Re: [BackupPC-users] What file system do you use?

[Timothy J M. <tm...@ob...>]

Mark Rosedale <mro...@vi...> wrote on 12/16/2013 09:06:07 AM:

> I'm working on bringing back a backuppc instance. It is very large 3
> +TB. The issue I'm having is e2fsck is taking an extremely long time
> to finish. It is stuck on the checking directory structure. We are 
> going on 48 hours. 

How much RAM do you have?  This can make a very large difference.  a 3+TB 
drive can need 4GB or more to complete in a reasonable amount of time.

> So I'm wondering what other file systems do you guys use? Any 
> recommendations of one that may be more efficient or better suited 
> for such a large volume on Bakcuppc? Because once I have this 
> machine back up I'm actually going to add more drives. 

I use EXT3 because I'm conservative.  I've had problems with EXT4 crashing 
more often than EXT3 in the event of flaky hardware.  Make no mistake: the 
fault was the hardware, but I found that EXT3 was much more tolerant of 
that (or EXT4 more sensitive).

I have limited experience with XFS.  I have lots of experience with JFS 
(both on Linux and as a long-time OS/2 user in the past:  that's where the 
Linux JFS filesystem came from), but given its relatively small visibility 
I stay away from it in backup scenarios.

So for me, it's humble EXT3 and recently a couple of EXT4 servers.  That 
is getting to be a problem, though:  I already have a couple of servers 
where I have had to partition the server into separate partitions because 
of the 16TB limit with EXT3 (and the practical 16TB limit with EXT4 and 
user-space tools).

Reference for RHEL file size limits as of September, 2013:  
https://access.redhat.com/site/solutions/1532 .  That link has this 
interesting tidbit: "The solution for large filesystems is to use XFS. The 
XFS file system is specifically targeted at very large file systems (16 TB 
and above)."

Red Hat has already dropped JFS support in the installer, and I understand 
that XFS will be the default in RHEL7.  It has a certified limit in RHEL 
of 100TB.  It's also telling that their "Scalable File System" add-on uses 
XFS...

In the past, XFS always seemed to be the second choice of people who were 
not happy with the default:  'I use ReiserFS/Reiser4/JFS/Btrfs/Whatever 
because it does [insert narrow, specific need], but if it weren't for 
that, XFS would have been the best choice...'  It always seemed to be a 
bridesmaid for most everyone.  It seems that Red Hat is finally going to 
make it a bride...

One last thing:  everyone who uses ZFS raves about it.  But seeing as (on 
Linux) you're limited to either FUSE or out-of-tree kernel modules (of 
questionable legality:  ZFS' CDDL license is *not* GPL compatible), it's 
not my first choice for a backup server, either.

Tim Massey
 
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