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RAID-5 Setup - Requirements/Questions?

I

im333mfg

n00b
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Dec 10, 2004
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After looking through the various threads for answers, I've finally decided to post my question.

I'm looking at setting up a 10-12 disk RAID 5 Array (in upwards of 2.5 - 3TB) over the next few weeks. This will serve as a file server for my media, files, dvd backups, and pvr server. There are a couple of questions I have on the hardware and setup side of things, that hopefully everyone can chime in on..

First, here are the items I am looking at purchasing (if anyone has any suggestions different then what I've listed, please let me know):

1 x 3ware 9500S-12
2 x 3x5.25 to 5xSATA Enclosure
10 x 250GB Hitachi SATA HD

Now for the questions. I am going to be needing to buy a power supply to power this setup, and am wondering, are there any out there that can suffeciently power 10-12 drives, or would I need to do a dual power supply setup?

Also, I've noticed that a bunch of people on the forums have large RAID arrays which they use at home, and was wondering, one, it is advantagous to, once the arrays are setup, to then partition them according, or just leave it as one huge partition? Also, the 3Ware card supports a varity of RAID setups, would RAID 5 be the best for this type of setup? Would RAID 50 be any better for something like this? Any one have any opinions on use a port or two for drives in case of failure within the array?

I'm also looking for a backup solution (as RAID is great for mass storage, but shouldn't be used without backup). Any suggestions on this side of the field? I would not need to backup the entire amount of storage, but there will be a sizable chuck that will need backing up..

Any opinions, suggestions, and comments are greatly appreciated.. I am fairly new to the RAID arena, and would just like some input.. Thanks.. :)
 
pcpowerandcooling.com

You probably want to look at getting a pair of 400gb disks to back up onto. Disk-to-disk backup is currently cheaper than tape or DVD or anything else.
 
For power, you don't need to much, figure about 25 watts per HD is plenty. I have Compaq external SCSI arrays and they only use a 200 watt power supply which spins 7x 10k disks with ease. I'm currently using 14x 36 GB disks for my RAID 5 array and it's all in one partition for simplicity. RAID 50 is not really needed over RAID 5 in most cases as long as you make sure you have a hot spare drive online at all times, and keep another spare identical disk on hand just in case of a failure.
 
I though the whole point of having RAID5 was so that you wouldn't have to worry about backing up. The parity drive will enable you to operate even if one of your drives fail (albeit a lot slower).

I have a friend who uses a PCP&P 510 for his power needs. It powers 12HDs, 3 optical drives and a prescott without any problems.
 
MYST1K said:
I though the whole point of having RAID5 was so that you wouldn't have to worry about backing up. The parity drive will enable you to operate even if one of your drives fail (albeit a lot slower).

I have a friend who uses a PCP&P 510 for his power needs. It powers 12HDs, 3 optical drives and a prescott without any problems.
Click to expand...

A RAID 5 Array, from what I understand, can withstand 1 drive failure within the array.. Thus if say 1 drive were to fail, then during rebuild, a 2nd were to fail, I'd be SOL.. Thus the reason I'm looking for some sort of back.. I could do DVD's, but thats a lot of DVDs to pop in and out in order to back things up..
 
RAID 5 is setup so that if one disk fails, your array goes into a degraded mode until you replace the faulty drive and rebuild the array. You can, with that 3ware card, setup the array to have a "hot spare", which will be around just incase one drive fails, it will start to rebuild the array immedately, in which case the vulnerable time in which you can lose the entire array if another drive fails goes from replacement time + rebuild time to just rebuild time. I would highly recomend having 10 data, 1 parity, 1 hot spare if you have a 12 port controller.

Also remember that windows has a 2TB limit on partition sizes (one of the other threads in here where people had 12 250GB drives and couldnt get the full 2.5TB size).

RAID-5 does not absolve you from making backups

If you get a virus or just simple user error where the data gets deleted and/or overwritten, the backups can save you a lot of time... RAID-5 only protects you from hardware failure.

Now if you're ripping DVDs and CDs, the physical media is infact the backup in terms of content. But time wise, you have to asses whether ripping 100 DVDs is time consuming enough to warrant some sort of tape drive mechanism to backup your data.
 
more importantly would be that the drives require 2A per on the +12V rail to spinnup
review > How to Buy a PSU
and check to see if the card supports a delayed spinup option (which is likely)

in addition to the 2TB partition limit
consider you also have the 4 primary or 3 primary and one extended partition limit
when working up your partitioning strategy

Id say Dual Layer DVD for a set of full backup with additional DVD or CD incremental
and plan on Full Backups every couple of months?
depends on use

a partial list of the things that can go wrong with a RAID5 array (or any RAID)
1. user error
(massively underated as the cause of data loss, I migrated my array and following the instructions did worry about the cables to drives, that happened to be an issue with the BIOS I had,
2 channel array AB or BC
3 channel ABC ACB BCA BAC CAB CBA
6 channels 720 possible combinations of drives to channels :rolleyes:

2. data corruption, have a bad stick of RAM (or any other problem) corrupts the filesystem?
it does it to the whole array

3. infection

4. power event, takes more than one drive at a time, same for any other nasty event from a hurricane to your dog knocking over the array

PC Power and Cooling is coming out wih an EPS12V 850 watt for workstations with serious DAS or NAS\SAN boxes
http://www.pcpowercooling.com/about/whatnew_850_ETX.htm

generally speaking the 510s are good for 12 drives
ive had 10 hooked up to the rig in my sig

but its really dependant on running the numbers for your config and looking at when you incur the darw in a normal powerup cycle
once running drives will generally drop to 1\4 their spinup draw, unlike most components they are likely well documented for power consumption everything from the spinup to the seek draw, so look up the figures at the manufacturers and plug those in to the calculator to run some senerios
 
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