solaris with ZFS and informix DB memory issue.

LinuxLover · 03-10-2010, 02:05 AM

Hi,

We are using Solaris 10 5/09 s10s_u7wos_08 SPARC

Patch level Generic_142900-02 (Dec 09 PatchCluster release)

Informix DB version 11.5FC6

OS File systems ZFS

System is connected with SAN wich is also configured with ZFS in OS.

Now Problem is Memory

Total memory in system Memory size: 32640 Megabytes

vmstat displays that only 4 GB is left

Code:

vmstat 1 3
 kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr s0 s4 sd --   in   sy   cs us sy id
 0 0 0 23060608 11491848 5 16 0 0  0  0  0  1 -0 27  0 1063 1777  901  0  0 100
 0 0 0 12122312 4326912 8 20 0  0  0  0  0  0  0  8  0 1163 3830  948  0  0 99
 0 0 0 12121992 4326656 0 1  0  0  0  0  0  0  0  7  0 1136 3308  787  0  0 100

While informix is using just 5 to 6 GB and no other process on the system is using significant memory.

On thoroughly investigating I found

Code:

mdb -k
Loading modules: [ unix genunix specfs dtrace zfs sd mpt px ldc ip hook neti sctp arp usba fcp fctl emlxs nca ssd lofs md cpc random crypto fcip logindmux ptm ufs sppp nfs ipc ]
> ::memstat
Page Summary                Pages                MB  %Tot
------------     ----------------  ----------------  ----
Kernel                     240843              1881    6%
ZFS File Data             3163768             24716   77%
Anon                        99395               776    2%
Exec and libs                5218                40    0%
Page cache                  33874               264    1%
Free (cachelist)           296163              2313    7%
Free (freelist)            262696              2052    6%

Total                     4101957             32046
Physical                  4070982             31804

ZFS File Data is using most of the memory.

Kindly help me what is that ? Is it normal behaviour ?

jlliagre · 03-10-2010, 05:37 AM

Yes. Unused memory is wasted memory anyway.

LinuxLover · 03-10-2010, 11:49 PM

Hi jlliagre,

Thanks for your reply.

Is the ZFS File Data memory is like the system cache memory.Which become available when required.

This is our main DB machine and memory is heavily demanded by databases on that.

jlliagre · 03-11-2010, 02:23 AM

That's it. Most of this memory is used by the ZFS ARC cache and this memory is made available to processes if demand occurs.

Note that you can limit the ARC cache size which make sense in some situations:

http://www.solarisinternals.com/wiki..._the_ARC_Cache