July 16, 201114 yr Hi I'm running Unraid 5.0b7 on a new box with 4 GB of RAM. However i seem to be running out of memory, causing for example sabnzbd to crash several times per day. When I run the top command i get the following output: Mem: 4057380k total, 3843184k used, 214196k free, 187120k buffers And I have no idea what is taking up all my free memory. For example I just shut down a VM running in virtual box, using 1 GB of RAM, and a few minutes after those 1 GB are consumed by 'the void' leaving only a 1-300 MB available... none of the listed processes in the top window shows any unreasonable amount of memory usage. How can I find the sinner? Any help appreciated! syslog.zip
July 16, 201114 yr Author uh.. just noted this line below the memory info line Swap: 0k total, 0k used, 0k free, 3281076k cached does that mean that it is swap taking up all the memory? And if that is the case, is this expected behaviour?
July 16, 201114 yr uh.. just noted this line below the memory info line Swap: 0k total, 0k used, 0k free, 3281076k cached does that mean that it is swap taking up all the memory? And if that is the case, is this expected behaviour? No, it indicates there is no swap space, (as unRAID dores not define a swap device) but that the bulk of memory is being used as disk buffer cache. It is the expected behavior. Linux will buffer as much it can. It will re-use the least-frequently accessed buffer block when a new block is read from the disk. Basically, all it would take to have most of your ram allocated as buffer space is to play a single 4Gig DVD ISO image. No block would be re-read (unless you replayed a chapter) and it would keep everything read into memory as long as it could until you play a different movie.
July 17, 201114 yr Author all right that makes sense. must be something else that causes apps to crash then, than the memory "usage" Thanks Joe L
July 17, 201114 yr It could still be memory issues or more specifically lack of swap space. I've seen apps on linux misbehave badly in the past when there wasn't any swapspace configured. If you're running unmenu, install the unraid-swapfile package. Put the swapfile on the cache drive or an unmanaged drive, never on a parity protected drive. Run like that for a while and see if it helps stability of those apps. Crashing applications could also point toward faulty memory, perhaps you should run memtest if you haven't already.
July 18, 201114 yr No, it indicates there is no swap space, (as unRAID dores not define a swap device) but that the bulk of memory is being used as disk buffer cache. It is the expected behavior. Linux will buffer as much it can. It will re-use the least-frequently accessed buffer block when a new block is read from the disk. JoeL, is there a way to limit this disk buffer cache to a fixed Max size??
July 18, 201114 yr No, it indicates there is no swap space, (as unRAID dores not define a swap device) but that the bulk of memory is being used as disk buffer cache. It is the expected behavior. Linux will buffer as much it can. It will re-use the least-frequently accessed buffer block when a new block is read from the disk. JoeL, is there a way to limit this disk buffer cache to a fixed Max size?? no. It is a Linux feature... Why would you want to limit it? Do you want it to run slower?
July 18, 201114 yr I freaked out at this myself... It works for me... great when i want to rewind a movie if i wander off for a bit or answer the phone and yap for a bit. no buffering lag.
July 18, 201114 yr JoeL, is there a way to limit this disk buffer cache to a fixed Max size?? You shouldn't need to think about this. The disk buffer cache will shrink as needed to give programs the space they request, even before swap space is used.
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