what is data storage?
ASS U ME the root is local hdd

On 5/17/2012 3:31 PM, Hung-Sheng Tsao Ph.D. wrote:

it  will depend on how zfs is used in the system
1)root zpool only?
2)Db files also?
3)Is this RAC configuration?

On 5/17/2012 3:19 PM, Paynter, Richard wrote:

I have a customer who wants to set zfs_arc_max to 1G for a 16G system, and 2G for a 32G system. Both of these are SAP and/or Oracle db servers. They apparently want to maximize the amount of memory available for the applications.

My question, now, is whether it would be advisable to do this, and – if not – what the impact might be.

The 32G system is an M3000; the 16G system is a V490. Both are running Solaris 10 Update 8, patched to 147440-09.

I have a feeling that setting zfs_arc_max this low is not a good idea, but would like to get some corroborating information/references, if possible.



*From:* [] *On Behalf Of *Richard Elling
*Sent:* Thursday, May 17, 2012 11:24 AM
*To:* Paul Kraus
*Cc:* ZFS Discussions
*Subject:* Re: [zfs-discuss] zfs_arc_max values

On May 17, 2012, at 5:28 AM, Paul Kraus wrote:

On Wed, May 16, 2012 at 3:35 PM, Paynter, Richard
< <>> wrote:

Does anyone know what the minimum value for zfs_arc_max should be set to?

    Does it depend on the amount of memory on the system, and – if so
    – is there

    a formula, or percentage, to use to determine what the minimum
    value is?

   I would assume that it should not be set any lower than `kstat
zfs::arcstats:c_min`, which I assume you can set with zfs_arc_min in
/etc/system, but that does not really answer your question.

arc_c_max and arc_c_min are used for different things. If you make significant

changes there, then it is a good idea to set both zfs_arc_min, zfs_arc_max, and

zfs_arc_meta_limit as a set.

NB, the minimum size of these is 64MB.

 -- richard


ZFS Performance and Training <>


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