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  • Have I pushed the limits of my current VPS or is there room for optimization?

    - by JRameau
    I am currently on a mediatemple DV server (basic) 512mb dedicated ram, this is a CentOS based VPS with Plesk and Virtuozzo. My experience with it from day 1 has been bad and I only could sooth my server issues with several caching "Band-aids," but my sites are not as small as they were a year ago either so the issues have worsen. I have 3 Drupal installs running on separate (plesk) domains, 1 of those drupal installs is a multisite, that consists of 5-6 sites 2 of those sites are bringing in actual traffic. Those caching "Band-aids" I mentioned are APC, which seemed to help alot initially, and Drupal's Boost, which is considered a poorman's Varnish, it makes all my pages static for anonymous users. Last 30day combined estimate on Google Ananlytics: 90k visitors 260k pageviews. Issue: alot of downtime, I am continually checking if my sites are up, and lately I have been finding it down more than 3 times daily. Restarting Apache will bring it back up, for some time. I have google search every error message and looked up ways to optimize my DV server, and I am beyond stump what is my next move. Is this server bad, have I hit a impossibly low restriction such as the 12mb kernel memory barrier (kmemsize), is it on my end, do I need to optimize some more? *I have provided as much information as I can below, any help or suggestions given will be appreciated Common Error messages I see in the log: [error] (12)Cannot allocate memory: fork: Unable to fork new process [error] make_obcallback: could not import mod_python.apache.\n Traceback (most recent call last): File "/usr/lib/python2.4/site-packages/mod_python/apache.py", line 21, in ? import traceback File "/usr/lib/python2.4/traceback.py", line 3, in ? import linecache ImportError: No module named linecache [error] python_handler: no interpreter callback found. [warn-phpd] mmap cache can't open /var/www/vhosts/***/httpdocs/*** - Too many open files in system (pid ***) [alert] Child 8125 returned a Fatal error... Apache is exiting! [emerg] (43)Identifier removed: couldn't grab the accept mutex [emerg] (22)Invalid argument: couldn't release the accept mutex cat /proc/user_beancounters: Version: 2.5 uid resource held maxheld barrier limit failcnt 41548: kmemsize 4582652 5306699 12288832 13517715 21105036 lockedpages 0 0 600 600 0 privvmpages 38151 42676 229036 249036 0 shmpages 16274 16274 17237 17237 2 dummy 0 0 0 0 0 numproc 43 46 300 300 0 physpages 27260 29528 0 2147483647 0 vmguarpages 0 0 131072 2147483647 0 oomguarpages 27270 29538 131072 2147483647 0 numtcpsock 21 29 300 300 0 numflock 8 8 480 528 0 numpty 1 1 30 30 0 numsiginfo 0 1 1024 1024 0 tcpsndbuf 648440 675272 2867477 4096277 1711499 tcprcvbuf 301620 359716 2867477 4096277 0 othersockbuf 4472 4472 1433738 2662538 0 dgramrcvbuf 0 0 1433738 1433738 0 numothersock 12 12 300 300 0 dcachesize 0 0 2684271 2764800 0 numfile 3447 3496 6300 6300 3872 dummy 0 0 0 0 0 dummy 0 0 0 0 0 dummy 0 0 0 0 0 numiptent 14 14 200 200 0 TOP: (In January the load avg was really high 3-10, I was able to bring it down where it is currently is by giving APC more memory play around with) top - 16:46:07 up 2:13, 1 user, load average: 0.34, 0.20, 0.20 Tasks: 40 total, 2 running, 37 sleeping, 0 stopped, 1 zombie Cpu(s): 0.3% us, 0.1% sy, 0.0% ni, 99.7% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 916144k total, 156668k used, 759476k free, 0k buffers Swap: 0k total, 0k used, 0k free, 0k cached MySQLTuner: (after optimizing every table and repairing any table with overage I got the fragmented count down to 86) [--] Data in MyISAM tables: 285M (Tables: 1105) [!!] Total fragmented tables: 86 [--] Up for: 2h 44m 38s (409K q [41.421 qps], 6K conn, TX: 1B, RX: 174M) [--] Reads / Writes: 79% / 21% [--] Total buffers: 58.0M global + 2.7M per thread (100 max threads) [!!] Query cache prunes per day: 675307 [!!] Temporary tables created on disk: 35% (7K on disk / 20K total)

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  • Tomcat dying silently on regular basis

    - by Hendrik
    My tomcat (6.0.32, Java Sun 1.6.0_22-b04 on Ubuntu 10.04) keeps crashing multiple times daily without any specific output in catalina.out. This usually happens on high load (see top output). Update: The pid-file is properly removed when this happens. Update 2: No CATALINA_OPTS set, _JAVA_OPTS are: export _JAVA_OPTIONS="-Xms128m -Xmx1024m -XX:MaxPermSize=512m \ -XX:MinHeapFreeRatio=20 \ -XX:MaxHeapFreeRatio=40 \ -XX:NewSize=10m \ -XX:MaxNewSize=10m \ -XX:SurvivorRatio=6 \ -XX:TargetSurvivorRatio=80 \ -XX:+CMSClassUnloadingEnabled \ -Djava.awt.headless=true \ -Dcom.sun.management.jmxremote \ -Dcom.sun.management.jmxremote.port=37331 \ -Dcom.sun.management.jmxremote.ssl=false \ -Dcom.sun.management.jmxremote.authenticate=true \ -Djava.rmi.server.hostname=(myhostname) \ -Dcom.sun.management.jmxremote.password.file=/etc/java-6-sun/management/jmxremote.password \ -Dcom.sun.management.jmxremote.access.file=/etc/java-6-sun/management/jmxremote.access" Top: top - 12:40:03 up 9 days, 12:15, 3 users, load average: 30.00, 22.39, 21.91 Tasks: 89 total, 4 running, 85 sleeping, 0 stopped, 0 zombie Cpu(s): 53.2%us, 9.7%sy, 0.0%ni, 34.7%id, 1.5%wa, 0.0%hi, 0.8%si, 0.0%st Mem: 4194304k total, 3311304k used, 883000k free, 0k buffers Swap: 4194304k total, 0k used, 4194304k free, 0k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 25850 tomcat6 20 0 1981m 1.2g 11m S 161 29.6 11:41.56 java 12632 mysql 20 0 393m 97m 4452 S 141 2.4 1690:05 mysqld 14932 nobody 20 0 253m 44m 9152 R 56 1.1 3:26.57 php-cgi 7011 nobody 20 0 241m 31m 9124 S 30 0.8 1:35.96 php-cgi 10093 nobody 20 0 228m 18m 8520 S 25 0.5 2:29.97 php-cgi 27071 nobody 20 0 237m 28m 8640 S 11 0.7 3:13.72 php-cgi 3306 nobody 20 0 227m 16m 6736 R 7 0.4 2:29.83 php-cgi 7756 nobody 20 0 261m 58m 15m R 5 1.4 2:22.33 php-cgi 7129 www-data 20 0 3646m 7228 1896 S 2 0.2 0:36.65 nginx 2657 nobody 20 0 228m 18m 8540 S 1 0.5 1:59.51 php-cgi 7131 www-data 20 0 3645m 6464 1960 S 1 0.2 0:34.13 nginx 7140 www-data 20 0 3652m 12m 1896 S 1 0.3 0:35.80 nginx 619 nobody 20 0 231m 29m 15m S 0 0.7 2:33.46 php-cgi 16552 nobody 20 0 250m 41m 8784 S 0 1.0 2:48.12 php-cgi 17134 nobody 20 0 239m 37m 16m S 0 0.9 2:32.86 php-cgi 21004 nobody 20 0 243m 34m 8700 S 0 0.8 1:19.85 php-cgi 26105 root 20 0 19220 1392 1060 R 0 0.0 0:00.82 top 32430 nobody 20 0 256m 47m 9196 S 0 1.2 2:19.01 php-cgi 314 nobody 20 0 256m 47m 8804 S 0 1.1 1:46.00 php-cgi 2111 nobody 20 0 253m 44m 9196 S 0 1.1 3:01.14 php-cgi 2142 root 20 0 26452 2564 868 S 0 0.1 0:00.56 screen 2144 root 20 0 19484 2012 1368 S 0 0.0 0:00.00 bash 2333 nobody 20 0 249m 41m 9160 S 0 1.0 1:10.33 php-cgi 2552 root 20 0 19484 2260 1620 S 0 0.1 0:00.01 bash 2587 nobody 20 0 258m 49m 9192 S 0 1.2 2:04.50 php-cgi 2684 root 20 0 4092 652 540 S 0 0.0 0:00.00 xvfb-run 2696 root 20 0 60720 13m 2352 S 0 0.3 0:09.12 Xvfb 2759 root 20 0 617m 12m 4676 S 0 0.3 0:00.66 node 3514 nobody 20 0 270m 61m 9216 S 0 1.5 3:13.69 php-cgi 5270 root 20 0 25164 1324 1036 S 0 0.0 0:00.01 screen 5402 nobody 20 0 227m 16m 8032 S 0 0.4 1:33.61 php-cgi 5765 root 20 0 81180 3820 3028 S 0 0.1 0:00.31 sshd 5798 nobody 20 0 242m 32m 9124 S 0 0.8 1:52.08 php-cgi 5856 root 20 0 19496 2292 1636 S 0 0.1 0:00.03 bash 6442 root 20 0 62332 20m 1960 S 0 0.5 0:30.58 mrtg 7082 root 20 0 88992 1916 1636 S 0 0.0 0:00.00 PassengerWatchd I can't find any concrete reason for it, no Exceptions or messages of a shutdown in catalina.out (and no other logs in tomcat's log dir). I can start up the service and it will run for a few days or just minutes before dying again. Is there somewhere else i could look for output? Could the kernel start killing threads due to a lack of ressources and by that bring the VM down?

