RAID card limitation on older MacPro (early 2008) seems to be 2.2TB

2.2TB is the limit on every Mac Pro RAID card.

Do you need RAID 5 or a similar scheme that computes checksums on the fly?

-- if not, you don't need the Apple RAID card. Disk Utility RAID or SoftRAID will do.

Purpose of RAID5 is not really to add data security - ONLY a backup gives you data security. RAID5 is a server technology that allows a storage system to continue working through a drive failure. It also has rebuild capabilities when the drive is replaced. It is also a very complex storage method that can get corrupted making the data unavailable to anyone. Recovering a damaged RAID5 array can be impossible.

The most important consideration when you set up data storage - especially if the data is important to you, is not the type of RAID it is on, but how you back it up.

The backup is THE critical part, always. The only reason to have a hardware RAID card is to run some form of parity RAID like your RAID5. That isn't a bad thing. It works. For an individual user it usually is more critical that they understand perfectly how to administer it, RAIDs can be finicky and unforgiving of ignoring maintenance or methods of use. Also, any drives connected to a hardware RAID card are only mountable by that hardware RAID card. If something breaks it can be tough to move things to a different computer and rebuild and get the data off.

You would have to backup the data to undo the RAID. You need to backup the data anyway. Never ever count on a RAID5 to protect your data.

Rick

rnschama wrote:

If I remove the hardware RAID card, how do I configure my 4 drives into one large startup drive?

Can that be done with just Disk Utility?

Disk Utility can create a single RAID0 volume - ie: if you have 4 1TB drives then in RAID0 you get a very fast 4TB volume.

This is another setup that seldom benefits the user. It is usually faster and simpler to leave a single drive for the boot drive and then RAID a data drive. The problem with a RAID containing everything is that if you corrupt or otherwise lose the RAID your computer is down. Also, RAIDs tend to do one type of data transfer really well, depending on the type of RAID, and are slower and less efficient at other types of data transfers. OS transfers, after bootup, are lots and lots of small accesses. RAID0, and RAID5 for that matter, are very fast at big file transfers, like video or a big photo database. Those RAIDs are less efficient at multiple small transfers. And even less efficient at doing ALL the transfers on your computer - IE:doing everything from moving big data base files to small log entries on the OS to commands from the application is not the most efficient. A big RAID array is slower at a bunch of small accesses like that than a single drive is.

More efficient is to put only the data that benefits from the RAID on the RAID and put data that is best on single drives, on a single drive. Easier to backup. Especially with the OS drive, when it gets corrupted or damaged - for instance by a Apple updater (not that that would EVER happen) having it by itself and backed up to another drive means you can go to your backup and keep working. If it screws up on that big single RAID volume then everything is screwed up. Stuff happens - plan for it.

The answer to how should you set up your storage dends on what type of data and where you can advantage yourself with RAID. Your OS/Application drive is almost definitely not what you want on the RAID.

Rick

Storage Acceleration