On Jul 16, 2013, at 11:42 AM, Warren Block wrote: > On Tue, 16 Jul 2013, aurfalien wrote: >> On Jul 16, 2013, at 2:41 AM, Shane Ambler wrote: >>> >>> I doubt that you would save any ram having the os on a non-zfs drive as >>> you will already be using zfs chances are that non-zfs drives would only >>> increase ram usage by adding a second cache. zfs uses it's own cache >>> system and isn't going to share it's cache with other system managed >>> drives. I'm not actually certain if the system cache still sits above >>> zfs cache or not, I think I read it bypasses the traditional drive cache. >>> >>> For zfs cache you can set the max usage by adjusting vfs.zfs.arc_max >>> that is a system wide setting and isn't going to increase if you have >>> two zpools. >>> >>> Tip: set the arc_max value - by default zfs will use all physical ram >>> for cache, set it to be sure you have enough ram left for any services >>> you want running. >>> >>> Have you considered using one or both SSD drives with zfs? They can be >>> added as cache or log devices to help performance. >>> See man zpool under Intent Log and Cache Devices. >> >> This is a very interesting point. >> >> In terms if SSDs for cache, I was planning on using a pair of Samsung Pro >> 512GB SSDs for this purpose (which I haven't bought yet). >> >> But I tire of buying stuff, so I have a pair of 40GB Intel SSDs for use as >> sys disks and several Intel 160GB SSDs lying around that I can combine with >> the existing 256GB SSDs for a cache. >> >> Then use my 36x3TB for the beasty NAS. > > Agreed that 256G mirrored SSDs are kind of wasted as system drives. The 40G > mirror sounds ideal.
Update; I went with ZFS as I didn't want to confuse the toolset needed to support this server. Although gmirror is not hard to figure out, I wanted consistency in systems. So I've a booted 9.1 rel using a mirrored ZFS system disk. The drives do support TRIM but am unsure how this plays with ZFS. I did the standard partition scheme of; root@kronos:/root # gpart show => 34 78165293 da0 GPT (37G) 34 128 1 freebsd-boot (64k) 162 6 - free - (3.0k) 168 8388608 2 freebsd-swap (4.0G) 8388776 69776544 3 freebsd-zfs (33G) 78165320 7 - free - (3.5k) => 34 78165293 da1 GPT (37G) 34 128 1 freebsd-boot (64k) 162 6 - free - (3.0k) 168 8388608 2 freebsd-swap (4.0G) 8388776 69776544 3 freebsd-zfs (33G) 78165320 7 - free - (3.5k) At any rate, thank you for the replies, very much appreciate it. Especially since building a rather large production worthy NAS not knowing a lick of freeBSD. The reasons going with freeBSD are 2 fold; ZFS stability,seems a better marriage then ZOL. Correctly provides NFS pre attributes on write reply; mtime. Linux does not. While its a steep learning curve, the 2 points above require the use of freeBSD or alike. - aurf _______________________________________________ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to "freebsd-questions-unsubscr...@freebsd.org"