-dir prefix: /home/foo/public_html/index.cfm -> index.cfm [perdir /home/foo/public_html/] applying pattern '^.*\.cfm$' to uri 'index.cfm' [perdir /home/foo/public_html/] pass through /home/foo/public_html/index.cfm * UPDATE * I've managed to figure this out ... it took a while ... Options -Indexes -Multiviews +FollowSymLinks <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteCond %{HTTP_HOST} !^www\. RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L] RewriteCond %{THE_REQUEST} ^.*/index\.cfm RewriteRule ^(.*)index.cfm http://%{HTTP_HOST}/$1 [R=301,L] </IfModule>

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• How to make XAMPP virtual hosts accessible to VM's and other computers on LAN?

  - by martin's

  XAMPP running on Vista 64 Ultimate dev machine (don't think it matters). Machine / Browser configuration Safari, Firefox, Chrome and IE9 on dev machine IE7 and IE8 on separate XP Pro VM's (VMWare on dev machine) IE10 and Chrome on Windows 8 VM (VMware on dev machine) Safari, Firefox and Chrome running on a iMac (same network as dev) Safari, Firefox and Chrome running on a couple of Mac Pro's (same network as dev) IE7, IE8, IE9 running on other PC's on the same network as dev machine Development Configuration Multiple virtual hosts for different projects .local fake TLD for development No firewall restrictions on dev machine for Apache Some sites have .htaccess mapping www to non-www Port 80 is open in the dev machine's firewall Problem XAMPP local home page (http://192.168.1.98/xampp/) can be accessed from everywhere, real or virtual, by IP All .local sites can be accessed from the browsers on the dev machine. All .local sites can be accessed form the browsers in the XP VM's. Some .local sites cannot be accessed from IE10 or Chrome on the W8 VM Sites that cannot be accessed from W8 VM have a minimal .htaccess file No .local sites can be accessed from ANY machine (PC or Mac) on the LAN hosts on dev machine (relevant excerpt) 127.0.0.1 site1.local 127.0.0.1 site2.local 127.0.0.1 site3.local 127.0.0.1 site4.local 127.0.0.1 site5.local 127.0.0.1 site6.local 127.0.0.1 site7.local 127.0.0.1 site8.local 127.0.0.1 site9.local 192.168.1.98 site1.local 192.168.1.98 site2.local 192.168.1.98 site3.local 192.168.1.98 site4.local 192.168.1.98 site5.local 192.168.1.98 site6.local 192.168.1.98 site7.local 192.168.1.98 site8.local 192.168.1.98 site9.local httpd-vhosts.conf on dev machine (relevant excerpt) NameVirtualHost *:80 <VirtualHost *:80> ServerName localhost ServerAlias localhost *.localhost.* DocumentRoot D:/xampp/htdocs </VirtualHost> # ======================================== site1.local <VirtualHost *:80> ServerName site1.local ServerAlias site1.local *.site1.local DocumentRoot D:/xampp-sites/site1/public_html ErrorLog D:/xampp-sites/site1/logs/access.log CustomLog D:/xampp-sites/site1/logs/error.log combined <Directory D:/xampp-sites/site1> Options Indexes FollowSymLinks AllowOverride All Require all granted </Directory> </VirtualHost> NOTE: The above <VirtualHost *:80> block is repeated for each of the nine virtual hosts in the file, no sense in posting it here. hosts on all VM's and physical machines on the network (relevant excerpt) 127.0.0.1 localhost ::1 localhost 192.168.1.98 site1.local 192.168.1.98 site2.local 192.168.1.98 site3.local 192.168.1.98 site4.local 192.168.1.98 site5.local 192.168.1.98 site6.local 192.168.1.98 site7.local 192.168.1.98 site8.local 192.168.1.98 site9.local None of the VM's have any firewall blocks on http traffic. They can reach any site on the real Internet. The same is true of the real machines on the network. The biggest puzzle perhaps is that the W8 VM actually DOES reach some of the virtual hosts. It does NOT reach site2, site6 and site 9, all of which have this minimal .htaccess file. .htaccess file <IfModule mod_rewrite.c> RewriteEngine On RewriteCond %{HTTP_HOST} !^www\. RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L] </IfModule> Adding this file to any of the virtual hosts that do work on the W8 VM will break the site (only for W8 VM, not the XP VM's) and require a cache flush on the W8 VM before it will see the site again after deleting the file. Regardless of whether a .htaccess file exists or not, no machine on the same LAN can access anything other than the XAMPP home page via IP. Even with hosts files on all machines. I can ping any virtual host from any machine on the network and get a response from the correct IP address. I can't see anything in out Netgear router that might prevent one machine from reaching the other. Besides, once the local hosts file resolves to an ip address that's all that goes out onto the local network. I've gone through an extensive number of posts on both SO and as the result of Google searches. I can't say that I have found anything definitive anywhere.