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  • NFS Mounts Issues

    - by user554005
    Having some issue with a NFS Setup on the clients it just times out refuses to connect [root@host9 ~]# mount 192.168.0.17:/home/export /mnt/export mount: mount to NFS server '192.168.0.17' failed: timed out (retrying). mount: mount to NFS server '192.168.0.17' failed: timed out (retrying). mount: mount to NFS server '192.168.0.17' failed: timed out (retrying). mount: mount to NFS server '192.168.0.17' failed: timed out (retrying). Here are the settings I'm using: [root@host17 /home/export]# cat /etc/hosts.allow # # hosts.allow This file contains access rules which are used to # allow or deny connections to network services that # either use the tcp_wrappers library or that have been # started through a tcp_wrappers-enabled xinetd. # # See 'man 5 hosts_options' and 'man 5 hosts_access' # for information on rule syntax. # See 'man tcpd' for information on tcp_wrappers # portmap: 192.168.0.0/255.255.255.0 lockd: 192.168.0.0/255.255.255.0 rquotad: 192.168.0.0/255.255.255.0 mountd: 192.168.0.0/255.255.255.0 statd: 192.168.0.0/255.255.255.0 [root@host17 /home/export]# cat /etc/hosts.deny # # hosts.deny This file contains access rules which are used to # deny connections to network services that either use # the tcp_wrappers library or that have been # started through a tcp_wrappers-enabled xinetd. # # The rules in this file can also be set up in # /etc/hosts.allow with a 'deny' option instead. # # See 'man 5 hosts_options' and 'man 5 hosts_access' # for information on rule syntax. # See 'man tcpd' for information on tcp_wrappers # portmap:ALL lockd:ALL mountd:ALL rquotad:ALL statd:ALL [root@host17 /home/export]# cat /etc/exports /home/export 192.168.0.0/255.255.255.0(rw) [root@host17 /home/export]# iptables -L Chain INPUT (policy ACCEPT) target prot opt source destination RH-Firewall-1-INPUT all -- anywhere anywhere Chain FORWARD (policy ACCEPT) target prot opt source destination RH-Firewall-1-INPUT all -- anywhere anywhere Chain OUTPUT (policy ACCEPT) target prot opt source destination Chain RH-Firewall-1-INPUT (2 references) target prot opt source destination ACCEPT all -- anywhere anywhere ACCEPT icmp -- anywhere anywhere icmp any ACCEPT esp -- anywhere anywhere ACCEPT ah -- anywhere anywhere ACCEPT udp -- anywhere 224.0.0.251 udp dpt:mdns ACCEPT udp -- anywhere anywhere udp dpt:ipp ACCEPT tcp -- anywhere anywhere tcp dpt:ipp ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:ssh ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:http ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:https ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:6379 ACCEPT udp -- 192.168.0.0/24 anywhere state NEW udp dpt:sunrpc ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:sunrpc ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:nfs ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:32803 ACCEPT udp -- 192.168.0.0/24 anywhere state NEW udp dpt:filenet-rpc ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:892 ACCEPT udp -- 192.168.0.0/24 anywhere state NEW udp dpt:892 ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:rquotad ACCEPT udp -- 192.168.0.0/24 anywhere state NEW udp dpt:rquotad ACCEPT tcp -- 192.168.0.0/24 anywhere state NEW tcp dpt:pftp ACCEPT udp -- 192.168.0.0/24 anywhere state NEW udp dpt:pftp REJECT all -- anywhere anywhere reject-with icmp-host-prohibited on the clients here is some rpcinfos [root@host9 ~]# rpcinfo -p 192.168.0.17 program vers proto port 100000 4 tcp 111 portmapper 100000 3 tcp 111 portmapper 100000 2 tcp 111 portmapper 100000 4 udp 111 portmapper 100000 3 udp 111 portmapper 100000 2 udp 111 portmapper 100011 1 udp 875 rquotad 100011 2 udp 875 rquotad 100011 1 tcp 875 rquotad 100011 2 tcp 875 rquotad 100005 1 udp 45857 mountd 100005 1 tcp 55772 mountd 100005 2 udp 34021 mountd 100005 2 tcp 59542 mountd 100005 3 udp 60930 mountd 100005 3 tcp 53086 mountd 100003 2 udp 2049 nfs 100003 3 udp 2049 nfs 100003 4 udp 2049 nfs 100227 2 udp 2049 nfs_acl 100227 3 udp 2049 nfs_acl 100003 2 tcp 2049 nfs 100003 3 tcp 2049 nfs 100003 4 tcp 2049 nfs 100227 2 tcp 2049 nfs_acl 100227 3 tcp 2049 nfs_acl 100021 1 udp 59832 nlockmgr 100021 3 udp 59832 nlockmgr 100021 4 udp 59832 nlockmgr 100021 1 tcp 36140 nlockmgr 100021 3 tcp 36140 nlockmgr 100021 4 tcp 36140 nlockmgr 100024 1 udp 46494 status 100024 1 tcp 49672 status [root@host9 ~]# [root@host9 ~]# rpcinfo -u 192.168.0.17 nfs rpcinfo: RPC: Timed out program 100003 version 0 is not available [root@host9 ~]# rpcinfo -u 192.168.0.17 portmap program 100000 version 2 ready and waiting program 100000 version 3 ready and waiting program 100000 version 4 ready and waiting [root@host9 ~]# rpcinfo -u 192.168.0.17 mount rpcinfo: RPC: Timed out program 100005 version 0 is not available [root@host9 ~]# I'm running CentOS 5.8 on all systems

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  • SSH-forwarded X11 display from Linux to Mac lost after some time

    - by mklein9
    I have a new and vexing problem with ssh forwarding my X11 connection when logging in from a Mac (10.7.2) to Linux (Ubuntu 8.04). I have no trouble using ssh -X to log in to the remote machine and starting an X11-based application from that shell. What has recently started happening is that additional invocations of X11 applications from that same shell, after a while (on the order of hours), are unable to start because the forwarded display is being blocked (I presume). When attempting to start xterm, for example, I get the usual message about a bad DISPLAY setting, such as: xterm Xt error: Can't open display: localhost:10.0 But the X11 application I started right when I logged in is still running along just fine, using that exact same display (localhost:10.0), just that it was started earlier. I turned on verbose logging in sshd_config and I see this in the /var/log/auth.log file in response to the failed xterm startup attempt: sshd[22104]: channel 8: open failed: administratively prohibited: open failed If I ssh -X to the server again, starting a new shell and getting assigned a new display (localhost:11.0), the same process repeats: the X11 applications started early on run just fine for as long as I keep them open (days), but after a few hours I cannot start any new ones from that shell. Particulars: OpenSSH sshd server running on Ubuntu 8.04, display forwarded to a Mac running Lion (10.7.2) with the default Apple X server. The systems are connected on an Ethernet LAN with a single switch between them. Neither machine is running a firewall. Until recently (a few days ago) this setup worked perfectly so I am mystified as to where to look next. I am by no means an X11 or SSH expert but have good UNIX/Linux experience. Nothing obvious has changed in either client or server configuration although I have tried changing a few options to try to debug this, like setting sshd_config's TCPKeepAlive to no, and setting "host +localhost" (you can tell I've been Googling). When logging in from a Linux 11.10 laptop to the same remote host over the same network and switch, this problem does not occur -- an xterm can be invoked successfully hours later from the same ssh login shell while the same experiment from the Mac fails (tested this morning to be sure), so it would appear to be a Mac-specific issue. With "LogLevel DEBUG3" set on the remote machine (sshd server), and no change made in the client connections by me, /var/log/auth.log shows one slight change in connection status reports overnight, which is the port number used by the one successful ssh session from the Linux machine (I think), connection #7 below: sshd[20173]: debug3: channel 7: status: The following connections are open:\r\n #0 server-session (t4 r0 i0/0 o0/0 fd 14/13 cfd -1)\r\n #3 X11 connection from 127.0.0.1 port 57564 (t4 r1 i0/0 o0/0 fd 16/16 cfd -1)\r\n #4 X11 connection from 127.0.0.1 port 57565 (t4 r2 i0/0 o0/0 fd 17/17 cfd -1)\r\n #5 X11 connection from 127.0.0.1 port 57566 (t4 r3 i0/0 o0/0 fd 18/18 cfd -1)\r\n #6 X11 connection from 127.0.0.1 port 57567 (t4 r4 i0/0 o0/0 fd 19/19 cfd -1)\r\n #7 X11 connection from 127.0.0.1 port 59007 In this report, everything is the same between status reports except the port number used by connection #7 which I believe is the Linux client -- the only one still maintaining a display connection. It continues to increment over time, judging by a sequence of these reports overnight. Thanks for any help, -Mike

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  • What Apache/PHP configurations do you know and how good are they?

    - by FractalizeR
    Hello. I wanted to ask you about PHP/Apache configuration methods you know, their pros and cons. I will start myself: ---------------- PHP as Apache module---------------- Pros: good speed since you don't need to start exe every time especially in mpm-worker mode. You can also use various PHP accelerators in this mode like APC or eAccelerator. Cons: if you are running apache in mpm-worker mode, you may face stability issues because every glitch in any php script will lead to unstability to the whole thread pool of that apache process. Also in this mode all scripts are executed on behalf of apache user. This is bad for security. mpm-worker configuration requires PHP compiled in thread-safe mode. At least CentOS and RedHat default repositories doesn't have thread-safe PHP version so on these OSes you need to compile at least PHP yourself (there is a way to activate worker mpm on Apache). The use of thread-safe PHP binaries is considered experimental and unstable. Plus, many PHP extensions does not support thread-safe mode or were not well-tested in thread-safe mode. ---------------- PHP as CGI ---------------- This seems to be the slowest default configuration which seems to be a "con" itself ;) ---------------- PHP as CGI via mod_suphp ---------------- Pros: suphp allows you to execute php scipts on behalf of the script file owner. This way you can securely separate different sites on the same machine. Also, suphp allows to use different php.ini files per virtual host. Cons: PHP in CGI mode means less performance. In this mode you can't use php accelerators like APC because each time new process is spawned to handle script rendering the cache of previous process useless. BTW, do you know the way to apply some accelerator in this config? I heard something about using shm for php bytecode cache. Also, you cannot configure PHP via .htaccess files in this mode. You will need to install PECL htscanner for this if you need to set various per-script options via .htaccess (php_value / php_flag directives) ---------------- PHP as CGI via suexec ---------------- This configuration looks the same as with suphp, but I heard, that it's slower and less safe. Almost same pros and cons apply. ---------------- PHP as FastCGI ---------------- Pros: FastCGI standard allows single php process to handle several scripts before php process is killed. This way you gain performance since no need to spin up new php process for each script. You can also use PHP accelerators in this configuration (see cons section for comment). Also, FCGI almost like suphp also allows php processes to be executed on behalf of some user. mod_fcgid seems to have the most complete fcgi support and flexibility for apache. Cons: The use of php accelerator in fastcgi mode will lead to high memory consumption because each PHP process will have his own bytecode cache (unless there is some accelerator that can use shared memory for bytecode cache. Is there such?). FastCGI is also a little bit complex to configure. You need to create various configuration files and make some configuration modifications. It seems, that fastcgi is the most stable, secure, fast and flexible PHP configuration, however, a bit difficult to be configured. But, may be, I missed something? Comments are welcome!

