Mac Pro + RAID storage

[The Dude]

I'm a bit wet behind the ears when it comes to external RAID arrays and am speccing a new Mac Pro with the idea of getting one of these;

http://www.store2go.net/shop/ultimatestorage/p/pro...

instead of specifying internal drives in the Mac.

Can anyone tell me what connectivity is needed to run the RAID - I see it has ethernet and USB ports but do I need a RAID controller in the Mac? And generally, is the RAID in the URL a decent one? The price seems too good to be true - specifying a similar amount of storage from Apple costs an extra £1900!!!

Thanks

[sp60]

Dunno what your level of knowledge is, so I'll presume very little!
Raid is simply a way of getting more than one disk to be useable as one big disk, providing added speed and/or reliability depending on how you set it up.
You won't be able to entirely replace your new machines internal hard drive setup with an external setup as the machine needs to boot from an internal drive. You may be able to get it to boot from the external drive, but the performance of an external raid compared to even a single none raid internal drive will be terrible and it will be very complicated to set up, so you shouldn't consider this unless it's an absolute neccessity.

What is it that your hoping to achieve from using a raid array? speed, capacity, or resiliance? (or all of them!)

[ehasler]

I've got a similar RAID box (Infrant Readynas+ in my case) plugged into my Mac Pro, and you don't need any software on the Mac - it just sees it as a network device, so you mount it as an additional drive in Finder.

The best way to connect is via a Gigabit switch (I paid about £30 for mine at PC World), although it is possible to connect Mac -> RAID box directly with a network cable.

It doesn't replace the disks in the Mac (it's quite slow - 15-20 MB/s vs 60+ for an internal drive), but is simply additional storage. The onboard drives can be configured as RAID 0 (striped - more performance, less resiliance) and RAID 1 (mirrored - same performance, more resiliance).

I have 2 x internal drives mirrored as my system drive, and 2 more configured as RAID 1 for Photoshop scratch space and data files, which I also backup to the RAID drive.

[The Dude]

Thanks for the reply.

All I really know is the theory of RAID arrays so I know what they are and (sort of) how they work, but never had to set one up or use one other than invisibly on the office network. This one is for home though.

The main reason for choosing the RAID was just because I was doing a price comparison between specifying internal drives on the Mac (oh yeah, I know that I'd have to specify 1 internal drive as a system/boot disc) versus the same amount of storage on an external array (3tb).

It will be used to render large amounts of animated graphics (Maya->Quicktime most likely) so I don't know if out-and-out speed is that much of an issue - data integrity would be and the portability (are they?) is kind of attractive (for reasons I won't go into here).

[ehasler]

The Readynas is quite small and easily portable. These external drives do come in different versions though - there are Network Attached Storage (NAS) drives, and Direct Attached Storage (DAS) drives.

The NAS boxes are more useful if you want more than one machine to share the data - in my case I've got a laptop and a Squeezebox music jukebox thing that connect to my Readynas, and can access the same data as my Mac.

You can get DAS RAID boxes too - I have a Thecus box which takes two drives and can run in RAID 0 (fast) or RAID 1 (secure) mode, and connects via USB (some also connect via Firewire 800, which is probably the fastest way to connect on a Mac Pro).

Also, remember that Apple charge a fortune for their drives, so spec it with just 1 drive, and then buy additional ones from elsewhere.

[sp60]

Ok, I see, don't forget that the storage specified in that advert is if you use all of the available slots for raid0 or JBOD, either way it offers no resilience at all and (arguably) a higher risk of data loss. The add states that the device comes with 4 x 750GB drives. If you wanted resilience you would need to have at least a mixture of raid 0 and raid 1, cutting your capacity in half.
It should be cheaper to simply add drives into the mac pro, as long as you buy the version that is Raid capable. As is said above, buy the mac pro with only one drive, then buy your own drives (from a different reseller) to add in. I bought a couple of SATA 300 750GB drives this week at £112 each, but they can be had for under a hundred quid each. It should be relatively simple to set up and will save a fair bit of cash over buying the seperate device. This doesn't give you the seperation that you say may be a benefit though.

[ehasler]

sp60 said:

The add states that the device comes with 4 x 750GB drives. If you wanted resilience you would need to have at least a mixture of raid 0 and raid 1, cutting your capacity in half.

RAID 5 gives resilience, and with 4 x 750GB drives fitted, you'll have just over 2TB of storage available (i.e., you lose the capacity of 1 drive)

[The Dude]

Great replies guys, thanks.

[The Dude]

sp60 said:

then buy your own drives (from a different reseller) to add in. I bought a couple of SATA 300 750GB drives this week at £112 each, but they can be had for under a hundred quid each. It should be relatively simple to set up and will save a fair bit of cash over buying the seperate device. This doesn't give you the seperation that you say may be a benefit though.

Presumably any brand of SATA 300 drives will be compatible? Any particular brands to go for, or for that matter avoid like the plague?

[sp60]

ehasler said:

sp60 said:

The add states that the device comes with 4 x 750GB drives. If you wanted resilience you would need to have at least a mixture of raid 0 and raid 1, cutting your capacity in half.

RAID 5 gives resilience, and with 4 x 750GB drives fitted, you'll have just over 2TB of storage available (i.e., you lose the capacity of 1 drive)

Yes, sorry forgot to add that in, although i'm not a great fan of raid 5 without a hot spare as we had 2 drives go in an array once and it skewered the lot. That made me learn about raid! Have to add that the raid 0+1( or 1+0 ) can survive two drive dropouts, but only if it's the correct two! Both setups work in drive pairs, but in slightly different way. Similar capacity would be gained using raid 5 (3 disk array) with a hot spare, but in this case any two disk failure could be recovered as long as the array had long enough to rebuild itself in the interim (and your raid controller supported on the fly rebuilding which built in ones may not). But I think that the suggested raid5 option is best in your situation, good capacity, speed and resilience, AFAIK that's what most server use (ours certainly do).
Could detail on Raid:
http://en.wikipedia.org/wiki/RAID

As far as what drives to use, you are better to have matched drives, some controllers require it, but on others it's not crucial as long as the capacity is the same. Personally I would avoid maxtor drives, we've had 8 failures (from a pool of around 22) in 2 years, of their 160GB drives, but there was a known bad batch of them, so recent ones could be ok. Seagate drives currently offer good price for large capacity and come with a 5 year warranty, I never had a problem with a seagate drive. Western Digital also doing good high capacity drives, with a good reputation.