understanding RAID...which is best for me?

[Keebler]

Hi,

I"m about to buy a mac pro very soon...trying to hold out, but projects are piling

in doing my research and watching HD prices go down, I should create a RAID system. I was thinking of 2 x 750 GB HDs.

i checked out the RAID at wikepedia, but despite not being the dumbest guy in the world, i'm not the smartest

here's what i want to do:

when i transfer video/audio to 1 HD, i would like it to automatically be backed up/copied to the 2nd drive. is this the 'mirrored' RAID?

Cheers,
Keebler

 

[bigbossbmb]

Yes you want a mirrored RAID. It is called RAID1.

 

[killmoms]

The only reason to use RAID for video is to speed up write AND read times, by using striped RAID 0. This also halves your data security—if one drive fails, you lose EVERYTHING. This is why you should use RAIDed volumes only for capture/editing on current projects, and backup regularly.

Mirrored RAID (RAID 1) is more about data security (although it can increase read speeds), but if you're needing more bandwidth on the acquisition end then you need faster write speeds as well, which RAID 1 does not provide.

 

[Nuc]

I'm going to be getting a dual enclosure soon. The drive supports Raid 0 and well as individual drives. Which do you think is best, Raid 0 or keeping two individual drives? I'm going to be getting 2 SATA drives from Seagate. I'll be mostly using this for video. So what do you guys think?

Didn't mean to highjack the thread.

Nuc

 

[pdpfilms]

I'm going to be getting a dual enclosure soon. The drive supports Raid 0 and well as individual drives. Which do you think is best, Raid 0 or keeping two individual drives? I'm going to be getting 2 SATA drives from Seagate. I'll be mostly using this for video. So what do you guys think?

Didn't mean to highjack the thread.

Nuc

Funny you ask, Nuc...

What I've been doing is keeping them as individual drives, and using Backup to do backups every 24hrs. This helps in multiple ways:

-Redundant, Full backups.

-Striped RAID setups copy instantaneously. Thus, if you accidentally delete your video, the other drive does the same. Backing up every 24hrs gives you a buffer period: if this happens, restore your backed up copy, and you're good to go. The absolute most you'll lose if a drive fails is 24hrs of work.

-Leopard: Time Machine is coming, and I'm sure it'll support multiple drives. I'm not positive, but doesnt changing RAID formats (from striped to individual or vice versa) require formatting the drives? Either way, it will be easy to convert to Time Machine with individual drives.

Just my thoughts. P.S..... I still have one of those puppies for sale for $300.

EDIT: Oh, NM. Just saw you were linking to the enclosure alone.

 

[Keebler]

The only reason to use RAID for video is to speed up write AND read times, by using striped RAID 0. This also halves your data security—if one drive fails, you lose EVERYTHING. This is why you should use RAIDed volumes only for capture/editing on current projects, and backup regularly.

Mirrored RAID (RAID 1) is more about data security (although it can increase read speeds), but if you're needing more bandwidth on the acquisition end then you need faster write speeds as well, which RAID 1 does not provide.

KM...by increasing bandwidth, do you mean that capturing video will be slower? my main goal would be to load a pile of video (let's say 10 hours) for editing and dvd production. would i experience slower working speeds? I just want my footage copied so i don't lose 10 hours of transfer time and more importantly, 10 hours worth of wear and tear on my clients tape and my equipment.

Cheers,
Keebler

 

[seniorstinky]

A quick overview of RAID:

RAID 0 (striping) - This is actually not RAID as the Redundant part of the name is missing (RAID=Redundant Array of Inexpensive/Independent Disks). You write across all your drives and as a poster already stated, if you lose one drive, you've lost it all. Requires at least 2 drives.

RAID 1 (mirroring) - This is the slowest of real RAID technology. You are writing the same data to multiple disks (obviously even numbered). Requires at least 2 drives. You lose half of your drives for parity (ie. If you have 4 disks, you only have effectively 2 disks worth of drive space... if you have 10 disks, you only effectively have 5 disks worth of drive space.

RAID 5 (striping with parity) - This is the same as RAID 0 except that you have a parity bit for everything that is written across the stripe. What that means is that if you lose a drive, the parity will allow you to continue to run w/o losing data until the drive is replaced. Lose two in your array and you are toast however. Requires at least 3 disks. You lose one disk for parity (ie. If you have 4 disks, you only have 3 disks worth of space for data... if you have 10 disks, you only have 9 disks worth of space for data.

There are other RAID implementations but by far these are the most popular. The fastest of the above, RAID 0. It, however, is the most susceptible to data loss.

My recommendation is RAID 5 as you get a performance boost above and beyond one single disk and you get insurance for drive failure.

Also, remember that spindle speed is a huge deal. The faster the RPM of the disk, the faster the read/write.

 

[seniorstinky]

-Leopard: Time Machine is coming, and I'm sure it'll support multiple drives. I'm not positive, but doesnt changing RAID formats (from striped to individual or vice versa) require formatting the drives? Either way, it will be easy to convert to Time Machine with individual drives.

You can't "change" RAID formats without recreating the data. Some systems will allow you to expand an existing format (ie. add another drive to an existing RAID 5 array) but in my experience they take forever to do so.

 

[LethalWolfe]

Unless you are working w/hi-end video the only thing a RAID does is add one more thing to break or malfunction.

It sounds like you should follow pdpfilms advice as I think you want a back-up, not redundancy.


Lethal