[benz]

hi, i am new to RAID and know very little about this. I am planning to build an archive server with RAID in the radiology department to store the imaging files.
i am thinking using a mac pro with 3T storage and RAID card, using RAID 0+1 from four 750G HDs.
as i am dealing with about 1.5T data every 2yrs., so with RAID 0+1 in 4 HDs, then i can have 2 copies of ~1.5T in my mac pro and swap the HDs every 2yrs. i 'll also have a hard copies back up of those data too.
is it a workable configuration? as i am new in RAID, is it easy to config the RAID options with RAID card and RAID software utility in mac?
thanks a lot
P.S. what 's difference between RAID 5 & RAID 0+1
benz

[OreoCookie]

Have a look at this thread. I don't think a RAID 0+1 is the right way to go in your situation. I recommend you have a look at Wiebetech's storage solutions (e. g. the RT5e). Depending on your budget, you might also want to have a look at Apple's XRaids.

If you want to know more about RAID levels, have a look at the page here. The advantage of a RAID5 in short is that you waste less capacity (you can use only half of the total capacity on a RAID0+1 as opposed to 3/4 on a RAID5 with four drives).

[besson3c]

How does Apple's RAID solution fare with RAID solutions from other vendors pricing/quality wise? Hardware RAID solutions are platform agnostic, aren't they?

[besson3c]

I would not go with consumer grade hard disks if this data is important to you, and I'm a big fan of RAID 5 solutions for when you need this type of data capacity. I would go with a hardware RAID 5 solution.

[OreoCookie]

The XRaid has a good price/performance for a professional storage solution if you compare it to similar offerings by Dell, Sun, IBM and HP, for instance. AFAIK it's even certified for Windows, so yes, it's platform agnostic. You need a FiberChannel card, though.

[besson3c]

The SAN we are using here at work requires drivers for the Solaris machines hosting these disks. Are there typically vendor specific RAID drivers, or just generic OS support for recognizing RAID arrays?

[OreoCookie]

According to Apple, `Xserve RAID works well with Mac OS X Server, and you can use it with Windows-, Linux-, Solaris- or NetWare-based servers as well.'
I haven't used an XRaid for a long time (first-gen PATA version only for a brief time), so I don't know whether you need special drivers, but I would assume so. I also assume that you will get the best user experience under OS X.

[mduell]

You can either buy the XRaid, an external enclosure that houses the 14 disks and a RAID controller, or you can buy a hardware RAID card for the Mac Pro. For your needs I'd suggest 3x1TB drives in a RAID5 array using the RAID card in the Mac Pro; the XRaid is overkill for your amount of data.

[benz]

thanks for all above comments.
as i am not a IT specialist, so for vendors other than Mac, i ve no experience at all and also not sure if available here in my city.
i ve been mac user for several yrs., now using mac book pro with osirix for image viewing and also use it as a very small scale pilot archive server in my department ( storage just ~120G). but seems work very well. that's lead me to think bigger and use a macpro 3T, quadcore, dual DVD burners, RAID card as a archive server as mentioned.
i also heard of Mac X san, Xserve, but that's too difficult for me technically.
moreover, those X san, X serve are more expensive and may just be an overkill in my scenario.
actually the data traffic is not heavy, and we are just using 100M/sec cable in out network.
-----our preliminary plan is to use 2 mac pro with config. above, RAID 1, or RAID 1+0, or RAID 5? , plus DVD backup copies, so 4 electronic copies, and 1hard copy backup,
--our concern is fault tolerance, so will RAID 1 be a better option?

thanks again

benz

[besson3c]

RAID 5 is your best option for fault tolerance. One of us could give you a quick intro to RAID 5, but it would probably be best to read up on this yourself since this is important to grasp.

With a RAID 5 solution and enough hot spare drives, you will have data redundancy, but you will not have an off-site backup which is another important consideration. What happens if your site is destroyed due to fire, flood, a hurricane, etc.? If your data is valuable enough, you might want to look into network backups to another site altogether. DVD backups are also an option, but this would account for a ton of DVDs and a lot of burning. A better option might be tape backup, or offsite disk like I've alluded to.

Before you get too engrossed in looking at all of these products and your choices, i would think very carefully about what your needs are here in terms of disaster recovery, and how much money you want to put into this plan.

[benz]

thanks, i 'll explore more in RAID 5, with above setup, the 2 mac pros 'll be in different sites of the network, and of course DVD copies also in another site. i agree that DVD copies is space consuming, but seems improved a lot comparing present situation of CD backup now, each week turn out to be ~60CDs !!!!!!, running for past 3yrs.
is it more diffcult to set RAID 5 comparing RAID 1 ?

benz

[besson3c]

Different sites on the network meaning within the same building? If so, this is not a full disaster recovery plan, just so you know.

Have you looked into tape backup? This might be a better alternative to both CD and DVD.

Most RAID 5 solutions will provide you with an array of disks with amber lights on the front to show you when a disk has failed. When you replace a disk, it "levels", meaning that data is automatically copied to it, including the redundant bits used to level other disks. Day to day operation is pretty much just monitoring for disk failures and replacing disks. RAID solutions are designed so that you can pull disks in and out without powering down the array, so as long as you have some spare disks a monkey could swap disks.

