Date: Fri, 16 May 2014 10:18:57 -0400 From: Nicolas Haller <nicolas@boiteameuh.org> To: freebsd-stable@freebsd.org Subject: Re: gmirror + ZFS issues Message-ID: <53761E51.9060908@boiteameuh.org> In-Reply-To: <53761477.70205@denninger.net> References: <5376115D.5050704@boiteameuh.org> <53761477.70205@denninger.net>
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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. So, yes, I drop the data integrity advantage, but I keep the flexibility given by pools/datasets, send/receive, compression... It's not so bad :-) -- Nicolas Haller
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