Raid 1 with two external drives

Question

Hi Everyone,
I've been searching for some answers on this and havent quite found what ive been looking for so i figured id just ask. I have two identical 1tb g-drives daisy chained and hooked up to my imac via Firewire 800. I want to make one of the drives raid 1 to mirror all the information on the other. What is the best way to go about doing this?
I was also wondering would it be better just to have time machine do backups of one drive onto the other? any advantages/disadvantages to either method?
Thanks in advance everyone!
Cheers,
Scott

Answer 1

scotty morrison wrote:
These drives will be used to store Masters and dailies from photo and video shoots and well as the final edits from those shoots, so id qualify them as "mission critical".
Instead of "making" your own RAID1 array, you may want to investigate some "turn-key" RAID solutions. For example [this one at Macsales|http://eshop.macsales.com/shop/Mercury-EliteAL-Pro-RAID]. (That's just one RAID1 turn-key unit that Macsales has.)
Since you mention video, perhaps even consider RAID5 for more capacity, or RAID10 pr RAID0+1 for higher speeds. RAID0 would be good for the edits "scratch space", but not for any "real" storage. Thus the use of RAID10 or 0+1. (If you really want to get the max performance, do some research on the differences between 10 & 0+1.)
...Im now thinking however that i should have my masters in raid1 and on separate drives have my live edits being backed up by time machine as they change. Would this be a good thing to do?
Again, RAID1 is not a backup, so regardless of where you have the "masters", they should be backed up. With the backup, you can then recover from a loss of a drive, it will just be a little more time to get running again compared to RAID1. Thus the "need" for RAID1 is debatable for the masters and final edits, etc.
Also realize that RAID1 & RAID5 generally have slower performance than an individual drive (or RAID0) due to the overhead of writing the mirror or parity info. In many "workstations", they have a individual drive to boot from, then a RAID0 array for the editing "scratch space", and the final version of the file on some other storage. (i.e.: RAID5 SAN.)
Be careful with reliance on Time Machine for backups. Time Machine is good, but sometimes Time Machine can't backup files that are in use. (e.g.: [iPhoto|http://support.apple.com/kb/HT4116].) This is true of most backup systems unless you get some really expensive software so for something you're considering "mission critical" like these video files, I'd be looking at an additional backup system. (Even something as lowly as manually copying files to an external hard drive or an Automator workflow.)
To give another perspective: RAID1 if you absolutely can't have this system down for even one second. Which means your boot drive needs RAID1. Your "scratch space" on RAID0 or a SSD, since you want speed and can deal with the loss of a drive. Your "masters" & "final edits", you need to consider _+long term+_ storage. (a.k.a.: archiving.) The largest hard drives currently are 3TB. Being video, I'm going to guess you'll out grow this quickly. With RAID1, you'd be "stuck" at 3TB until larger hard drives come out...and then you've have to buy two of them...then be "stuck" again. So IMHO you should be looking at a RAID5 system that can grow. They can be "slower" RAID5 since you're looking at long term storage rather than max performance like the scratch disks. (If you need a little more performance, then RAID10, but you'd be sacrificing capacity.) For example, the 8 or 16 drive Drobo. Start with 2 or 3 drives now, then add more drives as needed. Drobo's of this capacity aren't cheap, but if they are as "mission critical" as you think they are, then a Drobo or similar is probably a worthwhile investment. But really, it appears to me that a proper backup procedure of your masters/final edits would be sufficient. RAID1 then is just icing-on-the-cake, albeit, very good icing.