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  • trying to setup multiple primary partitions on ubuntu linux [migrated]

    - by JohnMerlino
    I currently have ubuntu desktop installed on a harddrive. I want to partition the harddrive so that I can reserve 30 gigs for ubuntu server and 30 gigs for ubuntu desktop. The drive has 300 gigs available. Right now I am booting from dvd drive and installing ubuntu server. I selected "Guided partitioning" and created a 30 gig primary partition of Ext4 journaling filesystem, set "yes, format it" for format partition and set bootable flag to on. I intend to use this 30 gig partition to hold ubuntu server and allow me to boot from it. Now I have two other partitions. They are both set to "logical", one is currently using 285.8 gigs and is using ext4 (when I try to set bootable flag to true, it gives a warning "You are trying to set the bootable flag on a logical partition. The bootable flag is only useful on the primary partitions"). More alarming it says "No existing file system was detected in this partition". Actually, Im thinking that this is the parittion that is supposed to be holding my current Ubuntu Desktop. And of course I want this to be bootable and be a primary partition, so I could dual boot from this and the server partition. Now the third partition is also set to logical and it is being used as swap area. My question is regarding that second partition. Its supposed to be a primary partition thats holding my existing ubuntu desktop edition. How do I switch it to primary and to make sure that its pointing to my existing desktop installation?

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  • Scaling a node.js application, nginx as a base server, but varnish or redis for caching?

    - by AntelopeSalad
    I'm not close to being well versed in using nginx or varnish but this is my setup at the moment. I have a node.js server running which is serving either json, html templates, or socket.io events. Then I have nginx running in front of node which is serving all static content (css, js, etc.). At this point I would like to cache both static content and dynamic content to memory. It's to my understanding that varnish can cache static content quite well and it wouldn't require touching my application code. I also think it's capable of caching dynamic content too but there cannot be any cookie headers? I do use redis at the moment for holding session data and planned to use it for other things in the future like keeping track of non-crucial but fun stats. I just have no idea how I should handle caching everything on the site. I think it comes down to these options but there might be more: Throw varnish in front of nginx and let varnish cache static pages, no app code changes. Redis would cache dynamic db calls which would require modifying my app code. Ignore using varnish completely and let redis handle caching everything, then use one of the nginx-redis modules. I'm not sure if this would require a lot of app code changes (for the static files). I'm not having any luck finding benchmarks that compare nginx+varnish vs nginx+redis and I'm too inexperienced to bench it myself (high chances of my configs being awful). I'm basically looking for the solution that would be the most efficient in terms of req/sec and scalable in the future (throw new hardware at the problem + maybe adjust some values in a config = new servers up and running semi-painlessly).

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  • Advice on cloning disk

    - by hks
    I'm going to buy a second disk for backup, the same size as my laptops. I want to mount it in a casing via usb and backup an entire hdd every soemtime. That's because I want the posibility to just switch drives in case of something goes wrong. I'm using Linux and obviously the right tool seems to be dd. The thing is that my laptop drive has a speed of around 50-70 MB/s and usb 2.0 is 57 MB/s. So to copy my 250GB disk should take me more than 1 hour if I'm lucky. I can't wait this much. I want some differential backup. I read one of JWZ articles. In it he gives more details for using rsync on Mac. He writes that there is possibility of making rsync'ed disk bootable. So my question is: how to make rsync'ed hdd bootable under Linux or are there other 'quick backup' tools for Linux that would allow me to just swap drives? Or should I just stick to dd :( ?

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  • Oracle Linux screen freezes during installation

    - by Fearless
    I was installing Oracle Linux 6.4 on a server, and the screen suddenly froze. Here were the previous steps: I put in the disk, clicked install, checked the disk (no errors), did pre-install setup (clock, root password, host+domain name, etc.), configured two 40GB hard drives in a RAID1 array (no swap, 3100mb encrypted raid partitions, ~100mb ext4 partition mounting to /boot, encrypted ext4 RAID device with mounting to /), selected packages, hit continue. The system did its short preinstall processes, then when to the main installation screen with the long status bar. The installer proceeded like always, but around package 250 out of ~1000, the screen suddenly went black with a text cursor in the upper left corner of the screen and the mouse cursor in its previous place. Neither cursor moved and the only thing that triggered a response was a ctrl-alt-delete that rebooted it. I have run this in VMs before without this issue. Memtest hasn't reported anything, and the media check went smoothly. The machine has supported Ubuntu server without issues before. Any ideas? I have tried booting after that, but the grub bootloader tries to find fd0 for some reason (I have no idea why it would search for the floppy disk). UPDATE My server successfully installed, but won't boot up. I think that, for some reason, it is still using the old bootloader from the previous installation. Any ideas on how to fix that?

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  • memory usage setting

    - by user127610
    everybody,the memory usage is too much,what can i do? top - 12:54:37 up 7 days, 4:38, 1 user, load average: 0.00, 0.00, 0.00 Tasks: 18 total, 2 running, 16 sleeping, 0 stopped, 0 zombie Cpu(s): 0.0%us, 0.0%sy, 0.0%ni,100.0%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1048800k total, 917424k used, 131376k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 15 0 2840 1364 1204 S 0.0 0.1 0:02.17 init 1161 root 14 -4 2320 600 420 S 0.0 0.1 0:00.00 udevd 1391 root 18 0 35512 1288 948 S 0.0 0.1 0:03.53 rsyslogd 1409 root 15 0 8432 1164 700 S 0.0 0.1 0:03.87 sshd 1416 root 18 0 3156 868 692 S 0.0 0.1 0:00.00 xinetd 1423 root 18 0 8672 716 292 S 0.0 0.1 0:00.00 saslauthd 1424 root 18 0 8672 488 64 S 0.0 0.0 0:00.00 saslauthd 1431 root 15 0 7020 1168 616 S 0.0 0.1 0:00.99 crond 1450 root 25 0 6236 1444 1228 S 0.0 0.1 0:00.05 sh 3328 mysql 15 0 799m 42m 4892 S 0.0 4.1 0:02.07 mysqld 15479 root 15 0 11304 3332 2688 R 0.0 0.3 0:00.06 sshd 15482 root 15 0 6372 1688 1404 S 0.0 0.2 0:00.00 bash 15497 root 15 0 2536 1044 864 R 0.0 0.1 0:00.00 top 20137 www 15 0 20672 14m 864 S 0.0 1.4 0:00.87 nginx 22351 www 16 0 52324 26m 9244 S 0.0 2.6 0:13.94 php-fpm 24231 www 16 0 51928 25m 9260 S 0.0 2.5 0:13.52 php-fpm 32682 root 15 0 35832 3228 864 S 0.0 0.3 0:02.18 php-fpm 32686 root 18 0 7368 1616 888 S 0.0 0.2 0:00.00 nginx

