Internal raid 1 in macpro: good idea?

Hey wizards-

Happy New Year!

I want to add storage and redundancy to my mac pro. The plan is to buy 2 seagate 500gb internal drives and "raid 1" them. I have read that a software raid is not as good as a hardware raid, but for about $200 and no dealing with external FW drives/enclosures/ports/esata cables, etc. it seems like a good way to go. Are there issues w/ software raids during system software updates, 10.4 to 10.5 upgrades, etc? I can deal with little hassles, but I dont want to sacrifice reliability.

I am also thinking of going Raid 1 with my system drive, either using the 4th internal slot on the macpro or using and external FW drive as a mirror. ( I may need to use other than mac software to Raid an internal and an external together- haven't verified)


Any thought/suggestions/recommendations/chastisements?


Thanks all-

Paul

""Are there issues w/ software raids during system software updates, 10.4 to 10.5 upgrades, etc? I can deal with little hassles, but I dont want to sacrifice reliability."

RAID 1 is a safety to copying data to two identical disks at the same time. It slows down the transfer speed dramatically, however. Using a software RAID also has peril as it can be taken apart by an OS update or upgrade. The safety is that even if the RAID stops working, the original data is on both disks up until the point the RAID stopped working.

""I am also thinking of going Raid 1 with my system drive, either using the 4th internal slot on the macpro or using and external FW drive as a mirror""

IT is not a good idea to use RAID 1 on a boot disk. RAID 0 works but there is a danger of loosing everything. Using RAID 1 dramatically slows down the file transfers as the operating system has to push out two copies of each change to a disk.

A much more useful approach to the boot drive might be Leopard's Time Machine. Attaching an external Firewire drive and starting up TimeMachine will build a RAID 1 scenario and make changes to the external drive as they change without hampering the operation of the boot disk

Thanks John-

so I get it for the boot drive, Time machine when I make the Leopard switch.

On the data drives though, most of the things i read online did not actually have much slow down in RAID 1. I was searching a lot though and may have been reading about hardware RAID1's at the time. If there is NOT much actual slow down and the only risk to a software raid is that I may have to "reset" the raid after a software update ( data intact), it still seems like a good idea. Am I grasping at ( inexpensive) straws?


Paul

Paul,

There are different levels of safety in computer disks. Most disk drives really don't fail very often. That's not to say that they don't fail at all, but the Mean Time to Failure figures on almost any disk drive are into the millions of cycles.

RAID 1 is a way of guaranteeing solid data transfers, even if one drive fails. It requires two drives and only one level of storage. RAID 5 sums the total capacity of at least 3 drives and proportions some of each to hold the repair code (in case one of the three drives fails)

The most secure and costly RAID is 0+1 (or RAID 10) which stripes all disks with RAID 0 (fastest RAID) and a separate set of disks with another RAID 0 which are then striped as RAID 1. Where a RAID 5 may be able to use 3 disks, a RAID 0+1 uses double the number of disk drives and controller ports.

Hey John and all-

Sorry if I wasnt clear on my 2nd post, but I was just wondering if there REALLY is much slow down w/ an internal 2-disk RAID 1 ( as opposed to single disks). I will probably be doing HDV/DV projects mainly. If the slow down is really minor, then it seems like an internal raid 1 would be an easy, inexpensive "more safe than a single drive" storage space.

(I do understand the redundancy/non-redundancy options with the different RAID levels, or at least the diff between RAID 0 and RAID 1, which would be my options in this case)

Again thanks for your responses
Paul