On 06/27/2012 05:04 AM, Boris Epstein wrote:

Hello listmates,

Has anybody attempted to run an XFS in a file mounted via -o loop? The file size is about 20 TB and it resides in a larger XFS filesystem residing on a disk. That filesystem's size is about 25 TB. What sort of degradation should one expect under that sort of scenario?

The reason I am asking is that I am trying to run a MooseFS chunkserver in that filesystem-in-a-file and looks like I am getting some pretty bad delays.

Why would you do something like this? MooseFS depends on parallelism which means you want many smaller chunkservers instead of a few big ones. Also MooseFS requires some initial roundtrips when accessing files which makes it unsuitable for storing/accessing lots of small files. Basically you trade in latency for throughput (thanks to parallelism) which makes MooseFS a candidate for storing and transfering large files. What are you trying to accomplish and what exactly do you mean by "pretty bad delays"?

Regards, Dennis