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  • Read access to Active Directory property (uSNChanged)

    - by Tom Ligda
    I have an issue with read access to the uSNChanged property when doing LDAP searches. If I do an LDAP search with a user that is a member of the Domain Admins group (UserA), I can see the uSNChanged property for every user. The problem is that if I do an LDAP search with a user (UserB) that is not a member of the Domain Admins group, I can see the uSNChanged property for some users (UserGroupA) and not for some users (UserGroupB). When I look at the users in UserGroupA and compare them to the users in UserGroupB, I see a crucial difference in the "Security" tab. The users in UserGroupA have the "Include inheritable permissions from this object's parent" unchecked. The users in UserGroupB have that option checked. I also noticed that the users in UserGroupA are users that were created earlier. The users in UserGroupB are users created recently. It's difficult to quantify, but I estimate the border between creation time between the users in UserGroupA and UserGroupB is about 6 months ago. What can cause the user creation to default to having that security property checked as opposed to unchecked? A while back (maybe around 6 months ago?) I changed the domain functional level from Windows Server 2003 to Windows Server 2008 R2. Would that have had this effect? (I can't exactly downgrade the domain functional level to test it out.) Is this security property actually the cause of the issue with read access to the uSNChanged property on LDAP searches? It seems correlated, but I'm not sure about causation. What I want in the end is for all authenticated users to have read access to the uSNChanged property for all users when doing an LDAP search. I would also be OK if I could grant read access for that property to an AD group. Then I can control access by adding members to the group.

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  • Calculating memory footprints using /proc/sysvipc/shm

    - by MarkTeehan
    This is for a SLES 10 database server. One of my servers runs three databases and three app servers; I am analyzing how their shared memory segments grow and shrink to avoid intermittent out-of-memory scenarios. "Top" is hot helpful for this since its calculations for RES and VIRT are inconsistent. I am doing this by matching up the contents of /proc/sysvipc/shm with memory usage reported by the database admin console. I do this by totaling up saving the contents of /proc/sysvipc/shm and then total up "bytes" for all of the segments for the offending userid. This is a large server with hundreds of segments and tens (or hundreds) of GB of allocated memory per userid. However it doesn't match up - the database management software claims to be using around 25% more memory than the total I calculate. Negligible swap space is in use, so I am ignoring that. I am running it as root so I am sure I see all shared memory segments. My question is : is all (significant) allocated memory recorded in /proc/sysvipc/shm, or is this only shared memory (*and not "un-shared" memory?). If this is incorrect, what is the correct way to calculate out the total allocated memory for each userid? Also: I believe doing a 'cat' on this file locks server IPC. I check it every 5 seconds - is it likely that this frequency could be problematic? Thanks! Mark Teehan Singapore

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  • Find out what fonts are being sent to a printer

    - by user38307
    I have an issue where two computers running XP and with identical print drivers have different behavior printing over parallel port to receipt printers. For one type of receipt, receipt printing is instant. For another kind printing is delayed by ten seconds on most machines but not on the other. This happens even if I swap out printers. I believe the delay is because this computer has a different set of fonts installed. (It is used for graphic design.) The printers have built-in fonts, and if you do not use one of the built-in fonts the printer has to build up an image in memory rather than just spitting out its fonts. For a particular kind of receipt with special fonts on a particular computer the computer is sending a font which the receipt printer does not have built in. My question is, is there a way to find out what fonts are being sent to the printer? This would let me narrow down what I need to modify in the Windows font folder. Thank you!

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  • How to make a redundant desktop system with daily snapshots? (Is btrfs ready for use?)

    - by TestUser16418
    I want to configure a desktop system in which the home filesystem would be redundant (e.g. RAID-1), and would have weekly snapshots taken. I've already done this with ZFS, the snapshot system is wonderful, and with send/recv you can easily create backups on external media. Unfortunately, at that point, I want GNU+Linux and not FreeBSD or Solaris, so I'm looking for suggestions for good alternatives. I reckon that my alternatives are: btrfs - it seems to be exactly what I need, it has snapshots and commands that allow you to easily replicate zfs send. Yet all documentation mentions that it's still experimental. I can't seem to find any actual reports on its reliability or usability issues. Can you point me to any information on that issue that could clarify whether it would be a possible choice? I have a large preference for this option, mostly because I don't want to reformat the drives when btrfs becomes ready, but I there's no information on whether it's usable at all, whether it's a silly idea to use it, etc. The question that I cannot get the answer to is what does "experimental" mean. lvm snapshots and ext4 - preferably not, since it can consume an awful amount of space when new files are created. Creating 200 GB files requres 200 GB free space and 200 GB additionally for snapshots. I also have found it unreliable -- failed metadata rewrite results in an unreadable PV. I'm wondering how btrfs would compare here. A single filesystem (ext4) on a RAID-1 array with custom COW snapshots with hardlinks (like cp -al). That's my current preference if I can't use btrfs. So how experimental btrfs is, which should I choose, and do I have any other options? What if I don't keep external incremental backups, would that affect my choice?

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  • Grub Installation Failed: Fatal Error ... now what I do?

    - by eklavya
    I know there are some threads that touch this but I feel I have done something uniquely stupid. hence the post and plea for help. I am a beginner @ Linux. So I have a PC with a HDD (hard disk drive) and SSD (solid state drive) It was running Linux Mint /dev/sda1 - HDD Partition 1 - 2 TB (mounted this is /home /dev/sda2 - HDD Partition 2 - 1 TB (separate back up drive, i was backing up files to this) /dev/sdb1 - SSD Partition 1 - 100 GB (OS) /dev/sdb2 - SSD Partition 2 - 20 GB (Swap) The operating system was Linux Mint and was installed on the /dev/sdb1 i.e the solid state drive. I had partitioned off the sda into 2 TB and 1TB and presented the 2 TB as the /home to the OS. Anyway last night I decided to make a return to Ubuntu via the path of Elementary OS. Everything went fine with the install until it stated that GRUB installed failed and this was a Fatal error (no kidding I said). No I am stuck. I have definitely done something wrong and don't know what it is... My biggest pain is the files on the /dev/sda2. I want to save these before I try something drastic like wiping off the /dev/sda completely. So I have the following questions... Can I use a liveCD USB to save these files ? I can see the /dev/sda2 but was unable to access the files in the liveCD last not least ... how do I fix the main issue here. Why could the OS not install GRUB 2b... why is my SSD the /dev/sdb ... and not /dev/sda. Does that have something to do with it that my master boot record sits on the HDD /dev/sda and not /dev/sdb

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  • linux kernel buffer memory is zero

