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Server crashes since installing WPMU

I recently converted my wordpress blogs into MU. They run just fine for a few days and then the server suddenly becomes completely unresponsive and I have to do a hard reboot.

I haven’t changed anything else on the system other than switching to MU and there are only two blogs in the MU install. Nothing shows up in the apache logs or system logs.

I’m not getting any messages about the system being out of swap space so I really don’t know what’s the problem.

At this point I’m pretty certain that I’m going to revert back to regular WP. Does anyone have ideas on what would cause it or how to track down the problem and fix it?

Tue, 11 Aug 2009 4:56:31
  • lucidology
    • WPMU DEV Initiate

    Hi, it’s a slicehost 256 slice with 256MB ram and 10GB disk space.

    The thing that bothers me is that nothing appears to be written to the logs, so even if I were to get a huge machine I really don’t know if it would help with the problem.

  • lucidology
    • WPMU DEV Initiate

    I’ve backed one of the MU blogs back to normal WP, here’s what top says:

    top - 06:53:40 up 2:22, 1 user, load average: 0.08, 0.05, 0.01

    Tasks: 101 total, 1 running, 100 sleeping, 0 stopped, 0 zombie

    Cpu(s): 0.0%us, 0.1%sy, 0.0%ni, 99.7%id, 0.0%wa, 0.0%hi, 0.0%si, 0.2%st

    Mem: 262364k total, 211472k used, 50892k free, 10724k buffers

    Swap: 524280k total, 265292k used, 258988k free, 30772k cached

    PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND

    7558 www-data 20 0 275m 31m 4944 S 0 12.3 0:02.54 apache2

    7639 www-data 20 0 274m 30m 5156 S 0 11.9 0:00.48 apache2

    7613 www-data 20 0 274m 30m 5160 S 0 11.9 0:00.94 apache2

    7651 www-data 20 0 264m 20m 3992 S 0 8.1 0:00.42 apache2

    3692 mysql 20 0 294m 14m 2796 S 0 5.7 0:15.97 mysqld

    7442 root 30 10 66320 7624 848 S 0 2.9 0:00.50 python

    4157 root 20 0 252m 5200 2956 S 0 2.0 0:02.62 apache2

    5785 www-data 20 0 278m 4496 4344 S 0 1.7 0:01.42 apache2

    5786 www-data 20 0 279m 4492 4340 S 0 1.7 0:01.70 apache2

    5783 www-data 20 0 275m 4472 4320 S 0 1.7 0:01.78 apache2

    5684 www-data 20 0 275m 3916 3776 S 0 1.5 0:00.58 apache2

    5493 www-data 20 0 276m 3908 3772 S 0 1.5 0:02.86 apache2

    5545 www-data 20 0 273m 3880 3744 S 0 1.5 0:01.32 apache2

    5699 www-data 20 0 275m 3880 3744 S 0 1.5 0:00.62 apache2

    5736 www-data 20 0 275m 3828 3688 S 0 1.5 0:00.56 apache2

    7652 www-data 20 0 252m 3712 1212 S 0 1.4 0:00.00 apache2

    7653 www-data 20 0 252m 3712 1212 S 0 1.4 0:00.00 apache2

    7654 www-data 20 0 252m 3712 1216 S 0 1.4 0:00.00 apache2

    7655 www-data 20 0 252m 3712 1212 S 0 1.4 0:00.00 apache2

    7643 postfix 20 0 52020 3004 2332 S 0 1.1 0:00.00 cleanup

    7660 www-data 20 0 252m 2988 620 S 0 1.1 0:00.00 apache2

  • Ovidiu
    • Code Wrangler

    look at it this way: your top 4 apache processes use 20-31 MB of RAM. lets asume an average of 25MB.

    Say you have 10 simultaneous visitors. They’d eat up all your RAM so any other process requiring RAM would get swapped out :slight_smile: 10x 25MB =250MB and what about the rest of your applications? mysql and other proceses… they need RAM too

    that is the way to look at it :slight_smile:

  • drmike
    • DEV MAN’s Mascot

    Running out of memory was the first thing that came to my mind though. Between the apache, mysql and php processes along with whatever is being run for the hosting software, 256 meg is rather tight. At least 512 would be a good start along with some random monitoring.

    To be honest, I don;t find file caching to help much with memory usage. Adjusting child numbers did help. Moot though as the project in that other thread got scraped.

  • Ovidiu
    • Code Wrangler

    yepp, caching doesn’t help in this case, because it doesn’t matter if apache serves php files or static html files, it is still bloated up to i.e. 25MB

    to circumvent you’d use a small and lightweight webserver as a frontend ot apache that serves images and cahced files and hands everything else over to apache but that is a rather advanced subject