How essential is backup when using RAID0?

[gangst]

Hi,

Basically, I am thinking about moving from my current set up of two 500GB hard drives in my PowerMac to RAID0 for better performance.

However, I have had recommendations to use a backup hard drive to mirror my PowerMac, and so a few questions:

• How essential is a backup/mirror when using RAID?
• Do I need additional hardware to make a RAID configuration? (I have seen mention to RAID cards)
• Are there other hard drive configurations which offer greater performance?

Thanks for any advice.

 

[blodwyn]

Hi,

Basically, I am thinking about moving from my current set up of two 500GB hard drives in my PowerMac to RAID0 for better performance.

However, I have had recommendations to use a backup hard drive to mirror my PowerMac, and so a few questions:

• How essential is a backup/mirror when using RAID?
• Do I need additional hardware to make a RAID configuration? (I have seen mention to RAID cards)
• Are there other hard drive configurations which offer greater performance?

Thanks for any advice.

Do you care about the data on your RAID0 disks? If so then you need to back it up. In a RAID0 configuration, a failure in either disk will destroy all your data. Disks fail, and so your data will inevitably get lost if you don't back it up.

You can create a RAID array using disk utility. Alternatively you can buy hardware RAID controllers that handle the RAID'ing within their own firmware. Depending on the card, you could see a performance improvement over using your Mac to do it in software.

 

[Aea]

RAID0 is by implementation very unreliable. The goal is speed and not redundancy. If you value your data you will need to have backups.

I believe you can have RAID5 through software but you'd need to buy two more disks, one for meeting the minimum of 3 disks for a RAID5 config, and one more for your system to boot from.

If money is no barrier then RAID10 is the best, but it's expensive (four drive minimum) and I don't know if your machine will support it.

 

[blodwyn]

I believe you can have RAID5 through software but you'd need to buy two more disks, one for meeting the minimum of 3 disks for a RAID5 config, and one more for your system to boot from.

RAID5 is not available using disk utility, nor by using SoftRAID. So AFAIK there is no option to get RAID5 using software. You can however download the latest ZFS binaries, and create a ZFS RAIDZ array using 3 disks. I've had a RAIDZ running for a few months with zero issues (using USB external disks on a hub - chosen deliberately as a torture test being the worst configuration I could come up with).

 

[atszyman]

One thing that you might also be mindful of is to have a second compatible RAID controller handy. We had a computer at work fail and with the disks set up in a RAID5 array, I could not find a compatible controller that would boot and recognize the drives. We eventually got the computer up long enough to get the data but it did point out that while RAID5 protects you from a disk failure, a RAID controller failure could be just as bad.

I have a RAID1 array running at home although I've had issues with them at work, but at least in a RAID1 configuration every disk is still independently bootable since both disks should be perfect copies (up until some sort of RAID failure.

 

[Trip.Tucker]

RAID5 is not available using disk utility, nor by using SoftRAID. So AFAIK there is no option to get RAID5 using software. You can however download the latest ZFS binaries, and create a ZFS RAIDZ array using 3 disks. I've had a RAIDZ running for a few months with zero issues (using USB external disks on a hub - chosen deliberately as a torture test being the worst configuration I could come up with).

I'd also recommend looking into ZFS setup in a RAID configuration, you will have more options than using existing, established RAID configurations.

 

[akm3]

"How essential is backup when using RAID0?"

Exactly as essential it is when not running RAID0. And I'm not being snarky.

 

[sickmacdoc]

"How essential is backup when using RAID0?"

Exactly as essential it is when not running RAID0. And I'm not being snarky.

Not snarky at all! Perfect description!

 

[atszyman]

"How essential is backup when using RAID0?"

Exactly as essential it is when not running RAID0. And I'm not being snarky.

Actually I'd say when running RAID0 backing up is even more essential. By striping across two different HDs and having a single HD failure lose all the data, you effectively double your chances of a catastrophic data loss, and that's without factoring in the possibility of losing the RAID controller with no compatible backup.

 

[akm3]

Actually I'd say when running RAID0 backing up is even more essential. By striping across two different HDs and having a single HD failure lose all the data, you effectively double your chances of a catastrophic data loss, and that's without factoring in the possibility of losing the RAID controller with no compatible backup.

I disagree, either you need that data backed up or you don't. Saying it is MORE essential to backup because the likelihood of failure has increased misses the point that it is absolutely essential ANYTIME you have data that is important being stored on something with a non-zero chance of failure.

If there is a non-zero chance of failure, and the data is important, it is essential to backup. Whether it is on RAID0 and twice as likely to fail or not.

"There are two types of people: Those who backup, and those who will"

 

[sickmacdoc]

I have to agree because in the definition of the word essential it does not note degrees of "essentiality" if you will- either something is essential or it is not. I happen to feel that backing up data is simply essential under all circumstances- be it a single single drive or a multi-drive RAID setup. Obviously some people do not feel that backup is essential or we would not see the number of requests that we do for help in recovering lost, deleted, corrupted or generally mangled data. Drives screw up, users screw up and programs screw up, so I will always preach complete backup!

Now if we want to discuss the likelihood of a drive failing and putting a person in the position of needing to use the backed up data to recover, that is another matter and we can use degrees of likelihood. It is, by RAID 0's very nature, more likely to need to use a backup for a drive failure in an RAID 0 array if only because of increased potential failure points, any one of which will kill the whole.