    - by user64772
    Hi all. There are one qestion that i can`t find in google. I have many linux boxes mostly with SLES or openSUSE, diffrent versions and kernels. On some of them i faced with slow oracle transactions problem. It time to time problem and when i log in the box on that time i see that oracle blocked in kernel function sync_page # while :; do ps axo stat,pid,cmd,wchan | egrep '^D|^R'; echo --; sleep 5; done D 3483 hald-addon-storage: polling ide_do_drive_cmd Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page D 12457 [smtpd] sync_page R+ 12458 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12501 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12535 ps axo stat,pid,cmd,wchan - -- Ds 4635 ora_dbw0_orcl sync_page Ds 4637 ora_lgwr_orcl sync_page Ds 4639 ora_ckpt_orcl sync_page D 11210 oracleorcl (LOCAL=NO) sync_page R+ 12570 ps axo stat,pid,cmd,wchan - -- so i think that box is run out of memory for disk buffers but memry is fine total used free shared buffers cached Mem: 4149084 3994552 154532 0 0 2424328 -/+ buffers/cache: 1570224 2578860 Swap: 3148700 750696 2398004 i think that this is the problem, buffer is zero and we must write directly to disk, but why buffer is zero ? - i try to google it and find nothing - is anyone can help ?

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  • How to verify that a physical volume is encrypted? (Ubuntu 10.04 w/ LUKS)

    - by Bob B.
    I am very new to LUKS. During installation, I tried to set up an encrypted physical volume so that everything underneath it would be encrypted. I chose "Use as: physical volume for encryption," the installation completed and I have a working environment. How can I verify that the PV is indeed encrypted? I was never prompted to provide a passphrase, so I most likely missed a step somewhere. At the end of the day, I'd like whole disk encryption if that's possible, so I don't have to worry about which parts of the file system are encrypted and which aren't. If I did miss something, do I have to start over and try again, or can it be done (relatively easily?) after the fact? I would prefer not to introduce more complexity by using TrueCrypt, etc. Environment details: The drives are md raid1. One volume group. A standard boot lv. An encrypted swap lv using a random key (which seems to be working fine). Thank you in advance for your help. This is very much a learn-as-I-go experience.

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  • Amazon EC2 - Free memory

    - by Damo
    We have an amazon ec2 small instance running and over the past few days we noticed that the memory is going down and down. On the small instance, we are running apache and tomcat6 Tomcat is started with the following JVM parameters -Xms32m -Xmx128m -XX:PermSize=128m -XX:MaxPermSize=256m We use nagios to monitor stuff like updates to apply, free disk space and memory. Everything else is behaving as expected but our memory is going down all the time. Our app receives approx half a million hits a day When I shutdown apache and tomcat, and ran free -m, we had only 594mb of memory free out out of the 1.7gb of memory. Not much else is running on the small instance and when running the top command I cannot see where the memory is going. The app we run on tomcat is a grails webapp. Could there be a possibility that there is a memory leak within our application? I read online and folks say that a small amazon instance is perfect for running apach and tomcat. I found a few posts online that showed how to setup apache and tomcat to limit the memory usage and I have already performed those steps. The memory is not being used up as quick but the memory is still decreasing over time. We have other amazone ec2 small instances running grails apps and the memory is fairly standard on those nodes. But they would not be receiving as much traffic Just to add, when I run the top command on the problem server, I cannot see where all the memory is being used Any help with this is greatly appreciated The output of free -m when run on my server is as follows total used free shared buffers cached Mem: 1657 1380 277 0 158 773 -/+ buffers/cache: 447 1209 Swap: 895 0 895 In your opinion, does this look ok? At what stage would the OS give back memory, would it wait to the memory reaches 0% or is this OS dependent?

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  • Windows 7: moved system partition, need to update boot partition

    - by Actorclavilis
    So, I have a decently standard Windows7/Ubuntu dual-boot setup, and (since Ubuntu is my usual operating system) I found I needed to grow my Ubuntu partition and shrink my W7 partition. Originally, my system (500G) looked like this: W7 Boot Partition (1.5G) Ubuntu (around 240G) W7 (same as Ubuntu) (on an extended partition, all by itself) Swap (rest of disk, around 16G) Now I'm no stranger to partitioning and filesystem tools, especially GParted, which I used on a Linux boot disk. After my partition editing, the partitions are laid out the same, except the Ubuntu partition is now 407G and the W7 partition is smaller to compensate. I had supposed, based on http://www.gparted.org/faq.php, that I would be able to run the W7 install disk in recovery mode and have it deal with the rearrangement, then possibly reinstall GRUB or something. Well, now the W7 install disk doesn't even see my W7 installation. All my files are there, the NTFS is perfectly clean, no problems there, but the install disk won't notice it. (Of course, the GRUB entry works fine but the W7 boot partition (which I didn't change) refuses to boot it.) So, basically, any ideas on how to fix this? I don't especially want to rerun the entire install procedure because I'll have a bunch of programs to reinstall (never mind redoing GRUB), but I fear that might be the only option. Thanks.

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  • How to chain GRUB2 for Ubuntu 10.04 from Truecrypt & its bootloader (multi boot alongside Windows XP partition)?

    - by Rob
    I want Truecrypt to ask for password for Windows XP as usual but with the standard [ESC] option, on selecting that, i.e via Escape key, I want it to find the grub for the (unencrypted) Ubuntu install. I've installed Windows XP on the 120Gb hard drive of a Toshiba NB100 netbook then partitioned to make room for Ubuntu 10.04 and installed that after the Windows XP install. When I encrypt Windows XP, Truecrypt will overwrite the grub entry in the master boot record (MBR), I believe (?) and I won't be able to choose between XP and Ubuntu anymore. So I need to restore it back. I've searched fairly extensively for answers on Ubuntu forums and elsewhere but have not yet found a complete answer that covers all eventualities, scenarios and error messages, or otherwise they talk of legacy GRUB and not GRUB2. Ubuntu 10.04 uses GRUB2. My setup: Partitions: Windows XP, NTFS (to be encrypted with Truecrypt), 40Gb /boot (Ext4, 1Gb) Ubuntu swap, 4Gb Ubuntu / (root) - main filesystem (20gb) NTFS share, 55Gb I know that the Truecrypt boot loader replaces the GRUB when boot up because I've already tried it on another laptop. I want boot loader screen to look something like the usual: Truecrypt Enter password: (or [ESC] to skip) password is for WindowsXP and on pressing [ESC] for it to find the Ubuntu grub to boot from Thanks in advance for your help. The key area of the problem is how to instruct Truecrypt when escape key is pressed, and how the Grub/Ubuntu can be made visible to the truecrypt bootloader to find it, when the esc key is pressed. Also knowing as chaining.

