[OpenAFS] Re: Linux ext4 vicep and cache support?

Dale Pontius pontius@btv.ibm.com
Wed, 25 Jan 2012 15:56:01 -0500

Would it make sense when using ext4 as a client cache to turn the 
journal off, for a little bit more performance?
I'm also wondering if some of the afs cache tunables could also be 
translated into mkfs.ext4 tunables, for a closer fit.  (afs cache 
chunksize vs ext4 extents, etc)

Dale Pontius
On 01/25/2012 02:21 PM, John W. Sopko Jr. wrote:
> Thanks, all. It has been at least a year since we tried
> running the cache on ext4 with 1.4.12 client and I have
> never tried on a fileserver /vicep partition.
> Our current AFS file servers are redhat 5.7 ext3. When we
> get new servers they will be redhat 6.x and ext4.
> When we upgrade clients to 1.6 I will try ext4 cache.
> Thanks.
> Andrew Deason wrote, On 1/25/2012 11:05 AM:
>> On Wed, 25 Jan 2012 09:38:30 -0500
>> "John W. Sopko Jr."<sopko@cs.unc.edu>  wrote:
>>> Is it safe to use ext4 for /vicep partitions?
>>> The install docs do not mention file system type
>>> requirements.
>> Filesystem doesn't matter for /vicep, for the most part. You can use any
>> fs as long as we get 'normal' unix-y features with it (owner, group,
>> access modes, etc; I assume just saying "POSIX" is enough). The server
>> processes generally don't do anything special with the files in there,
>> except for setting the owner, group, and mode bits to "strange" things.
>>> In the past we had issues with ext4 as a client cache partitions and
>>> continue to use ext3, has anything changed?
>> 1.6 clients use a different mechanism for accessing the cache, and
>> should no longer be limited to particular file systems. All versions of
>> 1.4 I believe still have the same cache fs restrictions, which limits
>> you to ext2/3.
>> That is, assuming Linux 2.6+. Nearly all Linux-specific changes to 1.6
>> clients don't apply to Linux 2.4 and earlier.

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

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