[removing all lists except ZFS-discuss, as this is really pertinent only
there]
ольга крыжановская wrote:
Are there plans to reduce the memory usage of ZFS in the near future?
Olga
2010/4/2 Alan Coopersmith <alan.coopersm...@oracle.com>:
ольга крыжановская wrote:
Does Opensolaris have an option to install without ZFS, i.e. use UFS
for root like SXCE did?
No. beadm & pkg image-update rely on ZFS functionality for the root
filesystem.
--
-Alan Coopersmith- alan.coopersm...@oracle.com
Oracle Solaris Platform Engineering: X Window System
The vast majority of ZFS memory consumption is for caching, which can be
manually reduced if it's impinging on your application. See the tuning
guide for more info:
http://www.solarisinternals.com/wiki/index.php/ZFS_Evil_Tuning_Guide
As pointed out elsewhere, these tuning parameters are generally for
highwater marks - ZFS will return RAM back to the system if it's needed
for applications. So, in your original problem, the likelihood is /not/
that ZFS is consuming RAM and not releasing it, but rather than your
other apps are overloading the system.
That said, there are certain minimum allocations that can't be reduced
and must be held in RAM, but they're not generally significant. UFS's
memory usage is really not measurably different than ZFS's, so far as I
can measure from a kernel standpoint. It's all the caching that makes
ZFS look like a RAM pig.
One thing though: taking away all of ZFS's caching hurts performance
more than removing all of UFS's file cache, because ZFS stores more than
simple data in it's filecache (ARC).
Realistically speaking, I can't see running ZFS on a machine with less
than 1GB of RAM. I also can't see modifying ZFS to work well in such
circumstances, as (a) ZFS isn't targeted at such limited platforms and
(b) you'd seriously compromise a major chunk of performance trying to
make it fit. These days, 4GB is really more of a minimum for a 64-bit
machine/OS in any case.
I certainly would be interested in seeing what a large L2ARC cache would
mean for reduction in RAM footprint; on one hand, having an L2ARC
requires ARC (i.e. DRAM) allocations for each entry in the L2ARC, but on
the other hand, it would reduce/eliminate storage of actual data and
metadata in DRAM.
Anyone up for running tests for a box with say 512MB of RAM and a 10GB+
L2ARC (in say an SSD)?
--
Erik Trimble
Java System Support
Mailstop: usca22-123
Phone: x17195
Santa Clara, CA
Timezone: US/Pacific (GMT-0800)
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