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  • Data recovery on working hard drive

    - by emgee
    So I have a 5 bay hot swap SATA enclosure that's connected to a Silicon Image-based SATA adapter in a computer. It's running XP Pro. There are two 1.5TB hard drives in slots 1 and 2 respectively, set up using RAID 1 using the the Silicon Image utility. There are also two 1TB drives in bays 3 and 4, also set to RAID 1 the same way. The partitions for both RAID arrays are Dynamic partitions. A few days back, there was a bare hard drive that needed some files copied off of, so it was popped it in bay 5, that bay to pass-through, and the copied data off of it. Later, I noticed that my 1.5TB drives no longer showed up in windows. In the Silicon Image utility, the drives showed up fine, no error. However, in Device Manager, it shows the RAID 1 array as uninitialized. It shows up as the right size, etc., but nothing else. There's no sign of anything wrong with either drive, so I'm not sure what happened exactly. I'm not the only one who has access to that computer, so it is possible there is something else done to it that I don't know of. There's quite a lot of data on it still, and if at all possible, I'd prefer to not send it to Ontrack. Does anyone know of software that would restore the partitions, keeping in mind that it's a Windows LDM partition? I have access to a variety of Operating Systems, so something that would work on Mac, Windows or Linux would be acceptable. The programs I usually use are not compatible with LDM.

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  • What Logs / Process Stats to monitor on a Ubuntu FTP server?

    - by Adam Salkin
    I am administering a server with Ubuntu Server which is running pureFTP. So far all is well, but I would like to know what I should be monitoring so that I can spot any potential stability and security issues. I'm not looking for sophisticated software, more an idea of what logs and process statistics are most useful for checking on the health of the system. I'm thinking that I can look at various parameters output from the "ps" command and compare to see if I have things like memory leaks. But I would like to know what experienced admins do. Also, how do I do a disk check so that when I reboot, I don't get a message saying something like "disk not checked for x days, forcing check" which delays the reboot? I assume there is command that I can run as a cron job late at night. How often should it be run? What things should I be looking at to spot intrusion attempts? The only shell access is SSH on a non-standard port through UFW firewall, and I regularly do a grep on auth.log for "Fail" or "Invalid". Is there anything else I should look at? I was logging the firewall (UFW) but I have very few open ports (FTP and SSH on a non standard port) so looking at lists of IP's that have been blocked did not seem useful. Many thanks

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  • rsync --remove-source-files but only those that match a pattern

    - by user28146
    Is this possible with rsync? Transfer everything from src:path/to/dir to dest:/path/to/other/dir and delete some of the source files in src:path/to/dir that match a pattern (or size limit) but keep all other files. I couldn't find a way to limit --remove-source-files with a regexp or size limit. Update1 (clarification): I'd like all files in src:path/to/dir to be copied to dest:/path/to/other/dir. Once this is done, I'd like to have some files (those that match a regexp or size limit) in src:path/to/dir deleted but don't want to have anything deleted in dest:/path/to/other/dir. Update2 (more clarification): Unfortunately, I can't simply rsync everything and then manually delete the files matching my regexp from src:. The files to be deleted are continuously created. So let's say there are N files of the type I'd like to delete after the transfer in src: when rsync starts. By the time rsync finishes there will be N+M such files there. If I now delete them manually, I'll lose the M files that were created while rsync was running. Hence I'd like to have a solution that guarantees that the only files deleted from src: are those known to be successfully copied over to dest:. I could fetch a file list from dest: after the rsync is complete, and compare that list of files with what I have in src:, and then do the removal manually. But I was wondering if rsync can do this by itself.

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  • Howto detect fake RAM

    - by Michael
    I just bought a virtual server which should have 2GB of RAM. Now i got a server with 4gb which looks very strange to me. I think it is just a virtual RAM. dmidecode only ouputs /dev/mem: Operation not permitted How can i check if it's a real RAM or just a virtual one? free -m outputs: total used free shared buffers cached Mem: 4093 364 3728 0 0 346 -/+ buffers/cache: 18 4074 Swap: 0 0 0 Output from cat /proc/user_beancounters Version: 2.5 uid resource held maxheld barrier limit failcnt 137: kmemsize 8922287 10194944 2145910784 2145910784 0 lockedpages 0 0 523904 523904 0 privvmpages 13387 59112 9223372036854775807 9223372036854775807 0 shmpages 769 785 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numproc 22 54 9223372036854775807 9223372036854775807 0 physpages 93377 106010 0 1047808 0 vmguarpages 0 0 9223372036854775807 9223372036854775807 0 oomguarpages 2471 2473 9223372036854775807 9223372036854775807 0 numtcpsock 5 21 9223372036854775807 9223372036854775807 0 numflock 4 13 9223372036854775807 9223372036854775807 0 numpty 1 1 9223372036854775807 9223372036854775807 0 numsiginfo 0 39 9223372036854775807 9223372036854775807 0 tcpsndbuf 102592 381632 9223372036854775807 9223372036854775807 0 tcprcvbuf 81920 4820184 9223372036854775807 9223372036854775807 0 othersockbuf 4624 61632 9223372036854775807 9223372036854775807 0 dgramrcvbuf 0 9248 9223372036854775807 9223372036854775807 0 numothersock 39 56 9223372036854775807 9223372036854775807 0 dcachesize 4178917 4232732 1072955392 1072955392 0 numfile 378 535 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 dummy 0 0 9223372036854775807 9223372036854775807 0 numiptent 24 24 9223372036854775807 9223372036854775807 0

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  • Is it safe to format this partition?

    - by xanesis4
    On a ubuntu server I own, I am running out of space. When I ran sudo parted /dev/sda -l to find all available drives, I got this: Model: ATA ST31000528AS (scsi) Disk /dev/sda: 1000GB Sector size (logical/physical): 512B/512B Partition Table: msdos Number Start End Size Type File system Flags 1 1049kB 256MB 255MB primary ext2 boot 2 257MB 1000GB 1000GB extended 5 257MB 1000GB 1000GB logical lvm Model: Linux device-mapper (linear) (dm) Disk /dev/mapper/server--vg-swap_1: 2135MB Sector size (logical/physical): 512B/512B Partition Table: loop Number Start End Size File system Flags 1 0.00B 2135MB 2135MB linux-swap(v1) Model: Linux device-mapper (linear) (dm) Disk /dev/mapper/server--vg-root: 998GB Sector size (logical/physical): 512B/512B Partition Table: loop Number Start End Size File system Flags 1 0.00B 998GB 998GB ext4 I understand /dev/mapper/server--vg-root is the filesystem, and /dev/sda1 has some stuff related to GRUB. But, what about /dev/sda2 and /dev/sda5? When I tried to mount /dev/sda2, it said that I needed to specify the file system, which according to the table, is nonexistent. So, is it safe to format this with, say ext4 and mount it? Also, when I tried to mount /dev/sd5, it gave me this error: mount: unknown filesystem type 'LVM2_member' I assume it is NOT save to reformat this. If I'm wrong, then that would be great, because I could save some space. Please let me know either way. Thanks in advance! UPDATE: Here is the result of mount: /dev/mapper/server--vg-root on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none 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) /dev/sda1 on /boot type ext2 (rw,acl) /dev/sda1 on /media/hd2 type ext2 (rw)

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  • Mac OS X - Time Machine backup fails verification - What can I do to save the history?

