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How much memory is needed for vB5?

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  • How much memory is needed for vB5?

    Since upgrading to vB5, I'm getting a lot of crashes. My current memory usage is: Mem: 1024 793 230 0 38 507 Here are the error messages I've gotten:

    May 7 23:20:43 server kernel: lowmem_reserve[]: 0 0 0 0

    May 7 23:20:43 server kernel: lowmem_reserve[]: 0 0 0 0

    May 7 23:20:43 server kernel: lowmem_reserve[]: 0 0 0 0

    May 7 23:20:43 server kernel: lowmem_reserve[]: 0 0 0 0

    May 8 10:10:24 server kernel: xen_mem: Initialising balloon driver.

    May 8 10:10:25 server kernel: Non-volatile memory driver v1.2

    How much memory do I need to run vB5?


  • #2
    Enough to power the server its running on. Kind of hard to give a specific answer. I run vB5 on a few small servers without much traffic and they use under 1gb.


    • #3
      You want at least 2GBs, for both vB4 and vB5.


      • #4
        I believe you're running into Linux OOM (out of memory killer) which partially comes down to how your virtualized server container configured and sets up it's memory handling and limits. Common one is on 32bit virtualized server's where they don't configure any swap space (0 swap size) i.e. older OpenVZ based VPS which don't have vswap support.

        i.e. if you have 32GB of memory with 0 swap size, OOM default limit for committed memory usually would be (total memory/2) + swap size so 32/2 + 0 = 16GB limit, once committed memory hits 16GB, you'd start getting OOM low mem errors

        The way the OOM killer works is you can run into such low memory reserve errors even if you have alot of memory. it's triggered when free memory limit falls below the the low memory limit as seen below. Then OOM Killers picks whatever is the largest consuming process which isn't necessarily the offending process to kill.

        Below is from logs on from techspot's server optimisation request here which had same problem In this case it's mysql server process that got killed off

        Aug 16 17:01:30 techspot04 kernel: lowmem_reserve[]: 0 0 3030 3030
        Aug 16 17:01:30 techspot04 kernel: Node 0 Normal free:22164kB min:22568kB low:28208kB high:33852kB active_anon:2326748kB inactive_anon:583424kB active_file:996kB inactive_file:10740kB unevictable:0kB isolated(anon):384kB isolated(file):0kB present:3102720kB mlocked:0kB dirty:0kB writeback:0kB mapped:3124kB shmem:1624676kB slab_reclaimable:22588kB slab_unreclaimable:44460kB kernel_stack:3648kB pagetables:33728kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:32 all_unreclaimable? no
        Are you on a VPS server using Xen or KVM or OpenVZ etc ? Looks like Xen VPS from your errors ?

        If using OpenVZ VPS please note memory usage is different that other virtualization or non-virtualized platforms, in that there is no differentiation between virtual and resident memory, so all the virtual memory is counted as RAM. With default linux stack size of 10MB on OpenVZ, this can lead to excessive reported memory usage for multi-threaded apps such as Memcached server, MySQL etc.

        You can see an example of OpenVZ's memory usage when I did a review on BuyVM's OpenVZ based VPS server on my personal blog at

        As to how much memory, depends on your forum size, forum concurrent activity and how your server's memory management is configured and set up. I'd say to be comfortable you'd want real 1GB of memory properly configured and available to you per 1 instance of vB5 forum install.

        :: Always Back Up Forum Database + Attachments BEFORE upgrading !
        :: Nginx SPDY SSL - World Flags Demo [video results]
        :: vBulletin hacked forums: Clean Up Guide for VPS/Dedicated hosting users [ blog summary ]


        • #5
          Marvelous! That has made everything so clear.


          • #6
            Originally posted by DemOnstar View Post
            Marvelous! That has made everything so clear.
            To be fair, if you don't understand what he's saying, you shouldn't be running a live site on a VPS.


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