On Sat, Oct 26, 2013 at 4:36 PM, Ray Van Dolson <rayvd at bludgeon.org> wrote: > On Thu, Oct 24, 2013 at 01:59:15PM -0700, John R Pierce wrote: > > On 10/24/2013 1:41 PM, Lists wrote: > > > Was wondering if anybody here could weigh in with real-life experience? > > > Performance/scalability? > > > > I've only used ZFS on Solaris and FreeBSD. some general > observations... > > > > 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. > > > > 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. > > > > 3) NEVER let a zpool fill up above about 70% full, or the performance > > really goes downhill. > > Have run into this one (again -- with Nexenta) as well. It can be > pretty dramatic. We tend to set quotas to ensure we don'get exceed 75% > or so max, but.... > > > We maybe getting a bit off topic here but on that subject we have noticed a significant degrade in performance on systems running at 75-80 % of their pool capacity. I understand that the nature of COW will increase fragmentation. On large storages though 70% out of 100TB means that you have to always maintain 30TB free which is not a small number in terms of cost per TB. - George Kontostanos ---