break the stripe and check disk speeds individually. Also, open the side panel and touch the drives, one by one, strong vibration means lower speed.
Hitachi drives have, in my experience, the highest failure rate - except when they are enterprise grade, so I would not be surprised if you've got a lemon out of 4.
And you are right, an empty, freshly formatted 3way stripe should sustain 300-350MBps. Both read and write.
cheers,
BG
www.finale.tv
--- On Fri, 12/28/12, John Moore <bigfish@pacbell.net> wrote:
From: John Moore <bigfish@pacbell.net>
Subject: [Avid-L2] 3 way internal stripped raid on MacPro Speed?
To: "Avid L2" <Avid-L2@yahoogroups.com>
Date: Friday, December 28, 2012, 1:33 AM
I've put 4 4TB Hitachi Deskstar 7200 RPM drives in my new 12 core MacPro. Using one drive as startup and three for the raid strip made with disk utility. AJA system test yields 153.2MB/s Write and 240.4MB/s Read. AJA data calc shows 1920x1080 1080i 10 bit YUV data rate at 165.72 MBytes/sec. If both these are accurate wouldn't that mean I would have a potential bottleneck trying to capture uncompressed 1:1 in Avid? I was also surprised to see the AJA disk whack speed test came out around 100 MB/s write and 150MB/s read on the single startup drive. I would think the three way strip should be ball park 3 times faster. Is this lower than expected performance a product of the mac disk utility software raid? Am I oversimplifying the process thinking internal drives should be faster than some external connected storage solutions? I've been told internally the macpro is sata 2 not 3 but in googleing sata 2 can yield 300MB/s. Clearly I'm
not
fully clear on the data balistics of the MacPro internal drives. I have had decent performance with a 2 drive strip with DNX 220 on a MacPro SNDX 4.x. Never tried uncompressed on that config. Curious what others have done. I set the raid block size to 256K after reading a tutorial on how to set up the raid. Does that seem like an optimal block size? TIA
John Moore
Barking Trout Productions
Studio City, CA
bigfish@pacbell.net
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