Rich Freeman on 26 Apr 2016 03:32:25 -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 11:37 PM, Keith C. Perry
<kperry@daotechnologies.com> wrote:
> The redundancy in the in redundancy bits for the error correction.  See section 4.1 of this paper:
>
> http://pages.cs.wisc.edu/~vshree/xfs.pdf
>

As far as I can tell that section only describes a taxonomy for the
levels of error detection and recovery any hypothetical filesystem
COULD have, not the features of XFS itself.  If you look at the
following sections you'll see that there is little redundancy in the
data that xfs stores (it sounds like it is mainly just the superblock
- as with most filesystems), and when there is redundancy it generally
isn't used automatically for recovery.

If you look at figures 3-6 you'll see that the best form of recovery
they even observed was fixing some errors at time of remount.

Both zfs and btrfs redundantly store ALL metadata (I know btrfs even
does this by default on a single disk, but with multiple disks it
ensures redundant copies are on different disks), and everything is
checked on read.

>
> Finally, an article from January 2012 discussing why XFS will probably become the default file system over EXT4 and why in the future it will probably be BTRFS if all the issues can be worked out.  I only include it to illustrate how people get wrapped in the religious fight while ignoring the fact that there is a lot that goes into the process so saying "my god is more reliable that your god" gets a bit too far into the weeds.  Funny how that always happens.  :D

The main thing that has kept me away from xfs is the fact that you
can't shrink the filesystem.  That can be a major inconvenience when
you're moving disks around.  I've run it in the past and it works
reasonably well in general, but for my generic reliable filesystem I
stick with ext4.

-- 
Rich
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