Date: Fri, 16 May 2014 09:27:29 -0500 From: Eric van Gyzen <eric@vangyzen.net> To: Nicolas Haller <nicolas@boiteameuh.org>, <freebsd-stable@freebsd.org> Subject: Re: gmirror + ZFS issues Message-ID: <53762051.30807@vangyzen.net> In-Reply-To: <53761E51.9060908@boiteameuh.org> References: <5376115D.5050704@boiteameuh.org> <53761477.70205@denninger.net> <53761E51.9060908@boiteameuh.org>
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On 05/16/2014 09:18, Nicolas Haller wrote: > On 16/05/2014 09:36, Karl Denninger wrote: >> >> On 5/16/2014 8:23 AM, Nicolas Haller wrote: >>> Hello, >>> >>> I've got a new server and I installed FreeBSD 10 on it. I have a >>> problem to create a new zfs pool. The command stalls on IO wait (D >>> state / zio->io_cv). >>> >>> The device for the pool is a 1.7T partition (index 4) of a gmirror >>> device. >> Why? >> >> ZFS provides its own mirroring and it is superior, as it checksums each >> block and thus does not rely on the drive returning an error to detect >> problems. It can also rewrite a bad block (assuming the problem is >> transient) and scrub also relies on independent components. >> >> You're destroying the data integrity advantage that ZFS gives you by >> using a gmirror under it. Stop doing that and see if your problem >> disappears. >> >> (In other words it sounds like the problem is real but you shouldn't be >> doing that anyway, so it also shouldn't bite you.) >> > > Yes you're right but I have two disks on this server which host my > non-zfs root fs. The first 98G partition you show on "gpart show" > output is my UFS root fs and I want it mirrored. > > As I'm not sure it's a good idea to mix gmirror and ZFS mirror on the > same drives (What do you think about this?), I let gmirror handle the > mirror thing. I use gmirror for swap and a ZFS mirror for all file systems. It works quite well. I suspect it would work equally well for your setup. Eric $ gpart show => 34 488281183 ada0 GPT (232G) 34 6 - free - (3.0k) 40 256 1 freebsd-boot (128k) 296 31457280 2 freebsd-swap (15G) 31457576 456823640 3 freebsd-zfs (217G) 488281216 1 - free - (512B) => 34 488281183 ada1 GPT (232G) 34 6 - free - (3.0k) 40 256 1 freebsd-boot (128k) 296 31457280 2 freebsd-swap (15G) 31457576 456823640 3 freebsd-zfs (217G) 488281216 1 - free - (512B) $ gmirror status Name Status Components mirror/swap COMPLETE gpt/swap1 (ACTIVE) gpt/swap2 (ACTIVE) $ zpool status pool: root1 state: ONLINE scan: scrub repaired 0 in 0h42m with 0 errors on Mon Mar 10 12:18:11 2014 config: NAME STATE READ WRITE CKSUM root1 ONLINE 0 0 0 mirror-0 ONLINE 0 0 0 gpt/root1 ONLINE 0 0 0 gpt/root2 ONLINE 0 0 0
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