Date: Mon, 20 May 2013 19:18:49 +0400 (MSK) From: Dmitry Morozovsky <marck@rinet.ru> To: Josh Beard <josh@signalboxes.net> Cc: freebsd-fs@freebsd.org Subject: Re: L2ARC and ZIL on same SSD? Message-ID: <alpine.BSF.2.00.1305201913450.99840@woozle.rinet.ru> In-Reply-To: <CAHDrHSv-%2BPjLiPcZrE7CJx85Qyo%2B%2BYv%2Bc_1myNH_mZ1nS5Xwog@mail.gmail.com> References: <CAHDrHSv-%2BPjLiPcZrE7CJx85Qyo%2B%2BYv%2Bc_1myNH_mZ1nS5Xwog@mail.gmail.com>
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On Mon, 20 May 2013, Josh Beard wrote:
> I have a file server running 9.1-RELEASE with 24 GB of RAM and a 6 TB zpool
> spread across 12 500GB disks in two raidz1 and 2 spares. This server
> houses hundreds of home directories for end-users and stays pretty busy
> with both read and writes.
>
> I'm planning to add two SSDs soon (128 GB each) to help performance and was
> planning to mirror them. I was curious if having the L2ARC and ZIL on the
> same disks (mirrored) is okay. With some searching, I haven't seen any
> "official" word on this. I've seen some folks say not to and others
> recommend it. Adding a second set of SSDs isn't desirable, as I'll start
> cutting into my available storage capacity (16 bay system).
>
> Any advice or experience with this?
Well, no official words, but -- I use the following setup for our new database
server, very similar to yours (but RAID10-alike as it's database, not generic
storage):
root@briareus:/usr/local/etc# zpool status
pool: br
state: ONLINE
scan: scrub repaired 0 in 0h0m with 0 errors on Fri Apr 26 15:29:32 2013
config:
NAME STATE READ WRITE CKSUM
br ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
gpt/br0 ONLINE 0 0 0
gpt/br4 ONLINE 0 0 0
mirror-1 ONLINE 0 0 0
gpt/br1 ONLINE 0 0 0
gpt/br5 ONLINE 0 0 0
mirror-2 ONLINE 0 0 0
gpt/br6 ONLINE 0 0 0
gpt/br2 ONLINE 0 0 0
mirror-3 ONLINE 0 0 0
gpt/br3 ONLINE 0 0 0
gpt/br7 ONLINE 0 0 0
logs
mirror-4 ONLINE 0 0 0
gpt/br-zil0 ONLINE 0 0 0
gpt/br-zil1 ONLINE 0 0 0
cache
gpt/br-cache0 ONLINE 0 0 0
gpt/br-cache1 ONLINE 0 0 0
errors: No known data errors
root@briareus:/usr/local/etc# glabel status | egrep 'zil|cache'
gpt/br-zil0 N/A da8p1
gpt/br-cache0 N/A da8p2
gpt/br-zil1 N/A da9p1
gpt/br-cache1 N/A da9p2
root@briareus:/usr/local/etc# gpart show da8 da9
=> 34 234371453 da8 GPT (111G)
34 2014 - free - (1M)
2048 16777216 1 freebsd-zfs (8.0G)
16779264 217591808 2 freebsd-zfs (103G)
234371072 415 - free - (207k)
=> 34 234371453 da9 GPT (111G)
34 2014 - free - (1M)
2048 16777216 1 freebsd-zfs (8.0G)
16779264 217591808 2 freebsd-zfs (103G)
234371072 415 - free - (207k)
... and it's working pretty well, givins us some tens of kIOPs on database
writes.
--
Sincerely,
D.Marck [DM5020, MCK-RIPE, DM3-RIPN]
[ FreeBSD committer: marck@FreeBSD.org ]
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*** Dmitry Morozovsky --- D.Marck --- Wild Woozle --- marck@rinet.ru ***
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