Rich Freeman on 25 Apr 2016 17:33:16 -0700


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Re: [PLUG] [plug-announce] TOMORROW - Tue, Apr 19, 2016: PLUG North - "Linux Containers" by Jason Plum and Rich Freeman (*6:30 pm* at CoreDial in Blue Bell) 

On Mon, Apr 25, 2016 at 7:46 PM, Keith C. Perry
<kperry@daotechnologies.com> wrote:
>
> Therefore, while it may be technically correct to say one file system is better than another, practically speaking talking about bit flips from cosmic ray isn't alone enough of a motivator to choose one file system over another (assuming you can definitively say that a particular file system is better suited to handle randomly occurring bit flips). XFS has error detection and redundancy, I think EXT4 does too.  Of course BTRFS and ZFS do so that's simply not enough of a practical argument when other parts of data storage and retrieve process also have some level of these functions.

As far as I'm aware neither xfs nor ext4 support redundancy.  If you
have a citation to the contrary by all means provide it.  You can run
them on top of RAID, but every RAID implementation I'm aware of can't
handle silent bit flips.  If the drive doesn't return an error then
they assume the data must be good.

If course you could create a device-level RAID implementation that
supports block-level checksumming and failover, but as far as I'm
aware nobody has actually done it.

> I agree, bad data and corrupt data are not the same and point is that a silent failure at the file system layer would treat good, bad and corrupt data equally.

The only guarantee that btrfs provides is that whatever you write to
it gets read back.  It WILL detect silent failure past this point, but
of course if you overwrite data/etc from userspace it will happily do
so.

-- 
Rich
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