Re: [Moosefs-users] Best FileSystem for chunkers.

[Atom P. <ap...@di...>]

On 05/17/2012 12:44 PM, Steve Wilson wrote:
> On 05/17/2012 03:26 PM, Atom Powers wrote:
>> * Compression, 1.16x in my environment
> I don't know if 1.16x would give me much improvement in performance.
> I typically see about 1.4x on my ZFS backup servers which made me
> think that this reduction in disk I/O could result in improved
> overall performance for MooseFS.

Not for performance, for disk efficiency. Ostensibly those 64MiB chunks
won't always use 64MiB with compression on, especially for smaller 
files. Most of my files in the Moose cluster are quite large; I get 
1.86x compression on the mail store, which I'm considering moving to 
MooseFS.

>> Bad: * high RAM requirement
> Is the high RAM due to using raidz{2-3}?  I was thinking of making
> each disk a separate ZFS volume and then letting MooseFS combine the
> disks into an MFS volume (i.e., no raidz).  I realize that greater
> performance could be achieved by striping across disks in the chunk
> servers but I'm willing to trade off that performance gain for
> higher redundancy (in the case of using simple striping) and/or
> greater capacity (in the case of using raidz, raidz2, or raidz3).

ZFS does a lot of caching in RAM. My chunk servers use hardware RAID,
not raidz, and still use several hundred MiB of RAM.

Personally, I would prefer to use raidz for muliple disks over MooseFS,
because managing individual disks and disk failures should be much
better. For example, to minimize the amount of re-balancing MooseFS
needs to do; not to mention the possible performance benefit. But I can
think of no reason why you couldn't do a combination of both.

-- 
--
Perfection is just a word I use occasionally with mustard.
--Atom Powers--
Director of IT
DigiPen Institute of Technology
+1 (425) 895-4443