[OpenAFS] /var/cache/openafs on btrfs

[Dale Pontius]

On 03/02/2016 01:54 AM, Fred Drueck wrote:
> Hello Everyone,
>
> According to the OpenAFS admin FAQ, it appears that the officially 
> supported file systems for the disk cache are:
>
> ext2
> ext3
> hfs (HP-UX)
> xfs (at least on IRIX 6.5)
> ufs (Solaris, ?Tru64Unix)
>
> which is clearly out of date, since there is a working implementation 
> for OS X that runs on top of HFS+
>
> For some time I've been fearlessly using both ext4 and btrfs (on 
> Linux, as you might infer) as the backing storage for my AFS client cache.
>
> I have noticed some fairly rare issues with the clients if all file/db 
> servers (in our cell the same machines) become unavailable.  The 
> '/afs' mount becomes un-accessible and attempts to access files often 
> result in very long timeouts. I've always been able to fix things by 
> somehow shutting down the client (in the worst case by physical 
> power-off and reboot into single user mode) and deleting the cache.
>
> Is there some chance that this is because I've been causing these 
> problems by using un-supported file-systems as the backing storage for 
> the client cache?
>
> I'm using fairly recent versions of the client, namely the version 
> packaged for debian-squeeze, debian-wheezy, ubuntu 14.04, and a very 
> recent release on Arch Linux.
>
> e.g.
>
> 1.6.9-2+deb8u4~bpo70+1
> Version: 1.4.12.1+dfsg-4+squeeze4
> Version: 1.6.7-1ubuntu1.
> openafs 1.6.14.1-1
>
> For the most part, though, I haven't had many issues.  Does anyone 
> know any updated info on what the supported client filesystems are?
>
> Thanks!
> -Fred
>
I've been using an ext4 partition for my cache for years now.  There are 
several additional optimizations that can be done, but the only one I 
remember at the moment is to create the filesystem without a journal.  
Because ext4 natively allocates extents, these can directly map to cache 
chunks.

I've been happy.

Dale Pontius

-- 
Dale Pontius
Senior Engineer
IBM Corporation
Phone: (802) 769-6850
Tie-Line: 446-6850
email: pontius@us.ibm.com

This e-mail and its attachments, if any, may contain confidential and privileged material for the sole use of the intended recipient. Any review, use, distribution or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive for the recipient), please contact the sender by reply e-mail and delete all copies of this message from your system without copying it and notify sender of the misdirection by reply e-mail.