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Date:      Thu, 23 Feb 2012 00:56:24 -0800
From:      =?iso-8859-1?Q?Ask_Bj=F8rn_Hansen?= <ask@develooper.com>
To:        Artem Belevich <art@freebsd.org>
Cc:        freebsd-stable@freebsd.org, freebsd-zfs@freebsd.org
Subject:   Re: Can't read a full block, only got 8193 bytes.
Message-ID:  <1E0D6546-49DE-478C-9759-FE496B1F0DB8@develooper.com>
In-Reply-To: <CAFqOu6iLe=a9Xi9qi2rsLz_KL_P2jjK1BZKUu0dBPnzj-9ET-Q@mail.gmail.com>
References:  <770EEEFF-B41D-4851-AD74-C3F96FFB1683@develooper.com> <CAFqOu6iLe=a9Xi9qi2rsLz_KL_P2jjK1BZKUu0dBPnzj-9ET-Q@mail.gmail.com>

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On Feb 19, 2012, at 12:10, Artem Belevich wrote:

[...]
>> "Can't read a full block, only got 8193 bytes."
>=20
> That's probably just a side effect of ZFS checksum errors. ZFS will
> happily read the file until it hits a record with checksum. If
> redundant info is available (raidz or mirror), ZFS will attempt to
> recover your data. If there's no redundancy you will get read error.
> If you do "zpool status -v" you should see list of files affected by
> corruption.

Hi Artem,

Thank you for the reply and the tips!  =20

That makes sense and explains why we'd just get checksum errors on a =
raidz1 test (but bonnie++ was happy except things were slow), but had =
the weird errors on a single disk pool.

>> This seems to only be when testing a single ZFS disk or a UFS =
partition.  Testing a raidz1 we just get checksum errors noted in zpool =
status, but no errors reading (though read speeds are ~10MB/second =
across four disks -- writing sequentially was ~230MB/second).
>>=20
>> Any ideas where to start look?
>=20
> You need to figure out why you're getting checksum errors. Alas
> there's probably no easy way to troubleshoot it. The issue could be
> hardware related and possible culprits may include bad RAM, bad SATA
> cables, quirks of particular firmware revision on disk controller
> and/or hard drive.

Replacing the 3ware controller with a basic LSI controller fixed the =
problems and improved performance, so I guess the 3ware controller =
doesn't play nice with the Seagate 3TB disks (they're not on their =
compatibility list).


Ask




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