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Mac Pro Software RAID 1 Performance Issues.

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Gabe Hatfield
Mac Pro Software RAID 1 Performance Issues.
on Oct 21, 2010 at 7:59:41 pm

I posted this over in Apple OS X, but it may be more appropriate here...

I've just set up two new Mac Pro 2x2.93 Ghz 6-Core machines with (4) 2TB Sata drives in each. (the drives are different models in each computer, but the 4 drives within each computer are the same). I've set the drives up as 2 separate RAID 1 sets. Bays 1 and 3 are my boot drive as one RAID 1 set, and bays 2 and 4 are a second RAID 1 volume.

I'm getting curious performance issues on the non-boot drive RAID set on both machines. If I run an AJA system test on the boot drive, I read/writes around 130Mb/sec. The same test run on the other RAID volume yields 30-40Mb/sec, as well as a substantial lag before the drives begin to access.

Any ideas why this is happening. Can you set up two separate RAID 1 volumes using disk utility?

Thanks,

Gabe

Hatfield Post/Production, Inc.
819 W. Superior
Chicago, IL 60622
312-226-3200
312-226-3211
http://www.hatpost.com


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Bob Zelin
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 22, 2010 at 5:06:30 pm

you have a bad drive. A single SATA drive from any company will do over 60 - 70 MB/sec all by itself. You have to test the drives one at a time, (killing your RAID 1 group) to see which drive is bad.
Modern SATA drives will do between 80 - 100MB/sec all by themselves.

Bob Zelin



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Terry Mikkelsen
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 22, 2010 at 5:23:33 pm

But he says this is happening on TWO different computers. Anything is possible, but I find it hard to believe that two drives are bad. If they are, go run and buy some lotto tickets too.

Tech-T Productions
http://www.technical-t.com


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Chad Brewer
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 24, 2010 at 1:28:39 am

Hi Gabe.
Our broadcast video facility is 3 blocks from your office and we provide services to just about every post-house, big and small, in Chicago and the Mid-west. You guys should swing by and check us out.
Anyway, when we haven't been building external RAIDS for our MacPro's, we've had great performance with internal RAIDS in a different configuration. Try not involving the boot drive in a RAID. RAID 0 the other 3 drives in the MacPro for 6TB. We use 2TB Hitachi drives for this and have read/write speeds of 400mb/sec until the RAIDS don't have enough overhead. At that time or even before if something needs to be backed up, we'll just transfer whatever we need to save via an eSATA dock to other drives overnight or when there is downtime.
We've pushed countless hours of 10-bit HD and even dual-link 4:4:4 with this configuration. You just need to backup and sometimes rebuild the RAID, but it can be fast if you have good drives.
If you truly need longer term redundancy instead of fast speeds now and occasional backup/re-RAID, you'll have to spend more money for the high end external arrays.

Chad Brewer
Senior Tape Operator/Engineer
TeleVersions


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Gabe Hatfield
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 25, 2010 at 4:05:20 pm

Thanks for the advice Chad.

I've set the systems up this way to have internal data redundancy for our system disk and our project file disk, so I don't need crazy speeds from these drives. We use an external Sonnet RAID set at RAID 5 and connected via eSATA for our media files.

I want to have the the internal drives RAID 1 so that we have an instant backup for all of our non-video media data.

-Gabe

Hatfield Post/Production, Inc.
819 W. Superior
Chicago, IL 60622
312-226-3200
312-226-3211
http://www.hatpost.com


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Walter Soyka
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 27, 2010 at 2:14:50 am

[Gabe Hatfield] "I want to have the the internal drives RAID 1 so that we have an instant backup for all of our non-video media data."

RAID is not backup.

RAID 1 will protect you from failure of one of the drives in your set of two, but that's it. It will not protect you from a controller failure, a filesystem problem, an electrical problem, fire, flood, theft, or accidental deletion.

If you want an instant backup of your project files, use Time Machine.

Walter Soyka
Principal & Designer at Keen Live
Motion Graphics, Widescreen Events, Presentation Design, and Consulting
RenderBreak Blog - What I'm thinking when my workstation's thinking
Creative Cow Forum Host: Live & Stage Events


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Bob Zelin
Re: Mac Pro Software RAID 1 Performance Issues.
on Oct 27, 2010 at 6:38:51 pm

Walter is correct. RAID is not backup. RAID protects against failure, but the only way to protect against catostrophic failure is redundant backup (additional drives, LTO, you know - SPEND MORE MONEY).

Bob Zelin



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Jeff Cummings
Re: Mac Pro Software RAID 1 Performance Issues.
on Mar 30, 2011 at 12:10:55 am

Hey Chad-

You are getting 400MB/s using a software internal raid or do you guys use a raid controller? I just set up my MacPro1,1 with a 500GB system drive, a 500GB data drive and 2 Hitachi 2TB drives striped via Apple software raid. I am getting 300MB/s from the software raid with the drives at 10% capacity.

Thanks,
Jeff


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