    - by usermac75
    Hi, How do I make Time Machine to make a new complete backup without losing older versions of backed up files? Verbose: I am using the Time Machine backup on my OS X (Snow Leopard) to backup the whole computer to an external drive. I especially like the "history", i.e. the feature that allows you to restore the older version of a file. Problem: I had some data corruption on my external backup drive, I repaired it with the System Tool for doing that, it found some faults. I had the disk tool repair the external drive. After that, the external drive was OK and I could use Time Machine again. I let Time Machine do one more backup. Now I made a verification according to http://superuser.com/questions/47628/verifying-time-machine-backups, namely along sudo diff -qr . $HOME/Desktop 2>&1 | tee $HOME/timemachine-diff.log However: After doing the command above, several differences and missing files were reported, approx. 200 files in sum. Whereas some of the missing files were cache or excluded directories, the differences do bother me, especially as some important documents from me are listed as differing. How can I make sure that the data on the external drive is synced correctly? Is it possible to have Time Machine to do a complete new backup without losing the history? Or to have Time Machine compare all files for differences and re-write all files that are different? Or can I set some flags on the files that do not match to have them copied again? (like the archive-flag in Windows/Dos). I'd rather not touch the files because I would like to keep the date of last change/date of creation) Thank you for your thoughts!

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  • Benchmark Linq2SQL, Subsonic2, Subsonic3 - Any other ideas to make them faster ?

    - by Aristos
    I am working with Subsonic 2 more than 3 years now... After Linq appears and then Subsonic 3, I start thinking about moving to the new Linq futures that are connected to sql. I must say that I start move and port my subsonic 2 with SubSonic 3, and very soon I discover that the speed was so slow thats I didn't believe it - and starts all that tests. Then I test Linq2Sql and see also a delay - compare it with Subsonic 2. My question here is, especial for the linq2sql, and the up-coming dotnet version 4, what else can I do to speed it up ? What else on linq2sql settings, or classes, not on this code that I have used for my messures I place here the project that I make the tests, also the screen shots of the results. How I make the tests - and the accurate of my measures. I use only for my question Google chrome, because its difficult for me to show here a lot of other measures that I have done with more complex programs. This is the most simple one, I just measure the Data Read. How can I prove that. I make a simple Thread.Sleep(10 seconds) and see if I see that 10 seconds on Google Chrome Measure, and yes I see it. here are more test with this Sleep thead to see whats actually Chrome gives. 10 seconds delay 100 ms delay Zero delay There is only a small 15ms thats get on messure, is so small compare it with the rest of my tests that I do not care about. So what I measure I measure just the data read via each method - did not count the data or database delay, or any disk read or anything like that. Later on the image with the result I show that no disk activity exist on the measures See this image to see what really I measure and if this is correct Why I chose this kind of test Its simple, it's real, and it's near my real problem that I found the delay of subsonic 3 in real program with real data. Now lets tests the dals Start by see this image I have 4-5 calls on every method, the one after the other. The results are. For a loop of 100 times, ask for 5 Rows, one not exist, approximatively.. Simple adonet:81ms SubSonic 2 :210ms linq2sql :1.70sec linq2sql using CompiledQuery.Compile :239ms Subsonic 3 :15.00sec (wow - extreme slow) The project http://www.planethost.gr/DalSpeedTests.rar Can any one confirm this benchmark, or make any optimizations to help me out ? Other tests Some one publish here this link http://ormbattle.net/ (and then remove it - don not know why) In this page you can find a really useful advanced tests for all, except subsonic 2 and subsonic 3 that I have here ! Optimizing What I really ask here is if some one can now any trick how to optimize the DALs, not by changing the test code, but by changing the code and the settings on each dal. For example... Optimizing Linq2SQL I start search how to optimize Linq2sql and found this article, and maybe more exist. Finally I make the tricks from that page to run, and optimize the code using them all. The speed was near 1.50sec from 1.70.... big improvement, but still slow. Then I found a different way - same idea article, and wow ! the speed is blow up. Using this trick with CompiledQuery.Compile, the time from 1.5sec is now 239ms. Here is the code for the precompiled... Func<DataClassesDataContext, int, IQueryable<Product>> compiledQuery = CompiledQuery.Compile((DataClassesDataContext meta, int IdToFind) => (from myData in meta.Products where myData.ProductID.Equals(IdToFind) select myData)); StringBuilder Test = new StringBuilder(); int[] MiaSeira = { 5, 6, 10, 100, 7 }; using (DataClassesDataContext context = new DataClassesDataContext()) { context.ObjectTrackingEnabled = false; for (int i = 0; i < 100; i++) { foreach (int EnaID in MiaSeira) { var oFindThat2P = compiledQuery(context, EnaID); foreach (Product One in oFindThat2P) { Test.Append("<br />"); Test.Append(One.ProductName); } } } } Optimizing SubSonic 3 and problems I make many performance profiling, and start change the one after the other and the speed is better but still too slow. I post them on subsonic group but they ignore the problem, they say that everything is fast... Here is some capture of my profiling and delay points inside subsonic source code I have end up that subsonic3 make more call on the structure of the database rather than on data itself. Needs to reconsider the hole way of asking for data, and follow the subsonic2 idea if this is possible. Try to make precompile to subsonic 3 like I did in linq2Sql but fail for the moment... Optimizing SubSonic 2 After I discover that subsonic 3 is extreme slow, I start my checks on subsonic 2 - that I have never done before believing that is fast. (and it is) So its come up with some points that can be faster. For example there are many loops like this ones that actually is slow because of string manipulation and compares inside the loop. I must say to you that this code called million of times ! on a period of few minutes ! of data asking from the program. On small amount of tables and small fields maybe this is not a big think for some people, but on large amount of tables, the delay is even more. So I decide and optimize the subsonic 2 by my self, by replacing the string compares, with number compares! Simple. I do that almost on every point that profiler say that is slow. I change also all small points that can be even a little faster, and disable some not so used thinks. The results, 5% faster on NorthWind database, near 20% faster on my database with 250 tables. That is count with 500ms less in 10 seconds process on northwind, 100ms faster on my database on 500ms process time. I do not have captures to show you for that because I have made them with different code, different time, and track them down on paper. Anyway this is my story and my question on all that, what else do you know to make them even faster... For this measures I have use Subsonic 2.2 optimized by me, Subsonic 3.0.0.3 a little optimized by me, and Dot.Net 3.5

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  • Need guidance on a Google Map application that has to show 250 000 polylines.

