raid 5 or raid 10

[NickS]

Hello,
What is faster, a 7 drive Raid 5 or a 6 drive Raid 10?

I need to upgrade an existing 3 drive Raid 5 (system bottleneck). The array will house a heavy load SQL DB.

The server is running on an IBM ServeRaid 4MX attached to an external EXP300, half the bay will run the new Raid 5 or Raid 10 and the other half a Raid 5 and 2 Raid 1.

Thanks
Nick

 

[technome]

Go to this forum link, then search on user name FemmeT, this guy know his stuff, he has tested many raid cards and has posted statistics, performance charts of many raid adapters.
Just for you info, I just spent 2 1/2 days testing raid 5 setups on a dual Opteron 246, 5 and 6 drive scsi15k.. little difference in speed after 5 drives on a dual channel Lsilogic u320-2x adapter. Reads are about 270 Meg/s, writes are 100 m/sec average on raid 5. In the past, I set up a large raid 10 array on a lsilogic u320-2 adapter.. performance gain was so minimal vs the lost capacity of raid 10, I reconfigured the array to raid 5..from my recollection, raid 10 was under 5% faster. I also found with this last test period..placing the pagefile or the OS on a separate raid 1 ( differnt spindle) from the data array, does not help throughput, actually my test show it is much slower eg OS on a 2 drive raid 1, raid 5 (5) drives, for data... or the OS on raid 5, pagefile etc on a raid1.

http://forums.2cpu.com/forumdisplay.php?s=6cd42f8c520a21fcb6b68e46bdb7560f&forumid=26

 

[catorze]

Nick:
Faster to do what? Read or write? How are you determining the RAID 5 Logical Drive is the bottleneck? How many channels of the Controller are you using? Based on your described configuration, it sounds like HDDs are expendable, and your RAID configuration perhaps more complicated than necessary. You can certainly improve performance in a RAID 5 configuration by having more heads (HDDs), but the bottleneck may be that you are overtaxing the RAID Controller due to your current configuration. A couple of solutions are:
1. Simplify your RAID configuration to maximize the performance of your existing hardware.

2. Upgrade your RAID controller to one with a larger cache - the 4Mx has a 64MB cache. By comparison, the 4H/5i/6i have 128MB caches, and a 6M with 256MB cache is available.