New Mac Pro Raid Card for Raid 0 required?

[ncc1701d]

Hi. Just wondering if I will need the Raid Card for Raid 0 in the 2009 Mac Pro or can it be done with software (Is it even worth doing in software?)

My plan is to use Raid 0 to increase the speed for video editing over 4 x 1 TB hard drives and use Drobo to back up using Time Machine. Any problems with doing that?

Thanks!

 

[BlueRevolution]

If you're looking for significant speed increases, definitely go hardware RAID. Software will work, but it won't give you the results you're after.

 

[ncc1701d]

If you're looking for significant speed increases, definitely go hardware RAID. Software will work, but it won't give you the results you're after.

thanks, looks like I'll go with the raid card then. Do you see any potential problems with the set I want to go with?

 

[BlueRevolution]

Not aside from the inherent problems with RAID 0. If you're aware and willing to accept the risk of data loss, which it sounds like you are, then you should be fine.

 

[ncc1701d]

Not aside from the inherent problems with RAID 0. If you're aware and willing to accept the risk of data loss, which it sounds like you are, then you should be fine.

yeah, I was reading on wiki that raid 0 is good for speed increases but no protection. That's why I was thinking the drobo would be the way to go for back ups. That way, if any of the main drives fail I'll be able to replace them and load everything back from drobo. Please let me know if you think I'm on the wrong track.

My other problem is that I want larger drves, 2TB if I can. Is it possible / wise to have a 640GB drive for the OS and then buy 3 x 2TB drives in raid 0 fir storage of everything? (as well as backing all that up to drobo?)

 

[BlueRevolution]

I would not run 2 TB drives in a RAID 0. In fact, I wouldn't run them at all at this point. They're bleeding edge, and this early on in the product cycle it is likely that there will be a high failure rate. Since a single failure destroys a RAID 0 array, don't even think about building one with anything less than rock-solid drives.

If you have 4 drives, you might want to consider using RAID 10 (0+1). The upside is that it will be even faster than RAID 0 and offers more data protection than a single physical disk. The downside is that you lose half of your storage space, so you'd only get a 2 TB array from 4x1 TB drives.

Dedicating a single drive to the OS isn't a bad idea, though.

 

[ncc1701d]

I would not run 2 TB drives in a RAID 0. In fact, I wouldn't run them at all at this point. They're bleeding edge, and this early on in the product cycle it is likely that there will be a high failure rate. Since a single failure destroys a RAID 0 array, don't even think about building one with anything less than rock-solid drives.

If you have 4 drives, you might want to consider using RAID 10 (0+1). The upside is that it will be even faster than RAID 0 and offers more data protection than a single physical disk. The downside is that you lose half of your storage space, so you'd only get a 2 TB array from 4x1 TB drives.

Dedicating a single drive to the OS isn't a bad idea, though.

Thanks Blue Rev! I'm afraid it's back to the raid wiki for me! I only went as far as Raid 5 and stopped I'm after the storage, so dont' know if loosing half on the main computer is what I'm after. Looks good though. I'm sensing you're not too keen on the drobo?

I think you're right about the 2TB drives actually and probably why Apple didn't go with them in the Pros. I'll stick with the 1TB's. Cheers!

 

[BlueRevolution]

Well, everything after RAID 5 is just a bunch of ditto marks anyway. RAID 10 is just a RAID 0 array of RAID 1 arrays, so two pairs of disks mirroring each other: [(A A)(B B)] where the brackets are [0] and (1).

I sort of ignored the Drobo. It's not that it's a bad idea, but I just prefer to avoid seeing an entire RAID array collapse due to one drive failure. However, that's not to say that the Drobo would be useless. You could certainly set up two RAID arrays, even different types, according to your needs. I'm not a video editor, so can you give me an idea of what the size and performance usage will look like?

If you want a maximum-performance scratch drive, get two high-performance hard drives and run them in RAID 1. The storage capacity won't be much, of course, but if it's a dedicated scratch disk that may not be an issue.

 

[Horst]

I completely disagree with Blue, I'm afraid .

Afaik, Software Raid0 in OSX is equally fast as Hardware Raid0; also, Raid1 will not increase speed by any significant margin, that's what Raid0 is for.

 

[BlueRevolution]

Fair enough. I have some mistrust of software RAID solutions from past experience, but that could be misplaced.

I haven't performed any benchmarks, but by my understanding, RAID 0 and RAID 1 are comparable in terms of write performance, but RAID 1 has a significant edge in reads because the two drives can act completely independently. However, no matter how fast RAID 0 is, I still wouldn't recommend using it. The cost of array failure is too high. Even if you do have a full up-to-date backup, the array needs to be rebuilt and restored, and you can't come back online until the failed disk has been replaced. With a RAID 1, given the appropriate hardware, it's possible to replace a failed disk without even turning the system off, let alone dealing with restoring backups. The Mac Pro can't hot swap, of course, but the process is still trivially easy.

It's a safety blanket.

Bottom line: make up your own mind.

 

[Horst]

I haven't performed any benchmarks, but by my understanding, RAID 0 and RAID 1 are comparable in terms of write performance, but RAID 1 has a significant edge in reads because the two drives can act completely independently.

Not quite right, a single HDD is equal in write performance to Raid1, but a tad slower in read .

A 2-HDD (internal/straight eSATA) software Raid0 (Tiger/Leopard) is almost twice as fast as both a single drive and any Raid1 array, re. read/write .

You are completely right about the risks of Raid0, but for a truely fast scratch or data volume there is no substitute, until SSD is ready for prime time.
Imho.