    - by lucian.jp
    I am looking for advice for an application I am developing that uses Google Map. Summary: A user has a list of criteria for searching a street segment that fulfills the criteria. The street segments will be colored with 3 colors for showing those below average, average and over average. Then the user clicks on the street segment to see an information window showing the properties of that specific segment hiding those not selected until he/she closes the window and other polyline becomes visible again. This looks quite like the Monopoly City Streets game Hasbro made some month ago the difference being I do not use Flash, I can’t use Open Street Map because it doesn’t list street segment (if it does the IDs won’t be the same anyway) and I do not have to show Google sketch building over. Information: I have a database of street segments with IDs, polyline points and centroid. The database has 6,000,000 street segment records in it. To narrow the generated data a bit we focus on city. The largest city we must show has 250,000 street segments. This means 250,000 line segment polyline to show. Our longest polyline uses 9600 characters which is stored in two 8000 varchar columns in SQL Server 2008. We need to use the API v3 because it is faster than the API v2 and the application will be ported to iPhone. For now it's an ASP.NET 3.5 with SQl Server 2008 application. Performance is a priority. Problems: Most of the demo projects that do this are made with API v2. So besides tutorial on the Google API v3 reference page I have nothing to compare performance or technology use to achieve my goal. There is no available .NET wrapper for the API v3 yet. Generating a 250,000 line segment polyline creates a heavy file which takes time to transfer and parse. (I have found a demo of one polyline of 390,000 points. I think the encoder would be far less efficient with more polylines with less points since there will be less rounding.) Since streets segments are shown based on criteria, polylines must be dynamically created and cache can't be used. Some thoughts: KML/KMZ: Pros: Since it is a standard we can easily load Bing maps, Yahoo! maps, Google maps, Google Earth, with the same KML file. The data generation would be the same. Cons: LineString in KML cannot be encoded polyline like the Google map API can handle. So it would probably be bigger and slower to display. Zipping the file at the size it will take more processing time and require the client side to uncompress the data and I am not quite sure with 250,000 data how an iPhone would handle this and how a server would handle 40 users browsing at the same time. JavaScript file: Pros: JavaScript file can have encoded polyline and would significantly reduce the file to transfer. Cons: Have to create my own stripped version of API v3 to add overlays, create polyline, etc. It is more complex than just create a KML file and point to the source. GeoRSS: This option isn't adapted for my needs I think, but I could be wrong. MapServer: I saw some post suggesting using MapServer to generate overlays. Not quite sure for the connection with our database and the performance it would give. Plus it requires a plugin for generating KML. It seems to me that it wouldn't allow me to do better than creating my own KML or JavaScript file. Maintenance would be simpler without. Monopoly City Streets: The game is now over, but for those who know what I am talking about Monopoly City Streets was showing at max zoom level only the streets that the centroid was inside the Bounds of the window. Moving the map was sending request to the server for the new streets to show. While I think this was ingenious, I have no idea how to implement something similar. The only thing I thought about was to compare if the long was inside the bound of map area X and same with Y. While this could improve performance significantly at high zoom level, this would give nothing when showing a whole city. Clustering: While cluster is awesome for marker, it seems we cannot cluster polylines. I would have liked something like MarkerClusterer for polylines and be able to cluster by my 3 polyline colors. This will probably stay as a “would have been freaking awesome but forget it”. Arrow: I will have in a future version to show a direction for the polyline and will have to show an arrow at the centroid. Loading an image or marker will only double my data so creating a custom overlay will probably be my only option. I have found that demo for something similar I would like to achieve. Unfortunately, the demo is very slow, but I only wish to show 1 arrow per polyline and not multiple like the demo. This functionality will depend on the format of data since I don't think KML support custom overlays. Criteria: While the application is done with ASP.NET 3.5, the port to the iPhone won't use the web to show the application and be limited in screen size for selecting the criteria. This is why I was more orienting on a service or page generating the file based on criteria passed in parameters. The service would than generate the file I need to display the polylines on the map. I could also create an aspx page that does this. The aspx page is more documented than the service way. There should be a reason. Questions: Should I create a web service to returns the street segments file or create an aspx page that return the file? Should I create a JavaScript file with encoded polyline or a KML with longitude/latitude based on the fact that maximum longitude/latitude polyline have 9600 characters and I have to render maximum 250,000 line segment polyline. Or should I go with a MapServer that generate the overlay? Will I be able to display simple arrow on the polyline on the next version. In case of KML generation is it faster to create the file with XDocument, XmlDocument, XmlWriter and this manually or just serialize the street segment in the stream? This is more a brainstorming Stack Overflow question than an actual code problem. Any answer helping narrow the possibilities is as good as someone having all the knowledge to point me out a better choice.

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  • Asynchronous Webcrawling F#, something wrong ?

