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RAID speeds
I have 2 x 4 SATA Raid arrays striped with Softraid, which is hooked up to my Dual 2.0 G5… I wanted to find out what my read and write speeds were for an upcoming online, so I ran Kona testchecker utility to check the read/write speeds of my drives.
On one of my 4 drive arrays, I got speeds averaging around 210 Mb/s for both read and write… but on my other set I only got 78Mb/s read and 200 Mb/s for write…
Any ideas what is making my read speed so low?
They are all seagate 300gb drives, and actually the slower set of the drives has 710GB remaining free space (out of 1.2TB) and the faster has only 310GB left…
I’m stumped.
Morgster
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5 Replies
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[morgster] “Any ideas what is making my read speed so low?”
Your SATA card maybe? We were running two CalDigit arrays on one of their SATA cards and had zero speed dropoffs on the two units.
What happens if you only have one SATA array connected at a time? Do they give you full speed each?
Walter Biscardi, Jr.
https://www.biscardicreative.com
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easy. Take your “bad” RAID – the one that is working at 78mb/sec read. Delete the RAID group in Apple Disk Utility. Now, initialize each drive (that’s right – the 4 seperate drives) – and TEST EACH ONE. You should get about 68mb/sec PER DRIVE. One will probably fail, or hang up during your testing with AJA Kona System Test – this is your bad drive.
If you can’t do this test, because you have media on this array, and can’t delete the media – I bet your drive array is FULL. Full drive arrays don’t work very well.
Bob Zelin
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Actually the RAID is not full… it’s running with over 650GB left on the drives (out of 1.2TB)… and I had it the wrong way around, it’s my write speed that’s around 70MB/s and the read that’s at 210 MB/s… not sure if this makes any difference…
I’ll try to offload footage on that drive and go from there.
Cheers
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If I have only one SATA RAID connected, the write speeds are still down to 78MB/s and read is around 209.9MB/s… does that mean it isn’t my card…
Yesterday I wrote that it was the read speeds that were slow, my mistake… it’s the write speeds that are around 78MB/s… the read speeds are fine at over 200mb/s…
What d’ya think?
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Bob…
I did as you told me and re-initialized the disks separately… here is how my 4 drives read
1 – 61.6 mb/s write, 64 mb/s read
2 – 56.4 mb/s write, 56 mb/s read
3 – 57.3 mb/s write, 58.2 mb/s read
4 – 65.6 mb/s write, 66.4 mb/s readDoes that mean drives 2-3 are pulling me down? that shouldn’t be the case really should it? none of the drives are hanging up, so they are still all good…
I’m puzzled… can you help?
SM
I am using AJA Kona System test utility to do this… is it reliable?
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