On 10/24/2013 01:59 PM, John R Pierce wrote:
> 1) you need a LOT of ram for decent performance on large zpools. 1GB ram
> above your basic system/application requirements per terabyte of zpool
> is not unreasonable.
That seems quite reasonable to me. Our existing equipment has far more
than enough RAM to make this a comfortable experience.
> 2) don't go overboard with snapshots. a few 100 are probably OK, but
> 1000s (*) will really drag down the performance of operations that
> enumerate file systems.
Our intended use for snapshots is to enable consistent backup points,
something we're simulating now with rsync and its hard-link option. We
haven't figured out the best way to do this, but in our backup clusters
we have rarely more than 100 save points at any one time.
> 3) NEVER let a zpool fill up above about 70% full, or the performance
> really goes downhill.
Thanks for the tip!
> (*) ran into a guy who had 100s of zfs 'file systems' (mount points),
> per user home directories, and was doing nightly snapshots going back
> several years, and his zfs commands were taking a long long time to do
> anything, and he couldn't figure out why. I think he had over 10,000
> filesystems * snapshots.
Wow. Couldn't he have the same results by putting all the home
directories on a single ZFS partition?
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