I've got a
* Highpoint 2640x4 4-port RAID controller card
* 4 x Seagate 500GB 7,200 RPM 16MB Cache hard drives (http://www.newegg.com/Product/Product.aspx?Item=N82E16822148374) in RAID-10
And then I have
* Western Digital 2TB 7,200 RPM 64MB Cache Hard Drive (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136456)
As you know, I've had problems with I/O and IOPS for a while, so I've been playing around with testing various scenarios and trying to find the optimal solution for my situation.
I've stumbled across something that seemed rather odd to me and was wondering if there was a good explanation.
I know the Highpoint isn't a top of the line Adaptec RAID card or anything, but I've read some reviews and it was rated rather highly and is supposed to have good throughput.
I've tried two different tests:
1a. Write Speed via dd if=/dev/zero of=test.out bs=512k count=64k
1b. Read Speed via dd if=test.out of=/dev/null
2. pveperf
I'm getting:
Which to me seems like the WD Black drive is kicking the RAID's butt... I'd almost prefer to stick with a single WD drive in this case. Why is that? I know the cache on the Western Digital is larger per drive, but overall the same size... I would expect my RAID numbers to be twice what they are.
Am I missing something, or is this to be expected? Is the only way to get decent performance from RAID to go with 8+ drives?
* Highpoint 2640x4 4-port RAID controller card
* 4 x Seagate 500GB 7,200 RPM 16MB Cache hard drives (http://www.newegg.com/Product/Product.aspx?Item=N82E16822148374) in RAID-10
And then I have
* Western Digital 2TB 7,200 RPM 64MB Cache Hard Drive (http://www.newegg.com/Product/Product.aspx?Item=N82E16822136456)
As you know, I've had problems with I/O and IOPS for a while, so I've been playing around with testing various scenarios and trying to find the optimal solution for my situation.
I've stumbled across something that seemed rather odd to me and was wondering if there was a good explanation.
I know the Highpoint isn't a top of the line Adaptec RAID card or anything, but I've read some reviews and it was rated rather highly and is supposed to have good throughput.
I've tried two different tests:
1a. Write Speed via dd if=/dev/zero of=test.out bs=512k count=64k
1b. Read Speed via dd if=test.out of=/dev/null
2. pveperf
I'm getting:
Highpoint w/4 drives in RAID-10
R = 129 MB/s
W = 60 MB/s
CPU BOGOMIPS: 20042.83
REGEX/SECOND: 821144
HD SIZE: 901.01 GB (/dev/mapper/pve2-machines)
BUFFERED READS: 76.45 MB/sec
AVERAGE SEEK TIME: 16.13 ms
FSYNCS/SECOND: 343.29
DNS EXT: 93.10 ms
DNS INT: 73.25 ms
Single Western Digital BlackW = 60 MB/s
CPU BOGOMIPS: 20042.83
REGEX/SECOND: 821144
HD SIZE: 901.01 GB (/dev/mapper/pve2-machines)
BUFFERED READS: 76.45 MB/sec
AVERAGE SEEK TIME: 16.13 ms
FSYNCS/SECOND: 343.29
DNS EXT: 93.10 ms
DNS INT: 73.25 ms
R = 121 MB/s
W = 94 MB/s
CPU BOGOMIPS: 20042.83
REGEX/SECOND: 794168
HD SIZE: 1818.03 GB (/dev/mapper/pve3-backup)
BUFFERED READS: 107.96 MB/sec
AVERAGE SEEK TIME: 11.96 ms
FSYNCS/SECOND: 1628.22
DNS EXT: 84.07 ms
DNS INT: 40.56 ms
W = 94 MB/s
CPU BOGOMIPS: 20042.83
REGEX/SECOND: 794168
HD SIZE: 1818.03 GB (/dev/mapper/pve3-backup)
BUFFERED READS: 107.96 MB/sec
AVERAGE SEEK TIME: 11.96 ms
FSYNCS/SECOND: 1628.22
DNS EXT: 84.07 ms
DNS INT: 40.56 ms
Which to me seems like the WD Black drive is kicking the RAID's butt... I'd almost prefer to stick with a single WD drive in this case. Why is that? I know the cache on the Western Digital is larger per drive, but overall the same size... I would expect my RAID numbers to be twice what they are.
Am I missing something, or is this to be expected? Is the only way to get decent performance from RAID to go with 8+ drives?
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