    - by jlezard
    Not quite sure if it is ok to do this but, my question is: Is there something wrong with my code ? It doesn't go as fast as I would like, and since I am using lots of async workflows maybe I am doing something wrong. The goal here is to build something that can crawl 20 000 pages in less than an hour. open System open System.Text open System.Net open System.IO open System.Text.RegularExpressions open System.Collections.Generic open System.ComponentModel open Microsoft.FSharp open System.Threading //This is the Parallel.Fs file type ComparableUri ( uri: string ) = inherit System.Uri( uri ) let elts (uri:System.Uri) = uri.Scheme, uri.Host, uri.Port, uri.Segments interface System.IComparable with member this.CompareTo( uri2 ) = compare (elts this) (elts(uri2 :?> ComparableUri)) override this.Equals(uri2) = compare this (uri2 :?> ComparableUri ) = 0 override this.GetHashCode() = 0 ///////////////////////////////////////////////Funtions to retreive html string////////////////////////////// let mutable error = Set.empty<ComparableUri> let mutable visited = Set.empty<ComparableUri> let getHtmlPrimitiveAsyncDelay (delay:int) (uri : ComparableUri) = async{ try let req = (WebRequest.Create(uri)) :?> HttpWebRequest // 'use' is equivalent to ‘using’ in C# for an IDisposable req.UserAgent<-"Mozilla" //Console.WriteLine("Waiting") do! Async.Sleep(delay * 250) let! resp = (req.AsyncGetResponse()) Console.WriteLine(uri.AbsoluteUri+" got response after delay "+string delay) use stream = resp.GetResponseStream() use reader = new StreamReader(stream) let html = reader.ReadToEnd() return html with | _ as ex -> Console.WriteLine( ex.ToString() ) lock error (fun () -> error<- error.Add uri ) lock visited (fun () -> visited<-visited.Add uri ) return "BadUri" } ///////////////////////////////////////////////Active Pattern Matching to retreive href////////////////////////////// let (|Matches|_|) (pat:string) (inp:string) = let m = Regex.Matches(inp, pat) // Note the List.tl, since the first group is always the entirety of the matched string. if m.Count > 0 then Some (List.tail [ for g in m -> g.Value ]) else None let (|Match|_|) (pat:string) (inp:string) = let m = Regex.Match(inp, pat) // Note the List.tl, since the first group is always the entirety of the matched string. if m.Success then Some (List.tail [ for g in m.Groups -> g.Value ]) else None ///////////////////////////////////////////////Find Bad href////////////////////////////// let isEmail (link:string) = link.Contains("@") let isMailto (link:string) = if Seq.length link >=6 then link.[0..5] = "mailto" else false let isJavascript (link:string) = if Seq.length link >=10 then link.[0..9] = "javascript" else false let isBadUri (link:string) = link="BadUri" let isEmptyHttp (link:string) = link="http://" let isFile (link:string)= if Seq.length link >=6 then link.[0..5] = "file:/" else false let containsPipe (link:string) = link.Contains("|") let isAdLink (link:string) = if Seq.length link >=6 then link.[0..5] = "adlink" elif Seq.length link >=9 then link.[0..8] = "http://adLink" else false ///////////////////////////////////////////////Find Bad href////////////////////////////// let getHref (htmlString:string) = let urlPat = "href=\"([^\"]+)" match htmlString with | Matches urlPat urls -> urls |> List.map( fun href -> match href with | Match (urlPat) (link::[]) -> link | _ -> failwith "The href was not in correct format, there was more than one match" ) | _ -> Console.WriteLine( "No links for this page" );[] |> List.filter( fun link -> not(isEmail link) ) |> List.filter( fun link -> not(isMailto link) ) |> List.filter( fun link -> not(isJavascript link) ) |> List.filter( fun link -> not(isBadUri link) ) |> List.filter( fun link -> not(isEmptyHttp link) ) |> List.filter( fun link -> not(isFile link) ) |> List.filter( fun link -> not(containsPipe link) ) |> List.filter( fun link -> not(isAdLink link) ) let treatAjax (href:System.Uri) = let link = href.ToString() let firstPart = (link.Split([|"#"|],System.StringSplitOptions.None)).[0] new Uri(firstPart) //only follow pages with certain extnsion or ones with no exensions let followHref (href:System.Uri) = let valid2 = set[".py"] let valid3 = set[".php";".htm";".asp"] let valid4 = set[".php3";".php4";".php5";".html";".aspx"] let arrLength = href.Segments |> Array.length let lastExtension = (href.Segments).[arrLength-1] let lengthLastExtension = Seq.length lastExtension if (lengthLastExtension <= 3) then not( lastExtension.Contains(".") ) else //test for the 2 case let last4 = lastExtension.[(lengthLastExtension-1)-3..(lengthLastExtension-1)] let isValid2 = valid2|>Seq.exists(fun validEnd -> last4.EndsWith( validEnd) ) if isValid2 then true else if lengthLastExtension <= 4 then not( last4.Contains(".") ) else let last5 = lastExtension.[(lengthLastExtension-1)-4..(lengthLastExtension-1)] let isValid3 = valid3|>Seq.exists(fun validEnd -> last5.EndsWith( validEnd) ) if isValid3 then true else if lengthLastExtension <= 5 then not( last5.Contains(".") ) else let last6 = lastExtension.[(lengthLastExtension-1)-5..(lengthLastExtension-1)] let isValid4 = valid4|>Seq.exists(fun validEnd -> last6.EndsWith( validEnd) ) if isValid4 then true else not( last6.Contains(".") ) && not(lastExtension.[0..5] = "mailto") //Create the correct links / -> add the homepage , make them a comparabel Uri let hrefLinksToUri ( uri:ComparableUri ) (hrefLinks:string list) = hrefLinks |> List.map( fun link -> try if Seq.length link <4 then Some(new Uri( uri, link )) else if link.[0..3] = "http" then Some(new Uri(link)) else Some(new Uri( uri, link )) with | _ as ex -> Console.WriteLine(link); lock error (fun () ->error<-error.Add uri) None ) |> List.filter( fun link -> link.IsSome ) |> List.map( fun o -> o.Value) |> List.map( fun uri -> new ComparableUri( string uri ) ) //Treat uri , removing ajax last part , and only following links specified b Benoit let linksToFollow (hrefUris:ComparableUri list) = hrefUris |>List.map( treatAjax ) |>List.filter( fun link -> followHref link ) |>List.map( fun uri -> new ComparableUri( string uri ) ) |>Set.ofList let needToVisit uri = ( lock visited (fun () -> not( visited.Contains uri) ) ) && (lock error (fun () -> not( error.Contains uri) )) let getLinksToFollowAsyncDelay (delay:int) ( uri: ComparableUri ) = async{ let! links = getHtmlPrimitiveAsyncDelay delay uri lock visited (fun () ->visited<-visited.Add uri) let linksToFollow = getHref links |> hrefLinksToUri uri |> linksToFollow |> Set.filter( needToVisit ) |> Set.map( fun link -> if uri.Authority=link.Authority then link else link ) return linksToFollow } //Add delays if visitng same authority let getDelay(uri:ComparableUri) (authorityDelay:Dictionary<string,int>) = let uriAuthority = uri.Authority let hasAuthority,delay = authorityDelay.TryGetValue(uriAuthority) if hasAuthority then authorityDelay.[uriAuthority] <-delay+1 delay else authorityDelay.Add(uriAuthority,1) 0 let rec getLinksToFollowFromSetAsync maxIteration ( uris: seq<ComparableUri> ) = let authorityDelay = Dictionary<string,int>() if maxIteration = 100 then Console.WriteLine("Finished") else //Unite by authority add delay for those we same authority others ignore let stopwatch= System.Diagnostics.Stopwatch() stopwatch.Start() let newLinks = uris |> Seq.map( fun uri -> let delay = lock authorityDelay (fun () -> getDelay uri authorityDelay ) getLinksToFollowAsyncDelay delay uri ) |> Async.Parallel |> Async.RunSynchronously |> Seq.concat stopwatch.Stop() Console.WriteLine("\n\n\n\n\n\n\nTimeElapse : "+string stopwatch.Elapsed+"\n\n\n\n\n\n\n\n\n") getLinksToFollowFromSetAsync (maxIteration+1) newLinks getLinksToFollowFromSetAsync 0 (seq[ComparableUri( "http://twitter.com/" )]) Console.WriteLine("Finished") Some feedBack would be great ! Thank you (note this is just something I am doing for fun)

