On Thu, Jul 26, 2012 at 11:44:05PM -0500, Robert Nesius wrote: > With iSCSI, where is the filesystem management overhead?Is the > filesystem overhead is on the client side with the server just receiving > low-level I/O operations that go straight to disk, whereas with CIFS the > server is having to handle mapping the I/O from the filesystem layer > through to hardware layer, causing it to be slower on it's responses > (ACKS)? I've never worked with it myself... just curious. Yes, that's how it works. However, I am measuring the performance of the system composed of the two machines (plus the switch) and iSCSI shows twice the performance of CIFS. Somebody has to do the filesystem dirty work, be it on the client or on the server. I could see where you have a workload that you spread across two sub-systems and if one of them reaches capacity, that limits the throughput of the entire system (some variation of Amdahl's law). But both boxes are very powerful (3.3GHz 6-core for workstation, 2.8GHz 4-core for server) and completely idle that neither is the bottleneck. I'm writing a 11GB file, and the server has 16GB of RAM. The CIFS results were so bad, I was concerned there was a problem with the hardware. It just occurred me two days ago that I could flip things around, use iSCSI and test the system performance in a different way. Cheers, florin -- Beware of software written by optimists! -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 198 bytes Desc: Digital signature URL: <http://mailman.mn-linux.org/pipermail/tclug-list/attachments/20120727/c6ea8ff8/attachment.pgp>