SLOW raid1 RS2BL080 server

[clsGrinder]

getting mega slow mirror'd array performance from RS2BL080 8 port intel raid controller 512 MB cache. Drives are basic Seagate Enterprise Class SATA.

21 MB/s (36.9ms) avg

data array on same controller RAID5 getting 253 MB/s(10 ms avg).

I'm not expecting the same performance from the RAID 1, but I am expecting to hit at least 60 so the server can reboot itself in under an hour!

OS SBS2011, dual Xeon E5xxx series, 24GB ram, yadda yadda

thx

 

[Concentric]

What are you using to give you those performance numbers?
Can you take this server offline and run some tests or is it currently in production?
What stripe size is the array using?

If you can, test the drives individually, both on the controller and connected to something else (maybe the onboard SATA).
Also, can you see what mode the card is in - RAID or HBA (boot into it's setup utility)? See: http://www.servethehome.com/lsi-sas-2108-raid-controller-information-listing/

 

[clsGrinder]

HDD tune (free)
It's in production... it's starting to smell like it's SBS 2011 overhead more than anything else.. it's a pig!
stripe size is 256k

if i have a chance in the next week I will try and slave this array under a quick and dirty win7 install and see what my numbers are like under the same benchmarking software?

 

[Mr.Pernod]

sounds like the RAID5 is in wite-back mode (using the cache on the controller), but the RAID1 is in write-through mode and has the on-disk cache disabled.

 

[clsGrinder]

both are write through (no BBU).

 

[Mr.Pernod]

if the server is on a UPS you could test the RAID1 in an "Always write back (independent of BBU state)" mode and see if it is worth investing $180 in a BBU.