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• What networking hardware do I need in this situation (Fairpoint [ISP] "E-DIA" connection)?

  - by Tegeril

  Right away you'd probably want to say, "Well just ask Fairpoint." I've done that, a number of times in as many different ways I can phrase it and just keep hitting a brick wall where they will not commit to giving any useful information and instead recommend contracting an outside firm and spending a pile of money. Anyway... I'm trying to help a family member out with an office connection that is being setup. I've managed to scrape tiny details here and there from our discussions with the ISP (Fairpoint in Maine) about what is going to be done and what is going to be needed. This is the connection that is being setup: http://www.fairpoint.com/enterprise/vantagepoint/e-dia/index.jsp Information I have been given: Via this connection I can get IPs across different C blocks if that were necessary (it is not) Fairpoint is bringing hardware with them that they claim simply does the conversion from whatever line is coming in the building to ethernet, they have referred to this as the "Fairpoint Netvanta" which I know suggests a line of products that I have looked up, but some (most? all?) of those seems to handle all the routing that I saw. Fairpoint says that I need to bring my own router to sit behind their device. They have literally declined to even suggest products that have worked for other clients in the past and fall back on "any business router works, not a home router." That alone makes my head spin. Detail and clarity hit a brick wall from there. At one moment I got them to cough up that the router I provide needs to be able to do VPN tunneling but they typically fall back to "not a home router" and I was even given "just a business router, Cisco or something, it'll be $500-$1000". Now I know that VPN tunneling routers exist well below that price point and since this connection is going to one machine, possibly two only via ethernet, my desire to purchase networking hardware that over-delivers what I need is not very high. They are literally setting all this up, have provided no configuration details for after they finish, and expect me to just plunk a $500+ router behind it and cross my fingers or contract out to a third party company. If there were other options available for the location, I would have dropped them in a second, but there aren't. The device that is connected requires a static IP and I'm honestly a bit hazy on the necessity of an additional router behind their device and generally a bit over my head. I presume that the router needs to be able to serve external static IPs to its clients, but I really don't know what is going to show up when they come to do the install. This was originally going to be run via an ADSL bridge modem with a range of static IPs (which is easy and is currently setup properly) but the location is too far from the telco to get speeds that we really want for upload and this is also a connection that needs high availability. Any suggestions would be greatly appreciated (I see a number of options in the Cisco Small Business line and other competitors that aren't going to break the bank…), especially if you've worked with Fairpoint before! Thanks for reading my wall of text.

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• Informaton of pendriver with libudv on linux