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  • GNU/Linux swapping blocks system

    - by Ole Tange
    I have used GNU/Linux on systems from 4 MB RAM to 512 GB RAM. When they start swapping, most of the time you can still log in and kill off the offending process - you just have to be 100-1000 times more patient. On my new 32 GB system that has changed: It blocks when it starts swapping. Sometimes with full disk activity but other times with no disk activity. To examine what might be the issue I have written this program. The idea is: 1 grab 3% of the memory free right now 2 if that caused swap to increase: stop 3 keep the chunk used for 30 seconds by forking off 4 goto 1 - #!/usr/bin/perl sub freekb { my $free = `free|grep buffers/cache`; my @a=split / +/,$free; return $a[3]; } sub swapkb { my $swap = `free|grep Swap:`; my @a=split / +/,$swap; return $a[2]; } my $swap = swapkb(); my $lastswap = $swap; my $free; while($lastswap >= $swap) { print "$swap $free"; $lastswap = $swap; $swap = swapkb(); $free = freekb(); my $used_mem = "x"x(1024 * $free * 0.03); if(not fork()) { sleep 30; exit(); } } print "Swap increased $swap $lastswap\n"; Running the program forever ought to keep the system at the limit of swapping, but only grabbing a minimal amount of swap and do that very slowly (i.e. a few MB at a time at most). If I run: forever free | stdbuf -o0 timestamp > freelog I ought to see swap slowly rising every second. (forever and timestamp from https://github.com/ole-tange/tangetools). But that is not the behaviour I see: I see swap increasing in jumps and that the system is completely blocked during these jumps. Here the system is blocked for 30 seconds with the swap usage increases with 1 GB: secs 169.527 Swap: 18440184 154184 18286000 170.531 Swap: 18440184 154184 18286000 200.630 Swap: 18440184 1134240 17305944 210.259 Swap: 18440184 1076228 17363956 Blocked: 21 secs. Swap increase 2400 MB: 307.773 Swap: 18440184 581324 17858860 308.799 Swap: 18440184 597676 17842508 330.103 Swap: 18440184 2503020 15937164 331.106 Swap: 18440184 2502936 15937248 Blocked: 20 secs. Swap increase 2200 MB: 751.283 Swap: 18440184 885288 17554896 752.286 Swap: 18440184 911676 17528508 772.331 Swap: 18440184 3193532 15246652 773.333 Swap: 18440184 1404540 17035644 Blocked: 37 secs. Swap increase 2400 MB: 904.068 Swap: 18440184 613108 17827076 905.072 Swap: 18440184 610368 17829816 942.424 Swap: 18440184 3014668 15425516 942.610 Swap: 18440184 2073580 16366604 This is bad enough, but what is even worse is that the system sometimes stops responding at all - even if I wait for hours. I have the feeling it is related to the swapping issue, but I cannot tell for sure. My first idea was to tweak /proc/sys/vm/swappiness from 60 to 0 or 100, just to see if that had any effect at all. 0 did not have an effect, but 100 did cause the problem to arise less often. How can I prevent the system from blocking for such a long time? Why does it decide to swapout 1-3 GB when less than 10 MB would suffice?

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  • Is the Cloud ready for an Enterprise Java web application? Seeking a JEE hosting advice.

    - by Jakub Holý
    Greetings to all the smart people around here! I'd like to ask whether it is feasible or a good idea at all to deploy a Java enterprise web application to a Cloud such as Amazon EC2. More exactly, I'm looking for infrastructure options for an application that shall handle few hundred users with long but neither CPU nor memory intensive sessions. I'm considering dedicated servers, virtual private servers (VPSs) and EC2. I've noticed that there is a project called JBoss Cloud so people are working on enabling such a deployment, on the other hand it doesn't seem to be mature yet and I'm not sure that the cloud is ready for this kind of applications, which differs from the typical cloud-based applications like Twitter. Would you recommend to deploy it to the cloud? What are the pros and cons? The application is a Java EE 5 web application whose main function is to enable users to compose their own customized Product by combining the available Parts. It uses stateless and stateful session beans and JPA for persistence of entities to a RDBMS and fetches information about Parts from the company's inventory system via a web service. Aside of external users it's used also by few internal ones, who are authenticated against the company's LDAP. The application should handle around 300-400 concurrent users building their product and should be reasonably scalable and available though these qualities are only of a medium importance at this stage. I've proposed an architecture consisting of a firewall (FW) and load balancer supporting sticky sessions and https (in the Cloud this would be replaced with EC2's Elastic Load Balancing service and FW on the app. servers, in a physical architecture the load-balancer would be a HW), then two physical clustered application servers combined with web servers (so that if one fails, a user doesn't loose his/her long built product) and finally a database server. The DB server would need a slave backup instance that can replace the master instance if it fails. This should provide reasonable availability and fault tolerance and provide good scalability as long as a single RDBMS can keep with the load, which should be OK for quite a while because most of the operations are done in the memory using a stateful bean and only occasionally stored or retrieved from the DB and the amount of data is low too. A problematic part could be the dependency on the remote inventory system webservice but with good caching of its outputs in the application it should be OK too. Unfortunately I've only vague idea of the system resources (memory size, number and speed of CPUs/cores) that such an "average Java EE application" for few hundred users needs. My rough and mostly unfounded estimate based on actual Amazon offerings is that 1.7GB and a single, 2-core "modern CPU" with speed around 2.5GHz (the High-CPU Medium Instance) should be sufficient for any of the two application servers (since we can handle higher load by provisioning more of them). Alternatively I would consider using the Large instance (64b, 7.5GB RAM, 2 cores at 1GHz) So my question is whether such a deployment to the cloud is technically and financially feasible or whether dedicated/VPS servers would be a better option and whether there are some real-world experiences with something similar. Thank you very much! /Jakub Holy PS: I've found the JBoss EAP in a Cloud Case Study that shows that it is possible to deploy a real-world Java EE application to the EC2 cloud but unfortunately there're no details regarding topology, instance types, or anything :-(

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  • Unable to make the session state request to the session state server

    - by Angry_IT_Guru
    For about 4-5 months now, I seem to be having this sporadic issue--mainly during our busiest time of the day between 10:30-11:45AM, where all my Windows 2003 web servers in a Microsoft NLB cluster start throwing session state server errors. A sample error is below. System.Web.HttpException: Unable to make the session state request to the session state server. Please ensure that the ASP.NET State service is started and that the client and server ports are the same. If the server is on a remote machine, please ensure that it accepts remote requests by checking the value of HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\aspnet_state\Parameters\AllowRemoteConnection. If the server is on the local machine, and if the before mentioned registry value does not exist or is set to 0, then the state server connection string must use either 'localhost' or '127.0.0.1' as the server name. at System.Web.SessionState.OutOfProcSessionStateStore.MakeRequest(StateProtocolVerb verb, String id, StateProtocolExclusive exclusiveAccess, Int32 extraFlags, Int32 timeout, Int32 lockCookie, Byte[] buf, Int32 cb, Int32 networkTimeout, SessionNDMakeRequestResults& results) at System.Web.SessionState.OutOfProcSessionStateStore.SetAndReleaseItemExclusive(HttpContext context, String id, SessionStateStoreData item, Object lockId, Boolean newItem) at System.Web.SessionState.SessionStateModule.OnReleaseState(Object source, EventArgs eventArgs) at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) Now I'm using ASP.NET State service on a centralized back-end Windows 2003 server that all servers communicate to. I was originally using SQL Server state for a couple years as well prior to having this issue. The problem with SQL wqas that when the issue occurred, it created a blocking situation which essentially impacted all users across all servers. The product company recommended that I use the standard ASP.NET State service as that was what they technically supported. Why this would make a difference is beyond me -- but I had no choice but to try it! I have attempted to create multiple application pools, adding additional servers, chaning TCP/IP timeout from 20 to 30 seconds, and even calling Microsoft ASP.NET product support, with very little success. I even recommended that they review whether they are using read-only session state instead of read/write per page request -- as I understand that this basically causes every page to make round-trips to state server even if state isn't being used on the page. Unfortunately, the application is developed by our product company and they insist that it is something with my environment because other clients do not have these sort of issues. However, I've talked to other clients and they tell me when they've seen issues like they, they've basically had to create another web farm. This issue almost seems like I've simply reached some architectural limit within the application... Microsoft's position on the issue is that the session state needs to be reduced and the returncode being reported back from the state server indicates buffers are full. To better understand the scope of issues (rather than wait for customers to call and complain), I installed ELMAH and configured it to send me e-mails when unhandled exceptions occur. I basically get 500-1000 e-mails during the time period of high activity! If any one has any other ideas I could try or better ways to troubleshoot, I'd appreciate it.

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  • Windows 7 BSOD - ntoskrnl?

