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Expected RAID speeds?


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#1 SirEvan

SirEvan

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Posted 26 March 2013 - 01:20

Just looking for confirmation on my RAID config to see if it looks right. Given that the following drives are all 5900 or 7200 consumer drives, and not 15k SAS drives or SSD's, Do I have the correct configuration, or should I change something to make things faster?

Using the following:
6x Seagate ST3000DM001 3TB drives in RAID 5 (5 + 1 Hotspare)
4x Samsung HD204UI 2TB drives in RAID 10
2x WD WD20EARX 2TB drives in RAID 1
4x Supermicro 5-in-3 drive cages
Intel RES2SV240 24 port SAS expander
LSI 9260-8i RAID Controller

LSI Raid card is connected to SAS expander via 1 cable at the moment, I'm leaving the 2nd cable off as I might add an external array later if I need more storage.

the RAID 5 is used for >4GB Movies, >1GB TV Show episodes, and ISO images of OS's and apps only
the RAID 10 is used for Hyper-V VMs Only)
the RAID 1 is used for system backups from my laptop, desktop, HTPC, and netbook

I'm seeing the following performance:

6x Seagate ST3000DM001 3TB RAID5 (1MB Stripe, No RA, Write Back, Directed IO, Disk Cache Disabled):
D CDM.PNG
D atto.PNG

4x Samsung HD204UI 2TB RAID 10 array (1MB Stripe, No RA, Write Back, Directed IO, Disk Cache Disabled):
E cdm.PNG
E atto.PNG

2x WD WD20EARX 2TB RAID 1 array (32 KB Stripe,No RA, Write Back, Directed IO, Disk Cache Disabled):
f cdm.PNG
f atto.PNG


#2 +PeterUK

PeterUK

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Posted 26 March 2013 - 17:02

Looks good but I think 1MB Stripe is a bit high the way I think finding the better Stripe size is to test one HDD with ATTO where the speeds for read/write max out at a give transfer size and does not get any faster past a given transfer size and thats the smallest Stripe size you should use.

#3 OP SirEvan

SirEvan

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Posted 26 March 2013 - 17:34

Looks good but I think 1MB Stripe is a bit high the way I think finding the better Stripe size is to test one HDD with ATTO where the speeds for read/write max out at a give transfer size and does not get any faster past a given transfer size and thats the smallest Stripe size you should use.


Interesting tactic..I didn't think about doing that. I had decided to go with 1MB for the Media storage array, as most of it was either going to be sequential reading of large data (playing a 2 hour movie back), or sequential writes (storing a new movie), and then the same for the Hyper-V VM array since I figured each VHDX file would be sequentially allocated, although now that I think about it that's probably more random reads than sequential since it's going to be similar to how a computer would access a hard drive. Might rebuild the VM array with a smaller stripe size now that I think about it.

#4 OP SirEvan

SirEvan

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Posted 26 March 2013 - 23:36

Did a little more testing with 64, 128 and 256k segment sizes (256KB,512KB, 1MB Stripes) and found that 128K segment sizes yielded the best results overall for the VM drives. I was reading some articles on VMware and Hyper V that recommended 64K Segment size + 64KB cluster sizes, but this yielded a few less IOPS and transfer speed overall than 128K segment sizes (512KB stripe) and 64KB clusters. Across the board improvements, except in 8MB transfers. Overall roughly 15-80% better results :) Not bad for "Green" drives

1MB stripe on LEFT, 128KB stripe on RIGHT
E cdm.PNG E-cdm-128-64.PNG
E atto.PNG attoe-128-64.PNG