  - by Catanzaro

  I'm doing a little app in C that read the driver information of my pendrive: Plugged it and typed dmesg: [ 7676.243994] scsi 7:0:0:0: Direct-Access Lexar USB Flash Drive 1100 PQ: 0 ANSI: 0 CCS [ 7676.248359] sd 7:0:0:0: Attached scsi generic sg2 type 0 [ 7676.256733] sd 7:0:0:0: [sdb] 7831552 512-byte logical blocks: (4.00 GB/3.73 GiB) [ 7676.266559] sd 7:0:0:0: [sdb] Write Protect is off [ 7676.266566] sd 7:0:0:0: [sdb] Mode Sense: 43 00 00 00 [ 7676.266569] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.285373] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.285383] sdb: sdb1 [ 7676.298661] sd 7:0:0:0: [sdb] Assuming drive cache: write through [ 7676.298667] sd 7:0:0:0: [sdb] Attached SCSI removable disk with "udevadm info -q all -n /dev/sdb" P: /devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb N: sdb W: 36 S: block/8:16 S: disk/by-id/usb-Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 S: disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 E: UDEV_LOG=3 E: DEVPATH=/devices/pci0000:00/0000:00:11.0/0000:02:03.0/usb1/1-1/1-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb E: MAJOR=8 E: MINOR=16 E: DEVNAME=/dev/sdb E: DEVTYPE=disk E: SUBSYSTEM=block E: ID_VENDOR=Lexar E: ID_VENDOR_ENC=Lexar\x20\x20\x20 E: ID_VENDOR_ID=05dc E: ID_MODEL=USB_Flash_Drive E: ID_MODEL_ENC=USB\x20Flash\x20Drive\x20 E: ID_MODEL_ID=a813 E: ID_REVISION=1100 E: ID_SERIAL=Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 E: ID_SERIAL_SHORT=AA5OCYQII8PSQXBB E: ID_TYPE=disk E: ID_INSTANCE=0:0 E: ID_BUS=usb E: ID_USB_INTERFACES=:080650: E: ID_USB_INTERFACE_NUM=00 E: ID_USB_DRIVER=usb-storage E: ID_PATH=pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 E: ID_PART_TABLE_TYPE=dos E: UDISKS_PRESENTATION_NOPOLICY=0 E: UDISKS_PARTITION_TABLE=1 E: UDISKS_PARTITION_TABLE_SCHEME=mbr E: UDISKS_PARTITION_TABLE_COUNT=1 E: DEVLINKS=/dev/block/8:16 /dev/disk/by-id/usb-Lexar_USB_Flash_Drive_AA5OCYQII8PSQXBB-0:0 /dev/disk/by-path/pci-0000:02:03.0-usb-0:1:1.0-scsi-0:0:0:0 and my software is: Codice: Seleziona tutto #include <stdio.h> #include <libudev.h> #include <stdlib.h> #include <locale.h> #include <unistd.h> int main(void) { struct udev_enumerate *enumerate; struct udev_list_entry *devices, *dev_list_entry; struct udev_device *dev; /* Create the udev object */ struct udev *udev = udev_new(); if (!udev) { printf("Can't create udev\n"); exit(0); } enumerate = udev_enumerate_new(udev); udev_enumerate_add_match_subsystem(enumerate, "scsi_generic"); udev_enumerate_scan_devices(enumerate); devices = udev_enumerate_get_list_entry(enumerate); udev_list_entry_foreach(dev_list_entry, devices) { const char *path; /* Get the filename of the /sys entry for the device and create a udev_device object (dev) representing it */ path = udev_list_entry_get_name(dev_list_entry); dev = udev_device_new_from_syspath(udev, path); /* usb_device_get_devnode() returns the path to the device node itself in /dev. */ printf("Device Node Path: %s\n", udev_device_get_devnode(dev)); /* The device pointed to by dev contains information about the hidraw device. In order to get information about the USB device, get the parent device with the subsystem/devtype pair of "usb"/"usb_device". This will be several levels up the tree, but the function will find it.*/ dev = udev_device_get_parent_with_subsystem_devtype( dev, "block", "disk"); if (!dev) { printf("Errore\n"); exit(1); } /* From here, we can call get_sysattr_value() for each file in the device's /sys entry. The strings passed into these functions (idProduct, idVendor, serial, etc.) correspond directly to the files in the directory which represents the USB device. Note that USB strings are Unicode, UCS2 encoded, but the strings returned from udev_device_get_sysattr_value() are UTF-8 encoded. */ printf(" VID/PID: %s %s\n", udev_device_get_sysattr_value(dev,"idVendor"), udev_device_get_sysattr_value(dev, "idProduct")); printf(" %s\n %s\n", udev_device_get_sysattr_value(dev,"manufacturer"), udev_device_get_sysattr_value(dev,"product")); printf(" serial: %s\n", udev_device_get_sysattr_value(dev, "serial")); udev_device_unref(dev); } /* Free the enumerator object */ udev_enumerate_unref(enumerate); udev_unref(udev); return 0; } the problem is that i obtain in output: Device Node Path: /dev/sg0 Errore and dont view information. subsystem and the devtype i think that are inserted well : "block" and "disk". thanks for help. Bye

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• ASP.NET MVC 3: Implicit and Explicit code nuggets with Razor