    - by Ken Mason
    2 new HP Pavilion notebooks with 7 Home Premium pre-loaded with Norton. My first act was to use the Norton Removal Tool and load ZoneAlarm free and AVG Free. Frequent random BSOD's ever since...I found my way into Debug and have had various reports regarding ntoskrnl, depending on the status of symbols. It's been many years since I played with (DOS 3.x) debug, so this has been a considerable fumble. Excerpts follow and any insights would be greatly appreciated, as I am not a developer: ADDITIONAL_DEBUG_TEXT: Use '!findthebuild' command to search for the target build information. If the build information is available, run '!findthebuild -s ; .reload' to set symbol path and load symbols. MODULE_NAME: nt FAULTING_MODULE: fffff8000305d000 nt DEBUG_FLR_IMAGE_TIMESTAMP: 4b88cfeb BUGCHECK_STR: 0x7f_8 CUSTOMER_CRASH_COUNT: 1 DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT CURRENT_IRQL: 0 LAST_CONTROL_TRANSFER: from fffff800030ccb69 to fffff800030cd600 STACK_TEXT: fffff80004d6fd28 fffff800030ccb69 : 000000000000007f 0000000000000008 0000000080050033 00000000000006f8 : nt+0x70600 fffff80004d6fd30 000000000000007f : 0000000000000008 0000000080050033 00000000000006f8 fffff80003095e58 : nt+0x6fb69 fffff80004d6fd38 0000000000000008 : 0000000080050033 00000000000006f8 fffff80003095e58 0000000000000000 : 0x7f fffff80004d6fd40 0000000080050033 : 00000000000006f8 fffff80003095e58 0000000000000000 0000000000000000 : 0x8 fffff80004d6fd48 00000000000006f8 : fffff80003095e58 0000000000000000 0000000000000000 0000000000000000 : 0x80050033 fffff80004d6fd50 fffff80003095e58 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : 0x6f8 fffff80004d6fd58 0000000000000000 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt+0x38e58 STACK_COMMAND: kb FOLLOWUP_IP: nt+70600 fffff800`030cd600 48894c2408 mov qword ptr [rsp+8],rcx SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: nt+70600 FOLLOWUP_NAME: MachineOwner IMAGE_NAME: ntoskrnl.exe BUCKET_ID: WRONG_SYMBOLS Followup: MachineOwner ...................................................................... 0: kd !lmi nt Loaded Module Info: [nt] Module: ntkrnlmp Base Address: fffff8000305d000 Image Name: ntkrnlmp.exe Machine Type: 34404 (X64) Time Stamp: 4b88cfeb Sat Feb 27 00:55:23 2010 Size: 5dc000 CheckSum: 545094 Characteristics: 22 perf Debug Data Dirs: Type Size VA Pointer CODEVIEW 25, 19c65c, 19bc5c RSDS - GUID: {7E9A3CAB-6268-45DE-8E10-816E3080A3B7} Age: 2, Pdb: ntkrnlmp.pdb CLSID 4, 19c658, 19bc58 [Data not mapped] Image Type: FILE - Image read successfully from debugger. ntkrnlmp.exe Symbol Type: PDB - Symbols loaded successfully from symbol server. d:\debugsymbols\ntkrnlmp.pdb\7E9A3CAB626845DE8E10816E3080A3B72\ntkrnlmp.pdb Load Report: public symbols , not source indexed d:\debugsymbols\ntkrnlmp.pdb\7E9A3CAB626845DE8E10816E3080A3B72\ntkrnlmp.pdb 0: kd !analyze -v * Bugcheck Analysis * * UNEXPECTED_KERNEL_MODE_TRAP (7f) This means a trap occurred in kernel mode, and it's a trap of a kind that the kernel isn't allowed to have/catch (bound trap) or that is always instant death (double fault). The first number in the bugcheck params is the number of the trap (8 = double fault, etc) Consult an Intel x86 family manual to learn more about what these traps are. Here is a portion of those codes: If kv shows a taskGate use .tss on the part before the colon, then kv. Else if kv shows a trapframe use .trap on that value Else .trap on the appropriate frame will show where the trap was taken (on x86, this will be the ebp that goes with the procedure KiTrap) Endif kb will then show the corrected stack. Arguments: Arg1: 0000000000000008, EXCEPTION_DOUBLE_FAULT Arg2: 0000000080050033 Arg3: 00000000000006f8 Arg4: fffff80003095e58 Debugging Details: BUGCHECK_STR: 0x7f_8 CUSTOMER_CRASH_COUNT: 1 DEFAULT_BUCKET_ID: VISTA_DRIVER_FAULT PROCESS_NAME: System CURRENT_IRQL: 2 LAST_CONTROL_TRANSFER: from fffff800030ccb69 to fffff800030cd600 STACK_TEXT: fffff80004d6fd28 fffff800030ccb69 : 000000000000007f 0000000000000008 0000000080050033 00000000000006f8 : nt!KeBugCheckEx fffff80004d6fd30 fffff800030cb032 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiBugCheckDispatch+0x69 fffff80004d6fe70 fffff80003095e58 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!KiDoubleFaultAbort+0xb2 fffff880089efc60 0000000000000000 : 0000000000000000 0000000000000000 0000000000000000 0000000000000000 : nt!SeAccessCheckFromState+0x58 STACK_COMMAND: kb FOLLOWUP_IP: nt!KiDoubleFaultAbort+b2 fffff800`030cb032 90 nop SYMBOL_STACK_INDEX: 2 SYMBOL_NAME: nt!KiDoubleFaultAbort+b2 FOLLOWUP_NAME: MachineOwner MODULE_NAME: nt IMAGE_NAME: ntkrnlmp.exe DEBUG_FLR_IMAGE_TIMESTAMP: 4b88cfeb FAILURE_BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b2 BUCKET_ID: X64_0x7f_8_nt!KiDoubleFaultAbort+b2 Followup: MachineOwner I tried running Rootkit Revealer but I don't think it works on x64 systems. Similarly Blacklight seems to have aged off. I'm running Sophos Anti-Rootkit now. So far so good...

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  • Why the server is not responding?

    - by par
    Hello! Our server occasionally refuses to serve a simple HTML page. This is happening during a relatively high number of requests. However, the processor is not heavy loaded and there are a lot of free memory. The error seems to occure 1 out of 50 requests in average, depending on the server load. I need to find the source of the problem and take the appropriate actions to eliminate it. I have a suspicion that the problem source is a huge number of incoming network packets. There are 5000 packets per second on average. Traffic - 2 MBits/sec Can this be the cause of the error? There is an interesting thing, in case the server fails to respond, the request string is not logged to access.log by Apache. The error is repeatable from several client computers. DNS is not involved, since I have accessed the server by the IP. I have profiled the problem case with tcpdump utility. These are the good and bad sessions traced by tcpdump. The request is the same in both experiments. Good - server returns response. Bad - no response, time-out error. ---- Bad ---- 12:23:36.366292 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:23:39.362394 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:23:45.365567 IP 123.45.67.890.61749 > myserver.superbservers.com.www: S 2125316338:2125316338(0) win 8192 <mss 1460,nop,nop,sackOK> -------- ---- Good ---- 12:27:07.632229 IP 123.45.67.890.63914 > myserver.superbservers.com.www: S 3581365570:3581365570(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:27:10.620946 IP 123.45.67.890.63914 > myserver.superbservers.com.www: S 3581365570:3581365570(0) win 8192 <mss 1460,nop,wscale 2,nop,nop,sackOK> 12:27:10.620969 IP myserver.superbservers.com.www > 123.45.67.890.63914: S 2654770980:2654770980(0) ack 3581365571 win 5840 <mss 1460,nop,nop,sackOK,nop,wscale 6> 12:27:10.838747 IP 123.45.67.890.63914 > myserver.superbservers.com.www: . ack 1 win 4380 12:27:10.957143 IP 123.45.67.890.63914 > myserver.superbservers.com.www: P 1:213(212) ack 1 win 4380 12:27:10.957152 IP myserver.superbservers.com.www > 123.45.67.890.63914: . ack 213 win 108 12:27:10.965543 IP myserver.superbservers.com.www > 123.45.67.890.63914: P 1:630(629) ack 213 win 108 12:27:10.965621 IP myserver.superbservers.com.www > 123.45.67.890.63914: F 630:630(0) ack 213 win 108 12:27:11.183540 IP 123.45.67.890.63914 > myserver.superbservers.com.www: . ack 631 win 4222 12:27:11.185657 IP 123.45.67.890.63914 > myserver.superbservers.com.www: F 213:213(0) ack 631 win 4222 12:27:11.185663 IP myserver.superbservers.com.www > 123.45.67.890.63914: . ack 214 win 108 -------- Hoster: SuperbHosting OS: Ubuntu Server parameters: E6300 CONROE 1.86GHZ 2 X 1MB CACHE 1066 1GB DDR2 667MHZ This is a link to apache configuration file we use http://repkin5.snow.prohosting.com/apache.txt This is server-status report taken right after time-out error. http://repkin5.snow.prohosting.com/server-status.htm There are only 10 Child Servers running out of 120, so enough space for new requests. VMSTAT procs -----------memory---------- ---swap-- -----io---- -system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 8900 725900 8468 65684 0 0 5 18 11 33 4 3 92 1

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  • How to diagnose computer lockup/freezing problem

    - by Scott Mitchell
    I built a desktop computer a couple years back with the following specs: CPU: Intel Core 2 Quad Q9300 Yorkfield 2.5GHz 6MB L2 Cache LGA 775 95W Quad-Core Processor BX80580Q9300 Motherboard: EVGA 122-CK-NF68-T1 LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard Video Card: Two EVGA 256-P2-N758-TR GeForce 8600GT SCC 256MB 128-bit GDDR3 PCI Express x16 SLI Supported Video Card PSU: SeaSonic S12 Energy Plus SS-550HT 550W ATX12V V2.3 / EPS12V V2.91 SLI Certified CrossFire Ready 80 PLUS Certified Active PFC Power Supply Memory: Two G.SKILL 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL5D-4GBPQ Since its inception, the machine has periodically locked up, the regularlity having varied over the years from once a day to once a month. Typically, lockups happen once every few days. By "lockup" I mean my computer just freezes. The screen locks up, I can't move the mouse. Hitting keys on my keyboard that normally turn LEDs on or off on the keyboard (such as Caps Lock) no longer turn the LEDs on or off. If there was music playing at the time of the lockup, noise keeps coming out of the speakers, but it's just the current frequency/note that plays indefinitely. There is no BSOD. When such a lockup occurs I have to do a hard reboot by either turning off the computer or hitting the reset button. I have the most recent version of the NVIDIA hardware drivers, and update them semi-regularly, but that hasn't seemed to help. I am currently using Windows 7 x64, but was previously using Windows Server 2003 x64 and having the same lockup issues. My guess is that it's somehow video driver or motherboard related, but I don't know how to go about diagnosing this problem to narrow down which of the two is the culprit. Additional information re: cooling Regarding cooling... I've not installed any after-market cooling systems aside from two regular fans I scavenged from an older computer. The fan atop the CPU is the one that shipped with it. One of the two scavenged fans I added it located at the bottom tower of the corner, in an attempt to create some airflow from front to back. The second fan is pointed directly at the two video cards. SpeedFan installation and readings Per studiohack's suggestion, I installed SpeedFan, which provided the following temperature readings: GPU: 63C GPU: 65C System: 76C CPU: 64C AUX: 36C Core 0: 78C Core 1: 76C Core 2: 79C Core 3: 79C Update #3: Another Lockup :-( Well, I had another lockup last night. :-( SpeedFan reported the CPU temp at 38 C when it happened, and there was no spike in temperature leading up to the freeze. One thing I notice is that the freeze seems more likely to happen if I am watching a video. In fact, of the last 5 freezes over the past month, 4 of them have been while watching a video on Flickr. Not necessarily the same video, but a video nevertheless. I don't know if this is just coincidence or if it means anything. (As an aside, each night before bedtime my 2 year old daughter sits on my lap and watches some home videos on Flickr and, in the last month, has learned the phrase, "Uh oh, computer broke.") Update #4: MemTest86 and 3DMark06 Test Results: Per suggestions in the comments, I ran the MemTest86 overnight and it cycled through the 8 GB of memory 5 times without error. I also ran the 3DMark06 test without a problem (see my scores at http://3dmark.com/3dm06/15163549). So... what now? :-) Any further suggestions on what to check? Is there some way to get a stack trace or something when the computer locks like that? Thanks

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  • How to transfer data between two networks efficiently

    - by Tono Nam
    I would like to transfer files between two places over the internet. Right now I have a VPN and I am able to browse, download and transfer files. So my question is not really how to transfer the files; Instead, I would like to use the most efficient approach because the two places constantly share a lot of data. The reason why I want to get rid of the VPN is because it is two slow. Having high upload speed is very expensive/impossible in residential places so I would like to use a different approach. I was thinking about using programs such as http://www.dropbox.com . The problem with Dropbox is that the free version comes with only 2 GB of storage. I think the deals they offer are OK and I might be willing to pay to get that increase in speed. But I am concerned with the speed of transferring data. Dropbox will upload the file to their server then send it from the server to the other location. I would like it to be even faster. Anyway I was thinking why not create a program myself. This is the algorithm that I was thinking of. Let me know if it sounds too crazy. (Remember my goal is to transfer files as fast as possible) Things that I will use in this algorithm: Server on the internet called S (Has fast download and upload speed. I pay to host a website and some services in there. I want to take advantage of it.) Client A at location 1 Client B at location 2 So lets say at location 1, 20 large files are created and need to be transferred to location 2. Client A compresses the files with the highest compression ratio possible. Client A starts sending data via UDP to client B. Because I am using UDP I will include the sequence number on each packet. Have server S help speed up things. For example every time a packet is lost we can use Server S to inform client A that it needs to resend a packet. Anyways I think this approach will increase the transfer rate. I do not know if it is possible to start sending data while it is being compressed. Or if it is possible to start decompressing data even if we are not done receiving the whole file. Maybe it will be faster to start sending the files right away without compressing. If I knew that I will always be sending large text files then I will obviously use the compression. I need this as a general algorithm. So I guess my question is could I increase performance by using UDP instead of TCP and by using an extra server to keep track of lost packets? And how should I compress files before sending? Compressing a 1 GB file with the highest compression ratio takes about 1 hour! I would like to take advantage of that time by sending it as it is being compressed.

