2 Replies Latest reply on Oct 31, 2012 1:05 AM by jwmitchell

    Solaris memory usage

      Installed Solaris 11.1 and created/booted a single zone. prstat -Z shows the global using about 400 mb of memory and the zone using about 60 mb. Yet top shows that 50% of the 8 gig of available ram used. Is it safe to assume that the remainder is used up by the file system cache? I've read that ZFS implements an aggressive caching algorithm but this seems a tad excessive on an idling system.

      Since my goal is really to use the zones as a playground for Oracle databases on ASM would it be advisable to limit the filesystem cache to a really small amount, such as 0.5 gig?

      I have read several ZFS tuning guides available on the Internet but most of them deal with tuning ZFS to store the database files on the filesystem and little if any when using ASM.
        • 1. Re: Solaris memory usage
          As root:
          echo ::memstat | mdb -k
          That should tell you what's using the memory.

          And yes, limit the ZFS ARC on a server used for Oracle database(s). Half a gig for the ZFS ARC is more than enough.
          • 2. Re: Solaris memory usage

            Adjusted the ARC to max of 400meg. Still can't figure out how a freshly booted system is using over 1gig of RAM.

            This is from top immediately after a reboot - no zones, no apps.

            Memory: 8126M phys mem, 7083M free mem, 8192M total swap, 8192M free swap

            And this is from prtstat -Z
                 0       59  532M  180M   2.1%   0:00:24 0.5% global
            and from memstat
            Page Summary                Pages                MB  %Tot
            ------------     ----------------  ----------------  ----
            Kernel                     203845               796   10%
            ZFS File Data               63992               249    3%
            Anon                        32036               125    2%
            Exec and libs                1408                 5    0%
            Page cache                   6645                25    0%
            Free (cachelist)             8925                34    0%
            Free (freelist)           1763389              6888   85%
            Total                     2080240              8125
            I'm interested primarly because on this same system with OL6.3 booted, it would easily have 7700 meg free. I understand these are different operating systems, but what's taking up 1/8th of the available memory on a freshly booted system?

            Edited by: jwmitchell on Oct 30, 2012 7:59 PM