  - by ScottGu

  This is another in a series of posts I’m doing that cover some of the new ASP.NET MVC 3 features: New @model keyword in Razor (Oct 19th) Layouts with Razor (Oct 22nd) Server-Side Comments with Razor (Nov 12th) Razor’s @: and <text> syntax (Dec 15th) Implicit and Explicit code nuggets with Razor (today) In today’s post I’m going to discuss how Razor enables you to both implicitly and explicitly define code nuggets within your view templates, and walkthrough some code examples of each of them.  Fluid Coding with Razor ASP.NET MVC 3 ships with a new view-engine option called “Razor” (in addition to the existing .aspx view engine).  You can learn more about Razor, why we are introducing it, and the syntax it supports from my Introducing Razor blog post. Razor minimizes the number of characters and keystrokes required when writing a view template, and enables a fast, fluid coding workflow. Unlike most template syntaxes, you do not need to interrupt your coding to explicitly denote the start and end of server blocks within your HTML. The Razor parser is smart enough to infer this from your code. This enables a compact and expressive syntax which is clean, fast and fun to type. For example, the Razor snippet below can be used to iterate a collection of products and output a <ul> list of product names that link to their corresponding product pages: When run, the above code generates output like below: Notice above how we were able to embed two code nuggets within the content of the foreach loop.  One of them outputs the name of the Product, and the other embeds the ProductID within a hyperlink.  Notice that we didn’t have to explicitly wrap these code-nuggets - Razor was instead smart enough to implicitly identify where the code began and ended in both of these situations.  How Razor Enables Implicit Code Nuggets Razor does not define its own language.  Instead, the code you write within Razor code nuggets is standard C# or VB.  This allows you to re-use your existing language skills, and avoid having to learn a customized language grammar. The Razor parser has smarts built into it so that whenever possible you do not need to explicitly mark the end of C#/VB code nuggets you write.  This makes coding more fluid and productive, and enables a nice, clean, concise template syntax.  Below are a few scenarios that Razor supports where you can avoid having to explicitly mark the beginning/end of a code nugget, and instead have Razor implicitly identify the code nugget scope for you: Property Access Razor allows you to output a variable value, or a sub-property on a variable that is referenced via “dot” notation: You can also use “dot” notation to access sub-properties multiple levels deep: Array/Collection Indexing: Razor allows you to index into collections or arrays: Calling Methods: Razor also allows you to invoke methods: Notice how for all of the scenarios above how we did not have to explicitly end the code nugget.  Razor was able to implicitly identify the end of the code block for us. Razor’s Parsing Algorithm for Code Nuggets The below algorithm captures the core parsing logic we use to support “@” expressions within Razor, and to enable the implicit code nugget scenarios above: Parse an identifier - As soon as we see a character that isn't valid in a C# or VB identifier, we stop and move to step 2 Check for brackets - If we see "(" or "[", go to step 2.1., otherwise, go to step 3  Parse until the matching ")" or "]" (we track nested "()" and "[]" pairs and ignore "()[]" we see in strings or comments) Go back to step 2 Check for a "." - If we see one, go to step 3.1, otherwise, DO NOT ACCEPT THE "." as code, and go to step 4 If the character AFTER the "." is a valid identifier, accept the "." and go back to step 1, otherwise, go to step 4 Done! Differentiating between code and content Step 3.1 is a particularly interesting part of the above algorithm, and enables Razor to differentiate between scenarios where an identifier is being used as part of the code statement, and when it should instead be treated as static content: Notice how in the snippet above we have ? and ! characters at the end of our code nuggets.  These are both legal C# identifiers – but Razor is able to implicitly identify that they should be treated as static string content as opposed to being part of the code expression because there is whitespace after them.  This is pretty cool and saves us keystrokes. Explicit Code Nuggets in Razor Razor is smart enough to implicitly identify a lot of code nugget scenarios.  But there are still times when you want/need to be more explicit in how you scope the code nugget expression.  The @(expression) syntax allows you to do this: You can write any C#/VB code statement you want within the @() syntax.  Razor will treat the wrapping () characters as the explicit scope of the code nugget statement.  Below are a few scenarios where we could use the explicit code nugget feature: Perform Arithmetic Calculation/Modification: You can perform arithmetic calculations within an explicit code nugget: Appending Text to a Code Expression Result: You can use the explicit expression syntax to append static text at the end of a code nugget without having to worry about it being incorrectly parsed as code: Above we have embedded a code nugget within an <img> element’s src attribute.  It allows us to link to images with URLs like “/Images/Beverages.jpg”.  Without the explicit parenthesis, Razor would have looked for a “.jpg” property on the CategoryName (and raised an error).  By being explicit we can clearly denote where the code ends and the text begins. Using Generics and Lambdas Explicit expressions also allow us to use generic types and generic methods within code expressions – and enable us to avoid the <> characters in generics from being ambiguous with tag elements. One More Thing….Intellisense within Attributes We have used code nuggets within HTML attributes in several of the examples above.  One nice feature supported by the Razor code editor within Visual Studio is the ability to still get VB/C# intellisense when doing this. Below is an example of C# code intellisense when using an implicit code nugget within an <a> href=”” attribute: Below is an example of C# code intellisense when using an explicit code nugget embedded in the middle of a <img> src=”” attribute: Notice how we are getting full code intellisense for both scenarios – despite the fact that the code expression is embedded within an HTML attribute (something the existing .aspx code editor doesn’t support).  This makes writing code even easier, and ensures that you can take advantage of intellisense everywhere. Summary Razor enables a clean and concise templating syntax that enables a very fluid coding workflow.  Razor’s ability to implicitly scope code nuggets reduces the amount of typing you need to perform, and leaves you with really clean code. When necessary, you can also explicitly scope code expressions using a @(expression) syntax to provide greater clarity around your intent, as well as to disambiguate code statements from static markup. Hope this helps, Scott P.S. In addition to blogging, I am also now using Twitter for quick updates and to share links. Follow me at: twitter.com/scottgu

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