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  • Secure method of changing a user's password via Python script/non-interactively

    - by Matthew Rankin
    I've created a Python script using Fabric to configure a freshly built Slicehost Ubuntu slice. In case you're not familiar with Fabric, it uses Paramiko, a Python SSH2 client, to provide remote access "for application deployment or systems administration tasks." One of the first things I have the Fabric script do is to create a new admin user and set their password. Unlike Pexpect, Fabric cannot handle interactive commands on the remote system, so I need to set the user's password non-interactively. At present, I'm using the chpasswd command to change the password. This transmits the password as clear text over SSH to the remote system. Questions Is my current method of setting the password a security concern? Currently, the drawback I see is that Fabric shows the password as clear text on my local system as follows: [xxx.xx.xx.xxx] run: echo "johnsmith:supersecretpassw0rd" | chpasswd. Since I only run the Fabric script from my laptop, I don't think this is a security issue, but I'm interested in others' input. Is there a better method for setting the user's password non-interactively? Another option, would be to use Pexpect from within the Fabric script to set the password. Current Code # Fabric imports and host configuration excluded for brevity root_password = getpass.getpass("Root's password given by SliceManager: ") admin_username = prompt("Enter a username for the admin user to create: ") admin_password = getpass.getpass("Enter a password for the admin user: ") env.user = 'root' env.password = root_password # Create the admin group and add it to the sudoers file admin_group = 'admin' run('addgroup {group}'.format(group=admin_group)) run('echo "%{group} ALL=(ALL) ALL" >> /etc/sudoers'.format( group=admin_group) ) # Create the new admin user (default group=username); add to admin group run('adduser {username} --disabled-password --gecos ""'.format( username=admin_username) ) run('adduser {username} {group}'.format( username=admin_username, group=admin_group) ) # Set the password for the new admin user run('echo "{username}:{password}" | chpasswd'.format( username=admin_username, password=admin_password) ) Local System Terminal I/O $ fab config_rebuilt_slice Root's password given by SliceManager: Enter a username for the admin user to create: johnsmith Enter a password for the admin user: [xxx.xx.xx.xxx] run: addgroup admin [xxx.xx.xx.xxx] out: Adding group `admin' (GID 1000) ... [xxx.xx.xx.xxx] out: Done. [xxx.xx.xx.xxx] run: echo "%admin ALL=(ALL) ALL" >> /etc/sudoers [xxx.xx.xx.xxx] run: adduser johnsmith --disabled-password --gecos "" [xxx.xx.xx.xxx] out: Adding user `johnsmith' ... [xxx.xx.xx.xxx] out: Adding new group `johnsmith' (1001) ... [xxx.xx.xx.xxx] out: Adding new user `johnsmith' (1000) with group `johnsmith' ... [xxx.xx.xx.xxx] out: Creating home directory `/home/johnsmith' ... [xxx.xx.xx.xxx] out: Copying files from `/etc/skel' ... [xxx.xx.xx.xxx] run: adduser johnsmith admin [xxx.xx.xx.xxx] out: Adding user `johnsmith' to group `admin' ... [xxx.xx.xx.xxx] out: Adding user johnsmith to group admin [xxx.xx.xx.xxx] out: Done. [xxx.xx.xx.xxx] run: echo "johnsmith:supersecretpassw0rd" | chpasswd [xxx.xx.xx.xxx] run: passwd --lock root [xxx.xx.xx.xxx] out: passwd: password expiry information changed. Done. Disconnecting from [email protected]... done.

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  • UFW as an active service on Ubuntu

    - by lamcro
    Every time I restart my computer, and check the status of the UFW firewall (sudo ufw status), it is disabled, even if I then enable and restart it. I tried putting sudo ufw enable as one of the startup applications but it asks for the sudo password every time I log on, and I'm guessing it does not protect anyone else who logs on my computer. How can I setup ufw so it is activated when I turn on my computer, and protects all accounts? Update I just tried /etc/init.d/ufw start, and it activated the firewall. Then I restarted the computer, and again it was disabled. content of /etc/ufw/ufw.conf # /etc/ufw/ufw.conf # # set to yes to start on boot ENABLED=yes # set to one of 'off', 'low', 'medium', 'high' LOGLEVEL=full content of /etc/default/ufw # /etc/default/ufw # # Set to yes to apply rules to support IPv6 (no means only IPv6 on loopback # accepted). You will need to 'disable' and then 'enable' the firewall for # the changes to take affect. IPV6=no # Set the default input policy to ACCEPT, ACCEPT_NO_TRACK, DROP, or REJECT. # ACCEPT enables connection tracking for NEW inbound packets on the INPUT # chain, whereas ACCEPT_NO_TRACK does not use connection tracking. Please note # that if you change this you will most likely want to adjust your rules. DEFAULT_INPUT_POLICY="DROP" # Set the default output policy to ACCEPT, ACCEPT_NO_TRACK, DROP, or REJECT. # ACCEPT enables connection tracking for NEW outbound packets on the OUTPUT # chain, whereas ACCEPT_NO_TRACK does not use connection tracking. Please note # that if you change this you will most likely want to adjust your rules. DEFAULT_OUTPUT_POLICY="ACCEPT" # Set the default forward policy to ACCEPT, DROP or REJECT. Please note that # if you change this you will most likely want to adjust your rules DEFAULT_FORWARD_POLICY="DROP" # Set the default application policy to ACCEPT, DROP, REJECT or SKIP. Please # note that setting this to ACCEPT may be a security risk. See 'man ufw' for # details DEFAULT_APPLICATION_POLICY="SKIP" # By default, ufw only touches its own chains. Set this to 'yes' to have ufw # manage the built-in chains too. Warning: setting this to 'yes' will break # non-ufw managed firewall rules MANAGE_BUILTINS=no # # IPT backend # # only enable if using iptables backend IPT_SYSCTL=/etc/ufw/sysctl.conf # extra connection tracking modules to load IPT_MODULES="nf_conntrack_ftp nf_nat_ftp nf_conntrack_irc nf_nat_irc" Update Followed your advise and ran update-rc.d with no luck. lester@mcgrath-pc:~$ sudo update-rc.d ufw defaults update-rc.d: warning: /etc/init.d/ufw missing LSB information update-rc.d: see <http://wiki.debian.org/LSBInitScripts> Adding system startup for /etc/init.d/ufw ... /etc/rc0.d/K20ufw -> ../init.d/ufw /etc/rc1.d/K20ufw -> ../init.d/ufw /etc/rc6.d/K20ufw -> ../init.d/ufw /etc/rc2.d/S20ufw -> ../init.d/ufw /etc/rc3.d/S20ufw -> ../init.d/ufw /etc/rc4.d/S20ufw -> ../init.d/ufw /etc/rc5.d/S20ufw -> ../init.d/ufw lester@mcgrath-pc:~$ ls -l /etc/rc?.d/*ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc0.d/K20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc1.d/K20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc2.d/S20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc3.d/S20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc4.d/S20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc5.d/S20ufw -> ../init.d/ufw lrwxrwxrwx 1 root root 13 2009-12-20 20:34 /etc/rc6.d/K20ufw -> ../init.d/ufw

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  • wireless internet in linux is very very slow... but in windows.... everythnings fine

