Robert,
Comments inline...
Robert Milkowski wrote:
Hello Jason,
Wednesday, January 10, 2007, 9:45:05 PM, you wrote:
JJWW> Sanjeev & Robert,
JJWW> Thanks guys. We put that in place last night and it seems to be doing
JJWW> a lot better job of consuming less RAM. We set it to 4GB and each of
JJWW> our 2 MySQL instances on the box to a max of 4GB. So hopefully slush
JJWW> of 4GB on the Thumper is enough. I would be interested in what the
JJWW> other ZFS modules memory behaviors are. I'll take a perusal through
JJWW> the archives. In general it seems to me that a max cap for ZFS whether
JJWW> set through a series of individual tunables or a single root tunable
JJWW> would be very helpful.
Yes it would. Better yet would be if memory consumed by ZFS for
caching (dnodes, vnodes, data, ...) would behave similar to page cache
like with UFS so applications will be able to get back almost all
memory used for ZFS caches if needed.
I guess (and it's really a guess only based on some emails here) that
in worst case scenario ZFS caches would consume about:
arc_max + 3*arc_max + memory lost for fragmentation
This is not true from what I know :-) How did you get to this number ?
From my knowledge it uses :
c_max + (some memory for other caches)
NOTE : (some memory for other caches) is not as large as c_max. It is
probably just x% of it
and not multiples of c_max.
So I guess with arc_max set to 1GB you can lost even 5GB (or more) and
currently only that first 1GB can be get back automatically.
This doesn't seem right based on my knowledge of ZFS.
Regards,
Sanjeev.
_______________________________________________
zfs-discuss mailing list
zfs-discuss@opensolaris.org
http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
