Re: [gentoo-user] BTRFS problem? [WAS Quick check on net-print/hplip-3.14.10]

[Rich Freeman <rich0@gentoo.org>]

On Fri, Sep 18, 2015 at 1:56 PM, Mick <michaelkintzios@gmail.com> wrote:
> On Friday 18 Sep 2015 17:16:54 Marc Joliet wrote:
>> On Friday 18 September 2015 10:31:01 Mick wrote:
>> >A couple of months ago the akonadi DB went sideways and kmail played up as
>> >a result.  Again I was suspicious of btrfs, but neither the logs nor fsck
>> >showed up anything.
>>
>> I take it "btrfs scrub" didn't turn up anything, or is that what you meant
>> by fsck?
>
> Am I supposed to run scrub with I do not have a RAID running?  I thought scrub
> was meant for comparing checksums between mirrored fs - have I got this wrong?
>

You can actually run scrub on a non-raid btrfs setup.  Btrfs will
report any errors that it detects (using the checksumming in the
filesystem), but it would not be able to fix errors unless you have it
storing redundant data somewhere (even on non-raid it still stores
redundant metadata by default, and you can choose to do this with data
as well which protects against block-level failures but not disk-level
failures, obviously).

However, you'd have gotten the same errors in dmesg just trying to
read the files - btrfs checks the checksum on all file read
operations.  That is a big part of the value of both btrfs and zfs.

-- 
Rich