You'll need the appropriate PCI card in your Mac to connect to the RAID enclosure/array, and possibly a driver (I'm not sure on this part).

[benz]

different sites mean different buildings....,
" You'll need the appropriate PCI card in your Mac to connect to the RAID enclosure/array, and possibly a driver (I'm not sure on this part)."...
can i just use the mac pro with T storages and mac RAID card in situ alone without setting up external RAID enclosures/ array, drivers....... ?
thanks
benz

[mduell]

Originally Posted by benz 

can i just use the mac pro with T storages and mac RAID card in situ alone without setting up external RAID enclosures/ array, drivers.......?

Yes, and that's what I suggested.

[flabasha]

If you don't need crazy fast throughput, maybe consider this sucker - it seems to be getting rave reviews (no, I don't work for the company)

drobo.com

It's an interesting thing, especially the aspect that its method of distributing data means that it in some ways is even more redundant than RAID 5. It wouldn't work for me, because it's USB 2.0 only, and I need a RAID that can push HD video realtime. But if you don't need that throughput and just have a ton of data you want available and safe, this looks pretty neat.

[benz]

thanks , but i don't think drobo has distributor here in my city, but mac seems very easily available and i do have experiences in dealing with mac stuffs, and it's quite impressive

[OreoCookie]

I would suggest you get an external RAID, e. g. a WiebeTech RT5e. It's very easy to configure and easily expandable. Plus, you get more space (the WiebeTech tower uses five drives, not four, giving you (5-1) drives in terms of capacity: if you put in 5 1 TB drives, you have 4 TB of capacity. One drive may still fail, so you get the same failure protection as in a RAID0+1 -- which has only half of the capacity.

A RAID5 distributes the data and some checksums equally across N drives. Since you have the checksums as additional data, one of these drives may fail and you can simply continue working (although you should replace the faulty drive immediately). With a WiebeTech RT5e, an XRaid or any other professional RAID solution, you can replace the drives while the RAID is running. It will immediately start to rebuild the data (although that may take a few hours).

A RAID0 spans the data across several drives. If one drive fails, all data is lost. A RAID1 mirrors one drive to another, so one of the drives may fail. If you combine a RAID0 and a RAID1, you get a RAID0+1. The smallest such configuration consists of four drives: e. g. you use a RAID1 to mirror two drives and then combine those two drives with a RAID0. You end up with half of the capacity of all four drives and one drive may fail without interrupting operation.

Another very important point is the following: a RAID (no matter which one) is not a backup solution. You absolutely need a backup solution in addition to this. I second besson's suggestion to have a look at tape drives.

I also think that your Mac Pro doesn't have to have the fastest CPU out there, if all it does is serving pictures to workstations, you should invest in RAM. Also, XServes are not so different from Mac Pros, so I wouldn't exclude them from your considerations. You want to do something complicated for a professional application, you need professional tools for that. XServes run the same MacOS X (Server) that your MacBook Pro can use as well.

So far, I would go for the middle model Mac Pro, put in more RAM (not necessarily from Apple) as CPU power is not as important for a server. (Unless the software does image (pre)processing on the server. Then I'd get a SATA card, a SATA card, a WiebeTech RT5e and drives of sufficient capacity (e. g. 5 750 GB/1 TB drives). In addition to that, you might think about getting a tape drive.

I've given a link to a thread of user experiences on the RT5: it's very easy to set up (the other chap is a photograher/graphics guy, not a geek): pop in the drives and choose the RAID level you want (you want RAID level 5). Then you wait until it's finished.

One more thing: with RAIDs, you cannot just pop in another drive when you run out of storage space, so if you make a RAID5 of 3 drives, then you add a fourth, you won't be able to integrate it into your RAID (well, not without losing your data on the RAID in the process).

[besson3c]

Originally Posted by flabasha 

If you don't need crazy fast throughput, maybe consider this sucker - it seems to be getting rave reviews (no, I don't work for the company)

drobo.com

It's an interesting thing, especially the aspect that its method of distributing data means that it in some ways is even more redundant than RAID 5. It wouldn't work for me, because it's USB 2.0 only, and I need a RAID that can push HD video realtime. But if you don't need that throughput and just have a ton of data you want available and safe, this looks pretty neat.

What happens when one of the disks goes bad with this thing and the data is not recoverable?

[mduell]

Originally Posted by flabasha 

If you don't need crazy fast throughput, maybe consider this sucker - it seems to be getting rave reviews (no, I don't work for the company)

drobo.com

I love the idea of the drobo, but the implementation sucks. Rebuilds/relayouts take forever, the capacity reporting is kind of a hack, and the units have a tendancy to do weird things when copying large sets of data (including, of course, losing it all). Wait for the reviews of v2 if you like Drobo.

Originally Posted by besson3c 

What happens when one of the disks goes bad with this thing and the data is not recoverable?

Pop in a new disk and wait forever for it to rebuild the data from parity.

[OreoCookie]

The drobo is a neat little contraption. It's a very nice plug-and-play device which protects you against harddrive failure. However, it is too slow for some uses (it's a USB 2.0 device after all) and not `pro-grade material'.

I think both disqualify it for the OP. It's a pity, it's a really cool device …