B2D Performance.

[nicktf]

We have an MSL4048 LT0 3 connected through a fibre infrastructure to a DL380g5 and to an MSA1000. THe servers, switches and LT0s run at 4Gb and the MSA1000 is a 2GB device.

(1) When we back up from network direct to tape, we get a throughput of about 6Gb/min
(2) Backing up a B2D file (chosen as a large chunk of uncompressible data) from the MSA1000 to tape slows down to 4.5Gb/min
(3) Backing up the network data to a B2D file (10Gb and already preallocated) data rate slows to *1Gb/m*
(4) Duplicating the B2D file to tape gives a throughput of about 1.8Gb

The Server and MSA were isolated during the benchmarking so there was no contention.

(1) Indicates that there is no bottleneck on the Fibre/Network
(2) Indicates the MSA is capable of reading up to 4.5Gb/m
(3) Is the poor performance purely from RAID 5 (cache is 50%read/50%write)???
(4) If the MSA can read at 4.5Gb/m why does the duplicate only run at 1.8Gb/m

Cheers

Nick

[Hywel_Mallett]

Have you checked the partition your B2D folder is on for fragmentation? It can get very bad with B2D files. Maybe it's not that, but it's worth checking.

[nicktf]

Thanks -  it's a shiny, new, dedicated partition (64k clusters). Pre-allocation seems to work, and there is no fragmentation at all on the disk.

I've got a slight performance increase by setting compression from Hardware or none to Software. I've also taken scheduling steps to ensure that while data is being written to disk no reads (such as another job writing to tape) are occurring. Other than that I'm drawing a complete blank - I can't see why I can get a better performance from an identical MSA attached to a remote server than one which is fibre attached to the Backup server.

I've also changed my CPS backups so that I backup the target server, rather than the CPS data on the Backup server, as the throughput is 2900Mb/s against 1150Mb/s

The fibre ports are barely breathing - around 0.4-0.5 Gb/sec








Message Edited by nicktf on 11-30-2007 08:17 AM

[Bruce_Bosco]

Any update on slow B2D performance? We have the same issue.

[CraigV]

Hi Bruce,

I'd suggest opening a new forum query...this has been dead for over a year.