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  • Suggestions for duplicate file finder algorithm (using C)

    - by Andrei Ciobanu
    Hello, I wanted to write a program that test if two files are duplicates (have exactly the same content). First I test if the files have the same sizes, and if they have i start to compare their contents. My first idea, was to "split" the files into fixed size blocks, then start a thread for every block, fseek to startup character of every block and continue the comparisons in parallel. When a comparison from a thread fails, the other working threads are canceled, and the program exits out of the thread spawning loop. The code looks like this: dupf.h #ifndef __NM__DUPF__H__ #define __NM__DUPF__H__ #define NUM_THREADS 15 #define BLOCK_SIZE 8192 /* Thread argument structure */ struct thread_arg_s { const char *name_f1; /* First file name */ const char *name_f2; /* Second file name */ int cursor; /* Where to seek in the file */ }; typedef struct thread_arg_s thread_arg; /** * 'arg' is of type thread_arg. * Checks if the specified file blocks are * duplicates. */ void *check_block_dup(void *arg); /** * Checks if two files are duplicates */ int check_dup(const char *name_f1, const char *name_f2); /** * Returns a valid pointer to a file. * If the file (given by the path/name 'fname') cannot be opened * in 'mode', the program is interrupted an error message is shown. **/ FILE *safe_fopen(const char *name, const char *mode); #endif dupf.c #include <errno.h> #include <pthread.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> #include "dupf.h" FILE *safe_fopen(const char *fname, const char *mode) { FILE *f = NULL; f = fopen(fname, mode); if (f == NULL) { char emsg[255]; sprintf(emsg, "FOPEN() %s\t", fname); perror(emsg); exit(-1); } return (f); } void *check_block_dup(void *arg) { const char *name_f1 = NULL, *name_f2 = NULL; /* File names */ FILE *f1 = NULL, *f2 = NULL; /* Streams */ int cursor = 0; /* Reading cursor */ char buff_f1[BLOCK_SIZE], buff_f2[BLOCK_SIZE]; /* Character buffers */ int rchars_1, rchars_2; /* Readed characters */ /* Initializing variables from 'arg' */ name_f1 = ((thread_arg*)arg)->name_f1; name_f2 = ((thread_arg*)arg)->name_f2; cursor = ((thread_arg*)arg)->cursor; /* Opening files */ f1 = safe_fopen(name_f1, "r"); f2 = safe_fopen(name_f2, "r"); /* Setup cursor in files */ fseek(f1, cursor, SEEK_SET); fseek(f2, cursor, SEEK_SET); /* Initialize buffers */ rchars_1 = fread(buff_f1, 1, BLOCK_SIZE, f1); rchars_2 = fread(buff_f2, 1, BLOCK_SIZE, f2); if (rchars_1 != rchars_2) { /* fread failed to read the same portion. * program cannot continue */ perror("ERROR WHEN READING BLOCK"); exit(-1); } while (rchars_1-->0) { if (buff_f1[rchars_1] != buff_f2[rchars_1]) { /* Different characters */ fclose(f1); fclose(f2); pthread_exit("notdup"); } } /* Close streams */ fclose(f1); fclose(f2); pthread_exit("dup"); } int check_dup(const char *name_f1, const char *name_f2) { int num_blocks = 0; /* Number of 'blocks' to check */ int num_tsp = 0; /* Number of threads spawns */ int tsp_iter = 0; /* Iterator for threads spawns */ pthread_t *tsp_threads = NULL; thread_arg *tsp_threads_args = NULL; int tsp_threads_iter = 0; int thread_c_res = 0; /* Thread creation result */ int thread_j_res = 0; /* Thread join res */ int loop_res = 0; /* Function result */ int cursor; struct stat buf_f1; struct stat buf_f2; if (name_f1 == NULL || name_f2 == NULL) { /* Invalid input parameters */ perror("INVALID FNAMES\t"); return (-1); } if (stat(name_f1, &buf_f1) != 0 || stat(name_f2, &buf_f2) != 0) { /* Stat fails */ char emsg[255]; sprintf(emsg, "STAT() ERROR: %s %s\t", name_f1, name_f2); perror(emsg); return (-1); } if (buf_f1.st_size != buf_f2.st_size) { /* File have different sizes */ return (1); } /* Files have the same size, function exec. is continued */ num_blocks = (buf_f1.st_size / BLOCK_SIZE) + 1; num_tsp = (num_blocks / NUM_THREADS) + 1; cursor = 0; for (tsp_iter = 0; tsp_iter < num_tsp; tsp_iter++) { loop_res = 0; /* Create threads array for this spawn */ tsp_threads = malloc(NUM_THREADS * sizeof(*tsp_threads)); if (tsp_threads == NULL) { perror("TSP_THREADS ALLOC FAILURE\t"); return (-1); } /* Create arguments for every thread in the current spawn */ tsp_threads_args = malloc(NUM_THREADS * sizeof(*tsp_threads_args)); if (tsp_threads_args == NULL) { perror("TSP THREADS ARGS ALLOCA FAILURE\t"); return (-1); } /* Initialize arguments and create threads */ for (tsp_threads_iter = 0; tsp_threads_iter < NUM_THREADS; tsp_threads_iter++) { if (cursor >= buf_f1.st_size) { break; } tsp_threads_args[tsp_threads_iter].name_f1 = name_f1; tsp_threads_args[tsp_threads_iter].name_f2 = name_f2; tsp_threads_args[tsp_threads_iter].cursor = cursor; thread_c_res = pthread_create( &tsp_threads[tsp_threads_iter], NULL, check_block_dup, (void*)&tsp_threads_args[tsp_threads_iter]); if (thread_c_res != 0) { perror("THREAD CREATION FAILURE"); return (-1); } cursor+=BLOCK_SIZE; } /* Join last threads and get their status */ while (tsp_threads_iter-->0) { void *thread_res = NULL; thread_j_res = pthread_join(tsp_threads[tsp_threads_iter], &thread_res); if (thread_j_res != 0) { perror("THREAD JOIN FAILURE"); return (-1); } if (strcmp((char*)thread_res, "notdup")==0) { loop_res++; /* Closing other threads and exiting by condition * from loop. */ while (tsp_threads_iter-->0) { pthread_cancel(tsp_threads[tsp_threads_iter]); } } } free(tsp_threads); free(tsp_threads_args); if (loop_res > 0) { break; } } return (loop_res > 0) ? 1 : 0; } The function works fine (at least for what I've tested). Still, some guys from #C (freenode) suggested that the solution is overly complicated, and it may perform poorly because of parallel reading on hddisk. What I want to know: Is the threaded approach flawed by default ? Is fseek() so slow ? Is there a way to somehow map the files to memory and then compare them ?

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