I recently configured a RAID 5 partition in Server 2008 with 4 RAID 5 disks. These disks are connected through a SATA expansion card that uses PCIe. This morning, I checked and they had finally finished synchronizing, and so I tried to do some speed tests.
Copying off the disks started pretty much fine – speeds began at > 125MB/s, then trailed down to about 70MB/s, which I found odd but not worrying. Writing TO the disks however is a completely different story. I attempted to copy some of my VM host ISOs onto the disks (~2-4 GB apiece) and this resulted in speeds of approximately 10MB/s. I tried copying both from a local disk (connected directly to the motherboard) and from another server ththe gigabit network and results were the same.
I checked the performance monitor while transferring the files and the only thing that stuck out was that my memory hard faults shot up to 6,000 per minute (spiking around 200/s) by explorer.exe. The system is running 2GB of DDR667 ECC RAM and a quad-core 2.3GHz opteron.
Is there anything I can do to fix this performance issue (buy more RAM? move the drives to a faster box?, etc) or am I just screwed so long as I stick to windows.
Best Answer
You copy them in explorer? I would say that the 6000 page faults hint on a serious issue in memory management - possibly file buffers using too much space, starting to swap. Not sure how your tempfile relates to the discs, but it could be you overloda the discs without doing real work.
Server 2008 is having this old WIndows Vista problem, IIRC, of being too aggressive with caching on disc copies - try going to a current operating system (2008 R2), that should fix it.
Software or hardware RAID 5? You know that for a large file store it makes sense to do optimized formatting as NTFS standard settings result in lots of split IO? Any reason you have so little RAM on the machine? I mean - 2gb sounds like a toy for me, so unless this is a dedicated little NAS box, what is it for? Definitely not running virtual machines ;)