    - by Cody Acer
    yesterday when i was connecting to our neighbors wifi connection which is the signal strength is below 50%, i cant browse anything... even ping to gateway. 100% packet loss, and sometimes.. i can connect awesomely i can open my facebook account for 15 minutes but after 15min.. connection is extremely slow. but not windows i can surf even the signal str is very poor weird ey??.. root@Emely:~# lspci -knn 00:00.0 Host bridge [0600]: Intel Corporation Atom Processor D4xx/D5xx/N4xx/N5xx DMI Bridge [8086:a010] Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: agpgart-intel 00:02.0 VGA compatible controller [0300]: Intel Corporation Atom Processor D4xx/D5xx/N4xx/N5xx Integrated Graphics Controller [8086:a011] Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: i915 Kernel modules: i915 00:02.1 Display controller [0380]: Intel Corporation Atom Processor D4xx/D5xx/N4xx/N5xx Integrated Graphics Controller [8086:a012] Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] 00:1b.0 Audio device [0403]: Intel Corporation NM10/ICH7 Family High Definition Audio Controller [8086:27d8] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: snd_hda_intel Kernel modules: snd-hda-intel 00:1c.0 PCI bridge [0604]: Intel Corporation NM10/ICH7 Family PCI Express Port 1 [8086:27d0] (rev 02) Kernel driver in use: pcieport Kernel modules: shpchp 00:1c.1 PCI bridge [0604]: Intel Corporation NM10/ICH7 Family PCI Express Port 2 [8086:27d2] (rev 02) Kernel driver in use: pcieport Kernel modules: shpchp 00:1c.2 PCI bridge [0604]: Intel Corporation NM10/ICH7 Family PCI Express Port 3 [8086:27d4] (rev 02) Kernel driver in use: pcieport Kernel modules: shpchp 00:1c.3 PCI bridge [0604]: Intel Corporation NM10/ICH7 Family PCI Express Port 4 [8086:27d6] (rev 02) Kernel driver in use: pcieport Kernel modules: shpchp 00:1d.0 USB controller [0c03]: Intel Corporation NM10/ICH7 Family USB UHCI Controller #1 [8086:27c8] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: uhci_hcd 00:1d.1 USB controller [0c03]: Intel Corporation NM10/ICH7 Family USB UHCI Controller #2 [8086:27c9] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: uhci_hcd 00:1d.2 USB controller [0c03]: Intel Corporation NM10/ICH7 Family USB UHCI Controller #3 [8086:27ca] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: uhci_hcd 00:1d.3 USB controller [0c03]: Intel Corporation NM10/ICH7 Family USB UHCI Controller #4 [8086:27cb] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: uhci_hcd 00:1d.7 USB controller [0c03]: Intel Corporation NM10/ICH7 Family USB2 EHCI Controller [8086:27cc] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: ehci-pci 00:1e.0 PCI bridge [0604]: Intel Corporation 82801 Mobile PCI Bridge [8086:2448] (rev e2) 00:1f.0 ISA bridge [0601]: Intel Corporation NM10 Family LPC Controller [8086:27bc] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: lpc_ich Kernel modules: lpc_ich 00:1f.2 SATA controller [0106]: Intel Corporation NM10/ICH7 Family SATA Controller [AHCI mode] [8086:27c1] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: ahci Kernel modules: ahci 00:1f.3 SMBus [0c05]: Intel Corporation NM10/ICH7 Family SMBus Controller [8086:27da] (rev 02) Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel modules: i2c-i801 05:00.0 Network controller [0280]: Broadcom Corporation BCM4313 802.11bgn Wireless Network Adapter [14e4:4727] (rev 01) Subsystem: Wistron NeWeb Corp. Device [185f:051a] Kernel driver in use: bcma-pci-bridge Kernel modules: bcma 09:00.0 Ethernet controller [0200]: Marvell Technology Group Ltd. 88E8040 PCI-E Fast Ethernet Controller [11ab:4354] Subsystem: Samsung Electronics Co Ltd Notebook N150P [144d:c072] Kernel driver in use: sky2 Kernel modules: sky2 root@Emely:~# ip addr show 1: lo: mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 inet 127.0.0.1/8 scope host lo inet6 ::1/128 scope host valid_lft forever preferred_lft forever 2: eth0: mtu 1500 qdisc pfifo_fast state DOWN qlen 1000 link/ether e8:11:32:2e:a6:fd brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:1b:b1:a9:ac:e0 brd ff:ff:ff:ff:ff:ff inet 192.168.1.108/24 brd 192.168.1.255 scope global wlan0 inet6 fe80::21b:b1ff:fea9:ace0/64 scope link valid_lft forever preferred_lft forever root@Emely:~# ip link show 1: lo: mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00 2: eth0: mtu 1500 qdisc pfifo_fast state DOWN qlen 1000 link/ether e8:11:32:2e:a6:fd brd ff:ff:ff:ff:ff:ff 3: wlan0: mtu 1500 qdisc mq state UP qlen 1000 link/ether 00:1b:b1:a9:ac:e0 brd ff:ff:ff:ff:ff:ff root@Emely:~# rfkill list all 0: samsung-wlan: Wireless LAN Soft blocked: no Hard blocked: no 1: samsung-bluetooth: Bluetooth Soft blocked: no Hard blocked: no 2: hci0: Bluetooth Soft blocked: no Hard blocked: no 3: phy0: Wireless LAN Soft blocked: no Hard blocked: no is this a wireless driver issue?

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  • How to transfer data between two netowks efficiently

    - by Tono Nam
    I will like to transfer files between two places over the internet. Right now I have a VPN and I am able to browse, download and transfer files. So my question is not really how to transfer the files; Instead, I will like to use the most efficient approach because the two places constantly share a lot of data. The reason why I want to get rid of the vpn is because it is two slow. Having high upload speed is very expensive/impossible on residential places so I will like to use a different approach. I was thinking about using programs such as http://www.dropbox.com . The problem with dropbox is it only enables 2 GB of storage in order for it to be free. I think the deals they offer are ok and I might be willing to pay to get that increase in speed. But I am concerned with the speed of transferring data. Dropbox will upload the file to their server then send it from the server to the other location. I will like it even faster lol. Anyways I was thinking why not create a program my self. This is the algorithm that I was thinking let me know if it sounds to crazy. (remember my goal is to transfer files as fastest as possible) Things that I will use in this algorithm: Server on the internet called S ( has fast download and upload speed. I pay to host a website and some services in there. I want to take advantage of it) Client A on location 1 Client B on location 2 So lets say on location 1 20 large files are created and need to be transferred to location 2. Client A compresses the files with the highest compression ratio possible. Client A starts sending data via UDP to client B. Because I am using UDP I will include the sequence number on each package. Have server S help speed up things. For example every time a package is lost we can use Server S to inform client A that it needs to resend a package. Anyways I think this approach will increase the transfer rate. I do not know if it is possible to start sending data meanwhile it is being compressed. Also if it is possible to start decompressing data even if we are not done receiving all the info. Maybe it will be faster to start sending the files right away without compressing. If I knew that I will always be sending large text files then I will obviously use the compression. I need this as a general algorithm. So i guess my question is should using UDP over TCP could increase performance by using an extra server to keep track of lost packages? and How should I compress files before sending? compressing a 1 GB file with the highest compression ration takes about 1 hour! I will like to take advantage of that time by sending it meanwhile it is compressed.

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  • virturalmin webmin dose not respond

    - by Miranda
    I have installed Virtualmin on a CentOS remote server, but it dose not seem to work https://115.146.95.118:10000/ at least the Webmin page dose not work. I have opened those ports http ALLOW 80:80 from 0.0.0.0/0 ALLOW 443:443 from 0.0.0.0/0 ssh ALLOW 22:22 from 0.0.0.0/0 virtualmin ALLOW 20000:20000 from 0.0.0.0/0 ALLOW 10000:10009 from 0.0.0.0/0 And restarting Webmin dose not solve it: /etc/rc.d/init.d/webmin restart Stopping Webmin server in /usr/libexec/webmin Starting Webmin server in /usr/libexec/webmin And I have tried to use Amazon EC2 this time, still couldn't get it to work. http://ec2-67-202-21-21.compute-1.amazonaws.com:10000/ [ec2-user@ip-10-118-239-13 ~]$ netstat -an | grep :10000 tcp 0 0 0.0.0.0:10000 0.0.0.0:* LISTEN udp 0 0 0.0.0.0:10000 0.0.0.0:* [ec2-user@ip-10-118-239-13 ~]$ sudo iptables -L -n Chain INPUT (policy ACCEPT) target prot opt source destination ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:20 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:21 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:53 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:20000 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:10000 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:443 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:993 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:143 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:995 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:110 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:20 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:21 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:53 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:587 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:25 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 Chain FORWARD (policy ACCEPT) target prot opt source destination Chain OUTPUT (policy ACCEPT) target prot opt source destination Since I need more than 10 reputation to post image, you can find the screenshots of the security group setting at the Webmin Support Forum. I have tried: sudo iptables -A INPUT -p tcp -m tcp --dport 10000 -j ACCEPT It did not change anything. [ec2-user@ip-10-118-239-13 ~]$ sudo yum install openssl perl-Net-SSLeay perl-Crypt-SSLeay Loaded plugins: fastestmirror, priorities, security, update-motd Loading mirror speeds from cached hostfile * amzn-main: packages.us-east-1.amazonaws.com * amzn-updates: packages.us-east-1.amazonaws.com amzn-main | 2.1 kB 00:00 amzn-updates | 2.3 kB 00:00 Setting up Install Process Package openssl-1.0.0j-1.43.amzn1.i686 already installed and latest version Package perl-Net-SSLeay-1.35-9.4.amzn1.i686 already installed and latest version Package perl-Crypt-SSLeay-0.57-16.4.amzn1.i686 already installed and latest version Nothing to do [ec2-user@ip-10-118-239-13 ~]$ nano /etc/webmin/miniserv.conf GNU nano 2.0.9 File: /etc/webmin/miniserv.conf port=10000 root=/usr/libexec/webmin mimetypes=/usr/libexec/webmin/mime.types addtype_cgi=internal/cgi realm=Webmin Server logfile=/var/webmin/miniserv.log errorlog=/var/webmin/miniserv.error pidfile=/var/webmin/miniserv.pid logtime=168 ppath= ssl=1 env_WEBMIN_CONFIG=/etc/webmin env_WEBMIN_VAR=/var/webmin atboot=1 logout=/etc/webmin/logout-flag listen=10000 denyfile=\.pl$ log=1 blockhost_failures=5 blockhost_time=60 syslog=1 session=1 server=MiniServ/1.585 userfile=/etc/webmin/miniserv.users keyfile=/etc/webmin/miniserv.pem passwd_file=/etc/shadow passwd_uindex=0 passwd_pindex=1 passwd_cindex=2 passwd_mindex=4 passwd_mode=0 preroot=virtual-server-theme passdelay=1 sessiononly=/virtual-server/remote.cgi preload= mobile_preroot=virtual-server-mobile mobile_prefixes=m. mobile. anonymous=/virtualmin-mailman/unauthenticated=anonymous ssl_cipher_list=ECDHE-RSA-AES256-SHA384:AES256-SHA256:AES256-SHA256:RC4:HIGH:MEDIUM:+TLSv1:!MD5:!SSLv2:+SSLv3:!ADH:!aNULL:!eNULL:!NULL:!DH:!ADH:!EDH:!AESGCM

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  • Intermittent 404 on select assets, LAMP stack

