Look at alternate cachefiles ('zpool set cachefile', 'zpool import -c
<cachefile>', etc). This avoids scanning all devices in the system and
instead takes the config from the cachefile.
- Eric
On Tue, May 20, 2008 at 05:20:52PM -0400, Chris Siebenmann wrote:
> We're planning to build a ZFS-based Solaris NFS fileserver environment
> with the backend storage being iSCSI-based, in part because of the
> possibilities for failover. In exploring things in our test environment,
> I have noticed that 'zpool import' takes a fairly long time; about
> 35 to 45 seconds per pool. A pool import time this slow obviously
> has implications for how fast we can import a bunch of pools during
> a failover situation, so I'd like to speed it up somehow (ideally in
> non-hacky ways).
>
> (Trying to do all of the 'zpool import's in parallel doesn't seem
> to speed the collective set of them up relative to doing them
> sequentially.)
>
> My test environment currently has 132 iSCSI LUNs (and 132 pools, one
> per LUN, because I wanted to test with extremes) on an up to date S10U4
> machine. A truss of a 'zpool import' suggests that it spends most of
> its time opening various disk devices and reading things from them and
> most of the rest of the time doing modctl() calls and ZFS ioctls().
>
> (Also, using 'zpool import -d' with a prepared directory that has only
> symlinks to the particular /dev/dsk device entries for a pool's LUN
> speeds things up dramatically.)
>
> So, are there any tricks to speeding up ZFS pool import here (short of
> the 'zpool import -d' stuff)? Would Sun Cluster manage this faster, or
> does its ZFS pool failover stuff basically reduce to 'zpool import' too?
>
> Thanks in advance.
>
> - cks
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--
Eric Schrock, Fishworks http://blogs.sun.com/eschrock
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