ZFS obn FreeBSD hardware model for 48 or 96 sata3 paths...

Artem Belevich art at freebsd.org
Mon Sep 19 21:37:48 UTC 2011

On Mon, Sep 19, 2011 at 1:27 PM, Freddie Cash <fjwcash at gmail.com> wrote:
>> Can I explicitly cache metadata/dirs in RAM, and cache file data in L2ARC ?
> No.  Data that does not go into the ARC can never go into the L2ARC.  IOW,
> if you set primarycache=metadata and secondarycache=data, you will never see
> anything in L2ARC.
> At least, that's the understanding I've come to based on posts on the
> zfs-discuss mailing list.  And it does jive with what I was seeing on our
> storage servers.

Indeed. I didn't think of that. L2ARC is populated by the data that
gets evicted from ARC. So, if ARC is metadata only, whatever spills
into L2ARC would be metadata only, too...

> It's too bad, because it would be a nice setup, ordered from fastert to
> slowest:  ARC for metadata, L2ARC for file data, pool for permanent storage.

That would indeed be nice.


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