    - by Tom Lagier
    We have a LAMP stack WordPress server that is serving most assets correctly. However, one plugin's CSS file and several images are returning soft 404s roughly 20% of the time. I can't find any reference to the 404 in the access logs, but the browser is definitely receiving a 404 response from somewhere (WordPress, I would assume). When I use an alias URL that does not match the site URL but does resolve to the asset path, the resource loads correctly 100% of the time. However, using the site url only resolves for the select, problematic assets 20% of the time. You can test one of the problematic assets here: http://www.mreco.org/wp-content/uploads/2014/05/zero-cost.jpg However the alias link always resolves correctly: http://mr-eco.wordpress.promocampaigns.com/wp-content/uploads/2014/05/zero-cost.jpg Stranger, if I attempt to access outdated content that definitely does not exist on the server, at the live URL it returns the content roughly 50% of the time. Using the alias link, it 404s 100% of the time - the correct behavior. Error log and PHP error log are clean. A sample access log (pulled from grep 'zero-cost.jpg' /var/log/httpd/mr-eco-access_log) from several refreshes of the live direct link (where I am not seeing any 404's): 10.166.202.202 - - [28/May/2014:20:27:41 +0000] "GET /wp-content/uploads/2014/05/zero-cost.jpg HTTP/1.1" 304 - 10.166.202.202 - - [28/May/2014:20:27:42 +0000] "GET /wp-content/uploads/2014/05/zero-cost.jpg HTTP/1.1" 304 - 10.166.202.202 - - [28/May/2014:20:27:43 +0000] "GET /wp-content/uploads/2014/05/zero-cost.jpg HTTP/1.1" 304 - 10.166.202.202 - - [28/May/2014:20:27:43 +0000] "GET /wp-content/uploads/2014/05/zero-cost.jpg HTTP/1.1" 304 - 10.176.201.37 - - [28/May/2014:20:27:56 +0000] "GET /wp-content/uploads/2014/05/zero-cost.jpg HTTP/1.1" 200 57027 Chrome's dev tools list the following network activity before displaying 404 page content: zero-cost.jpg /wp-content/uploads/2014/05 GET 404 Not Found text/html Other 15.9?KB 73.2?KB 953?ms 947?ms My Apache configuration is standard, I've listed the virtual host entry and .htaccess file below. I can provide other parts of Apache config if necessary. Virtual host: <VirtualHost *:80> DocumentRoot /var/www/public_html/mr-eco.wordpress.promocampaigns.com ServerName www.mreco.org ServerAlias mreco.org mr-eco.wordpress.promocampaigns.com ErrorLog logs/mr-eco-error_log CustomLog logs/mr-eco-access_log common <Directory /var/www/public_html/mr-eco.wordpress.promocampaigns.com> AllowOverride All SetOutputFilter DEFLATE </Directory> </VirtualHost> .htaccess: # BEGIN WordPress <IfModule mod_rewrite.c> RewriteEngine On RewriteBase / RewriteRule ^index\.php$ - [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L] </IfModule> # END WordPress I have checked for multiple A records and can confirm that there is a single A record pointing at the domain: ;; ANSWER SECTION: mreco.org. 60 IN A 50.18.58.174 I'm fairly new to systems administration, and at a complete loss as to what could cause this. In the past, inconsistently 404ing assets have been because of out-of-sync instances behind a load balancer. In this case, it is a single instance behind the load balancer. Because of the inconsistency, it feels like a caching issue. We don't make use of Apache caching, and as far as I know WordPress should not be caching either. What I've done so far: Reset WordPress permalinks Disabled WordPress plugins Re-generated WordPress .htaccess file Swapped ServerName and ServerAlias directives Cleared browser cache Confirmed disk location of resources Checked PHP, access, and error logs Confirmed correct DNS setup (can post if necessary) I'm at a total loss. Thanks for helping me out!

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  • Linux not buffering block I/O when the device is not "in use" (i.e. mounted)

    - by Radek Hladík
    I am installing new server and I've found an interesting issue. The server is running Fedora 19 (3.11.7-200.fc19.x86_64 kernel) and is supposed to host a few KVM/Qemu virtual servers (mail server, file server, etc..). The HW is Intel(R) Xeon(R) CPU 5160 @ 3.00GHz with 16GB RAM. One of the most important features will be Samba server and we have decided to make it as virtual machine with almost direct access to the disks. So the real HDD is cached on SSD (via bcache) then raided with md and the final device is exported into the virtual machine via virtio. The virtual machine is again Fedora 19 with the same kernel. One important topic to find out is whether the virtualization layer will not introduce high overload into disk I/Os. So far I've been able to get up to 180MB/s in VM and up to 220MB/s on real HW (on the SSD disk). I am still not sure why the overhead is so big but it is more than the network can handle so I do not care so much. The interesting thing is that I've found that the disk reads are not buffered in the VM unless I create and mount FS on the disk or I use the disks somehow. Simply put: Lets do dd to read disk for the first time (the /dev/vdd is an old Raptor disk 70MB/s is its real speed): [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 36.8038 s, 71.2 MB/s Buffers: 14444 kB Rereading the data shows that they are cached somewhere but not in buffers of the VM. Also the speed increased to "only" 500MB/s. The VM has 4GB of RAM (more that the test file) [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.16016 s, 508 MB/s Buffers: 14444 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.05727 s, 518 MB/s Buffers: 14444 kB Now lets mount the FS on /dev/vdd and try the dd again: [root@localhost ~]# mount /dev/vdd /mnt/tmp [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 4.68578 s, 559 MB/s Buffers: 2574592 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 1.50504 s, 1.7 GB/s Buffers: 2574592 kB While the first read was the same, all 2.6GB got buffered and the next read was at 1.7GB/s. And when I unmount the device: [root@localhost ~]# umount /mnt/tmp [root@localhost ~]# cat /proc/meminfo | grep Buffers Buffers: 14452 kB [root@localhost ~]# dd if=/dev/vdd of=/dev/null bs=256k count=10000 ; cat /proc/meminfo | grep Buffers 2621440000 bytes (2.6 GB) copied, 5.10499 s, 514 MB/s Buffers: 14468 kB The bcache was disabled while testing and the results are same on faster (newer) HDDs and on SSD (except for the initial read speed of course). To sum it up. When I read from the device via dd first time, it gets read from the disk. Next time I reread it gets cached in the host but not in the guest (thats actually the same issue, more on that later). When I mount the filesystem but try to read the device directly it gets cached in VM (via buffers). As soon as I stop "using" it, buffers are discarded and the device is not cached anymore in the VM. When I looked into buffers value on the host I realized that the situation is the same. The block I/O gets buffered only when the disk is in use, in this case it means "exported to a VM". On host, after all the measurement done: 3165552 buffers On the host, after the VM shutdown: 119176 buffers I know it is not important as the disks will be mounted all the time but I am curious and I would like to know why it is working like this.

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  • Setting up a minimalist linux environment

    - by Nate
    All right, I've been messing around with various linux distros and a variety of window managers (I seem to change operating systems like most people change their pants), and I've gotten to the point where I know what I want but I'm not sure the best way to set it up. Here's what I want out of my programming machine: I don't want a status bar. I don't want a menu bar. When there are no windows open, the screen should show my desktop background and nothing else. I'll use alt+f2 to run things, and my shell prompt will tell me my battery life and the time. I'll open network controls and volume controls when I need them, no need for them to pollute the screen all the time. I want a good, simple terminal emulator. I'll be using it with tmux. It should have no title bar and, if possible, no app frame. It's ok if I have to run it in full screen mode to remove the app frame, but only if it still plays nicely with alt-tab and workspaces. I want a dirt-simple window manager. It needs to support transparency: I don't have a lot of screen real-estate and I often overlay the terminal on the browser and type out commands. I don't want a tiling-only system, for the above reason. Bonus points for tiling and overlaying. I'd like multiple workspaces. I prefer to have one gui per workspace. If I could 'pin' the terminal emulator to always show up in each workspace, that's bonus points. If not, I can have a terminal emulator in each workspace attached to the same tmux instance. I'd like a way to set up a keypress that always takes me to the current open terminal emulator. Currently, 90% of the time I only have two windows open: the terminal emulator and something else. In this scenario, alt-tab works like a toggle between the two. If I have another gui open (like a developer window with a web browser), this throws a wrench in my workflow. I'd like a way to assign, for example, 'super-T' to switch to the first open terminal emulator. Bonus points if I can also assign 'super-B' (or whatever) to switch to the first open browser. So far I've been messing around with gnome and tweaking it heavily to match my preferences, but that seems like overkill and I can never get it quite right. I've toyed with xmonad, but it's more for handling many windows, and I usually only have the two. and am considering fluxbox, but I was wondering if any of your minimalists out there had suggestions that might better match my workflow. I'm sick of fighting the window manager, I just want it to get out of my way. Edit: To make things clear, I am not considering switching to a mac/windows environment. I find programming in windows to be a bore, and I have no interest in buying new (read: mac) hardware. Thanks! -Nate

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  • Bizarre and very specific Internet connection loss

    - by Synetech
    Yesterday (Friday, September 21, 2012), my Internet connection started acting up. After some testing, I confirmed a very specific and baffling set of symptoms: Internet connection goes away every 25-35 minutes (I did not confirm the exact interval, but it seems to be about 30 mins.) Only some protocols are affected; HTTP*, P2P, etc. stop working; FTP, etc. continue to work When it’s stopped, cannot even ping router or cable-modem IPs or view their firmware pages Domain-names and IPs are irrelevant (for protocols that stop working, neither work, for those that still work, both work) Resetting router fixes it for another 30 minutes Keeping the connection idle or active doesn’t seem to make a difference (nor the bandwidth usage in that period) Connecting directly to cable-modem allows it to work indefinitely Disconnecting the router from the cable-modem works indefinitely (no Internet connection obviously, but can still access router IP and firmware page) Connecting the router to the cable-modem, but putting the modem on standby also works indefinitely Same problem with both a wireless laptop and wired (on any port) desktop (both Windows 7; will try to test Windows XP when possible) Nothing had changed in the days leading up to the issue. No modifications to the networking configuration or the router; there were not even any Windows updates except for an MSSE definition update. Waiting does not fix it, nor does any amount of fiddling with anything; only resetting the router fixes it for 30 minutes (resetting the cable-modem doesn't work either) I tried cleaning the pins in the router’s plugs, but that didn’t help, which was not really a surprise since I was not getting a lost connection error. Obviously my first thought was that the router was having a problem, and this is borne out by some tests. The problem is that when it drops, it is not a full drop since I can still do things like ftp ftp.mcafee.com and such which means that the connection and DNS are still working. Moreover, if it were the router, then why does it stay alive indefinitely when not connected to the cable-modem (i.e., no outside influence)? The problem doesn't seem to be either the cable-modem nor the router, but rather an interaction between the two, like something from the outside (port scan? hacker? ISP?) that is triggering a problem in the router. I see that there have been a couple of vulnerabilities for the DI-524, but those were a while back and should be fixed since I have the last firmware for it. I don’t think it’s my ISP (Rogers) since I have been using the router for several years without problem and can connect indefinitely when bypassing it. But I can’t rule them out since that is one of the only possible things that could have suddenly changed. Does anybody have any ideas of explanations, fixed, or tests? (I note that when I opened the router, I heard a very high-pitched noise from somewhere near the capacitors/ferrite ring which I don’t think I heard the last time I opened it a few years ago, but then if it were that, then why would it affect only a very small, specific set of functions?)

