[zfs-discuss] ZFS eating up all 16 GB RAM when combining 4k blocksize ZVOL with XFS
simar at gmx.net
Tue Nov 13 10:22:19 EST 2018
> I would recommend using the 0.7.11 dkms versions of zfs and spl. Too
> many new features and setups in there.
I'm sure the Ubuntu team backports any critical fix. Just the enterprise
Linux thing of never raise the version number. But I agree with you
there were some important fixes between 0.7.5 and 0.7.11.
> The ARC *will* take up at least half your RAM if you do not limit it
> in your grub.cfg moreso if youve got zraid setups going on.
Well I want that to happen. In this setup the only thing that should use
RAM are ZFS and XFS or SCST for iSCSI. But I am still puzzled that this
setup can use more than double the configured ARC size in a matter of
> As for XFS - Im not sure whats happening there. Shouldnt be anything
> too crazy.
> On Mon, Nov 12, 2018, 18:07 Paul Gorman <pagorman at asu.edu
> <mailto:pagorman at asu.edu> wrote:
> Add to the grub/rEfind boot args for the kernel:
> zfs.zfs_arc_max=536870912 #(for 512MB cap zfs memory usage,
> expressed in bytes)
> Though you'll likely want 512MiB-1GiB per physical disk.
Yes with this low setting it works. I would really like to use more of
the RAM as ARC.
If possible the ZFS/SPL code should not just use all available free RAM
and then some more out of the blue. Seems at least there has to be a
different default value than half the RAM if there are reproducable
cases where that just more than doubles. No user expects the filesystem
code to just exhaust all memory. Swap changes nothing in this respect by
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