Striped RAID on Mac Pro

[claskin]

I am trying to setup a striped RAID on my Mac Pro. I am attempting to do this using my main drive and the second internal drive. However, the option is grayed out on the disk utility menu. Is this not possible using the main drive or am I missing something?
Any comments will be appreciated.
Carl

[Jack Flesher]

I am trying to setup a striped RAID on my Mac Pro. I am attempting to do this using my main drive and the second internal drive. However, the option is grayed out on the disk utility menu. Is this not possible using the main drive or am I missing something?
Any comments will be appreciated.
Carl

What drive is your OS currently running from?  IOW you cannot drag a running OS partition into the RAID dialog as it must be erased first, so you need to have copied your OS to another drive, an external is fine.

The proper procedure is then to reboot off the back-up OS drive then partition your disks -- identical disks partitioned identically -- then drag the matching partitions from each drive into the RAID dialog, giving a name to that particular stripe, repeating for the remaining partitions if any.  You can then copy your OS back onto the new faster stripe and reboot from it.

Cheers,

[Lab Magician]

Carl - one thing to remember with using the software raid is that all the RAIDing is done by the OS and processors.  So if you heavily load the processors, you can impact the RAID speed.  Also if you have a crash or a power loss you can get disk corruption because the data will not necessarily be written to disk immediately.  I suggest that you keep good backups of all important data on those drives and if you do have a crash or power loss, then the very first thing you do is boot from the Install DVD and run Disk Utility Verify Disk against the drives to check for any damage.  If some is reported, then try DU Disk Repair, but because the file structure on  individual disks can be OK, but the RAID directory corrupt, be prepared to lose everything and have to reload.  If you're using Time Machine then that should be an easier task.

Personally, I wouldn't use software RAID.

Baz

[claskin]

Jack
A great help. I used a RAID with my last MacPro but for the life of me I cannot recall going through these gyrations. Your method makes sense and I want to thank you for taking the time to spell it out.
Regards
Carl

What drive is your OS currently running from?  IOW you cannot drag a running OS partition into the RAID dialog as it must be erased first, so you need to have copied your OS to another drive, an external is fine.

The proper procedure is then to reboot off the back-up OS drive then partition your disks -- identical disks partitioned identically -- then drag the matching partitions from each drive into the RAID dialog, giving a name to that particular stripe, repeating for the remaining partitions if any.  You can then copy your OS back onto the new faster stripe and reboot from it.

Cheers,

[claskin]

Baz
Much appreciated especially your last recommendation. As I mentioned in my reply to Jack, I used a soft RAID with my last MacPro without a problem. However, I was always concerned regarding a crash or power issue. I cannot justify a hardware RAID so I may just stick with what I have and live without RAID.
Thank you again.
Regards
Carl

Carl - one thing to remember with using the software raid is that all the RAIDing is done by the OS and processors.  So if you heavily load the processors, you can impact the RAID speed.  Also if you have a crash or a power loss you can get disk corruption because the data will not necessarily be written to disk immediately.  I suggest that you keep good backups of all important data on those drives and if you do have a crash or power loss, then the very first thing you do is boot from the Install DVD and run Disk Utility Verify Disk against the drives to check for any damage.  If some is reported, then try DU Disk Repair, but because the file structure on  individual disks can be OK, but the RAID directory corrupt, be prepared to lose everything and have to reload.  If you're using Time Machine then that should be an easier task.

Personally, I wouldn't use software RAID.

Baz

[Lab Magician]

Carl - What do you want to use the RAID for? If it's fast PS scratch and you have plenty of RAM you can use some of that for fast scratch by setting up a RAM drive. If you can afford a third internal HDD, even one that's small capacity, and dedicate it for scratch then that will also be faster.

If you make sure you have very good backups (one thing I really hate is loosing data - particularly stuff that I've worked on long and hard) and since you're aware of the problem areas because you've used it before, then why not set up software RAID and see if it speeds up things for you. Just don't keep all your Gigs in one basket - if you'll excuse the pun  

It mainly depends on what you're using the Mac Pro for.

Baz

[BernardLanguillier]

I cannot justify a hardware RAID so I may just stick with what I have and live without RAID.

And, believe me, you wouldn't want to use Apple's hardware RAID card anyway even if you could afford it.

Based on my first hand experience, I wouldn't put it back in my system even if they paid me 1000 US$ to do so, and I mean that.

Cheers,
Bernard