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  • simple and reliable centralized logging inside Amazon VPC

    - by Nakedible
    I need to set up centralized logging for a set of servers (10-20) in an Amazon VPC. The logging should be as to not lose any log messages in case any single server goes offline - or in the case that an entire availability zone goes offline. It should also tolerate packet loss and other normal network conditions without losing or duplicating messages. It should store the messages durably, at the minimum on two different EBS volumes in two availability zones, but S3 is a good place as well. It should also be realtime so that the messages arrive within seconds of their generation to two different availability zones. I also need to sync logfiles not generated via syslog, so a syslog-only centralized logging solution would not fulfill all the needs, although I guess that limitation could be worked around. I have already reviewed a few solutions, and I will list them here: Flume to Flume to S3: I could set up two logservers as Flume hosts which would store log messages either locally or in S3, and configure all the servers with Flume to send all messages to both servers, using the end-to-end reliability options. That way the loss of a single server shouldn't cause lost messages and all messages would arrive in two availability zones in realtime. However, there would need to be some way to join the logs of the two servers, deduplicating all the messages delivered to both. This could be done by adding a unique id on the sending side to each message and then write some manual deduplication runs on the logfiles. I haven't found an easy solution to the duplication problem. Logstash to Logstash to ElasticSearch: I could install Logstash on the servers and have them deliver to a central server via AMQP, with the durability options turned on. However, for this to work I would need to use some of the clustering capable AMQP implementations, or fan out the deliver just as in the Flume case. AMQP seems to be a yet another moving part with several implementations and no real guidance on what works best this sort of setup. And I'm not entirely convinced that I could get actual end-to-end durability from logstash to elasticsearch, assuming crashing servers in between. The fan-out solutions run in to the deduplication problem again. The best solution that would seem to handle all the cases, would be Beetle, which seems to provide high availability and deduplication via a redis store. However, I haven't seen any guidance on how to set this up with Logstash and Redis is one more moving part again for something that shouldn't be terribly difficult. Logstash to ElasticSearch: I could run Logstash on all the servers, have all the filtering and processing rules in the servers themselves and just have them log directly to a removet ElasticSearch server. I think this should bring me reliable logging and I can use the ElasticSearch clustering features to share the database transparently. However, I am not sure if the setup actually survives Logstash restarts and intermittent network problems without duplicating messages in a failover case or similar. But this approach sounds pretty promising. rsync: I could just rsync all the relevant log files to two different servers. The reliability aspect should be perfect here, as the files should be identical to the source files after a sync is done. However, doing an rsync several times per second doesn't sound fun. Also, I need the logs to be untamperable after they have been sent, so the rsyncs would need to be in append-only mode. And log rotations mess things up unless I'm careful. rsyslog with RELP: I could set up rsyslog to send messages to two remote hosts via RELP and have a local queue to store the messages. There is the deduplication problem again, and RELP itself might also duplicate some messages. However, this would only handle the things that log via syslog. None of these solutions seem terribly good, and they have many unknowns still, so I am asking for more information here from people who have set up centralized reliable logging as to what are the best tools to achieve that goal.

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  • What would make a noise in a PC on graphics operations on a passively-cooled system?

    - by T.J. Crowder
    I have this system based on the Intel D510MO motherboard, which is basically an Atom D510 (dual-core HT Atom w/built-in GPU), an Intel NM10 chipset, and a Realtek Gigabit LAN controller. It's entirely passively cooled. I noticed almost immediately that there was a kind of very, very soft noise that corresponded with graphics operations, sort of the noise you'd get if you had a sheet of flat paper and slid something really light across it — but more electronic than that. I wrote it off as observation error and/or disk activity triggered by the graphics operation (although the latter seemed like a lot of unnecessary disk activity). It isn't. I got curious enough that I finally did a few controlled experiments, and here's what I've determined: It isn't the HDD. For one thing, the sounds the HDD makes (when seeking, when reading or writing, when just sitting there spinning) is different. For another, I used sudo hdparm -y /dev/sda (I'm using Ubuntu 10.04 LTS) to temporarily put the disk on standby while making sure that non-disk graphics op was happening in a loop. The disk spun down, but the other sound continued, corresponding perfectly with the timing of the graphics op. (Then the disk spun up again, but it takes long enough that I could rule out the HDD.) It isn't the monitor; I ensured the two were well physically-separated and the sound was definitely coming from the main box. It isn't something else in the room; the sound is coming from the box. It isn't cross-talk to an audio circuit coming out the speakers. (It doesn't have any speakers.) It isn't my mouse (e.g., when I'm trying to make graphics ops happen); the sound happens if I set up a recurring operation and don't use the mouse at all, or if I lift the mouse off the table slightly (but enough that the laser still registers movement). It isn't the voices in my head; they never whisper like that. Other observations: It doesn't seem to matter what the graphics operation is; anything that changes what's on the screen seems to do it. I get the sound when moving the mouse over the Chromium tab bar (which makes the tab backgrounds change); I get it when a web page has a counter on it that changes the text on the page: I get it when dragging window contents around. The sound is very, very slightly louder if the graphics op is larger, like scrolling a text area when writing a question on superuser.com, than for smaller operations like the tick counter on the web page. But it's very slight. It's fairly loud (and of good duration) when the op involves color changes to substantial surface areas. For instance, when asking a question here on superuser and you move the cursor between the question box and the tag box, and the help to the right fades out, changes, and fades back in. (Yet another example related to the web browser, so let me say: I hear it when operations completely unrelated to the web browser as well.) It doesn't sound like arcing or anything like that (I'd've shut off the machine Right Quick Like if it did). Moving windows does it. Scrolling windows (by and large) doesn't. I have the feeling I've heard this sort of thing before, when all system fans were on low and such, with other systems — but (again) written it off as observational error. For all the world it's like I'm hearing the CPU working (as opposed to the GPU; note the window scroll thing above) or data being transferred somewhere, but that just seems...unlikely. So what am I hearing? This may seem like a very localized question, but perhaps other silent PC enthusiasts may be interested as well...

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  • Why do we need different CPU architecture for server & mini/mainframe & mixed-core?

    - by claws
    Hello, I was just wondering what other CPU architectures are available other than INTEL & AMD. So, found List of CPU architectures on Wikipedia. It categorizes notable CPU architectures into following categories. Embedded CPU architectures Microcomputer CPU architectures Workstation/Server CPU architectures Mini/Mainframe CPU architectures Mixed core CPU architectures I was analyzing the purposes and have few doubts. I taking Microcomputer CPU (PC) architecture as reference and comparing others. Embedded CPU architecture: They are a completely new world. Embedded systems are small & do very specific task mostly real time & low power consuming so we do not need so many & such wide registers available in a microcomputer CPU (typical PC). In other words we do need a new small & tiny architecture. Hence new architecture & new instruction RISC. The above point also clarifies why do we need a separate operating system (RTOS). Workstation/Server CPU architectures I don't know what is a workstation. Someone clarify regarding the workstation. As of the server. It is dedicated to run a specific software (server software like httpd, mysql etc.). Even if other processes run we need to give server process priority therefore there is a need for new scheduling scheme and thus we need operating system different than general purpose one. If you have any more points for the need of server OS please mention. But I don't get why do we need a new CPU Architecture. Why cant Microcomputer CPU architecture do the job. Can someone please clarify? Mini/Mainframe CPU architectures Again I don't know what are these & what miniframes or mainframes used for? I just know they are very big and occupy complete floor. But I never read about some real world problems they are trying to solve. If any one working on one of these. Share your knowledge. Can some one clarify its purpose & why is it that microcomputer CPU archicture not suitable for it? Is there a new kind of operating system for this too? Why? Mixed core CPU architectures Never heard of these. If possible please keep your answer in this format: XYZ CPU architectures Purpose of XYZ Need for a new architecture. why can't current microcomputer CPU architecture work? They go upto 3GHZ & have upto 8 cores. Need for a new Operating System Why do we need a new kind of operating system for this kind of archictures?

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  • nginx - 403 Forbidden

    - by michell90
    I've trouble to get aliases working correctly on nginx. When i try to access the aliases, /pma and /mba (see secure.example.com.conf), i get a 403 Forbidden but the base url works correctly. I read a lot of posts but nothing helped, so here i am. Nginx and php-fpm are running as www-data:www-data and the permissions for the directories are set to: drwxrwsr-x+ 5 www-data www-data 4.0K Dec 5 22:48 ./ drwxr-xr-x. 3 root root 4.0K Dec 4 22:50 ../ drwxrwsr-x+ 2 www-data www-data 4.0K Dec 5 13:10 mda.example.com/ drwxrwsr-x+ 11 www-data www-data 4.0K Dec 5 10:34 pma.example.com/ drwxrwsr-x+ 3 www-data www-data 4.0K Dec 5 11:49 www.example.com/ lrwxrwxrwx. 1 www-data www-data 18 Dec 5 09:56 secure.example.com -> www.example.com/ Im sorry for the bulk, but i thought better too much than too little. Here are the configuration files: /etc/nginx/nginx.conf user www-data www-data; worker_processes 1; error_log /var/log/nginx/error.log; #error_log /var/log/nginx/error.log notice; #error_log /var/log/nginx/error.log info; pid /var/run/nginx.pid; events { worker_connections 1024; } http { include /etc/nginx/mime.types; default_type application/octet-stream; log_format main '$remote_addr - $remote_user [$time_local] "$request" ' '$status $body_bytes_sent "$http_referer" ' '"$http_user_agent" "$http_x_forwarded_for"'; access_log /var/log/nginx/access.log main; sendfile on; keepalive_timeout 65; include /etc/nginx/sites-enabled/*; } /etc/nginx/sites-enabled/secure.example.com server { listen 80; server_name secure.example.com; return 301 https://$host$request_uri; } server { listen 443; server_name secure.example.com; access_log /var/log/nginx/secure.example.com.access.log; error_log /var/log/nginx/secure.example.com.error.log; root /srv/http/secure.example.com; include /etc/nginx/ssl/secure.example.com.conf; include /etc/nginx/conf.d/index.conf; include /etc/nginx/conf.d/php-ssl.conf; autoindex off; location /pma/ { alias /srv/http/pma.example.com; } location /mda/ { alias /srv/http/mda.example.com; } } /etc/nginx/ssl/secure.example.com.conf ssl on; ssl_certificate /etc/nginx/ssl/secure.example.com.crt; ssl_certificate_key /etc/nginx/ssl/secure.example.com.key; ssl_protocols SSLv3 TLSv1 TLSv1.1 TLSv1.2; ssl_ciphers HIGH:!aNULL:!MD5; /etc/nginx/conf.d/index.conf index index.php index.html index.htm; /etc/nginx/conf.d/php-ssl.conf location ~ \.php$ { try_files $uri =404; fastcgi_pass unix:/var/run/php-fpm/php-fpm.sock; fastcgi_index index.php; fastcgi_param HTTPS on; fastcgi_param SCRIPT_FILENAME $request_filename; include fastcgi_params; } /var/log/nginx/secure.example.com.error.log 2013/12/05 22:49:04 [error] 29291#0: *2 directory index of "/srv/http/pma.example.com" is forbidden, client: 176.199.78.88, server: secure.example.com, request: "GET /pma/ HTTP/1.1", host: "secure.example.com" EDIT: forgot to mention, i'm running CentOS 6.4 x86_64 and nginx 1.0.15 Thanks in advance!

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