Raid and Storage gurus I need some input please

[GCS]

First the server

Supermicro Server Motherboard
4gb of DDR2 ram
Intel Quad Core CPU
Norco 4020 case
800W Corsair Power Supply
Areca ARC-1270 24 port Raid Card with added memory AND battery backup
(6) WD 1TB Green Drives - in one Raid 10 Array
(4) WD 2TB Green Drives - in a second Raid 10 Array
Windows Vista Ultimate 64 bit


Used for DVD rips, photos, and music.

I use Sage HD200 boxes to access this stuff.

Server is used for nothing else.



Concerns:

Been reading up lately as I was about to buy some more 2TB drives and it seems that the WD 2TB drives are not rated for RAID nor are the 1TBs I am using. And if they fail while being used in RAID I cannot get them replaced under warranty :Q

Needless to say I am a little paniced and worried now that I may be in jeopardy of losing all my data AND not be able to get new drives. Some of which is not retrievable the rest is not easy to retrieve.


If this is really the case what drives should I be using?


Also, so that I do not have to panic in the future how would back up this much data in the case of failures? Each Raid array is about 1/2 full at this time.

Thanks in advance for your advice.

Greg

 

[tomt4535]

Using RAID 1 you can have a drive failure, and your PC will continue to work like normal and will not lose any data. If you are using RAID 10 (a stripe of mirrors), all but one drive from each RAID 1 set can fail without damaging the data. Wikipedia explains it a little better than I do : http://en.wikipedia.org/wiki/N...ID_10_.28RAID_1.2B0.29

As far as getting a new drive under warranty, I have never heard that they wouldn't replace a drive for just being in a RAID array. Even so, they don't need to know it was in a RAID setup. I have replaced drives from WD before without even having to talk to a person so it shouldn't be an issue.

 

[GCS]

Well I am running my (2) arrays with tolerance for 2 failures on each drive so that must be Raid 6?? I must have my Raid #s wrong as I thought it was 10

Basically the drives on each array are spanned to make one large drive with 2 of the drives in the chain for up to 2 failures per array. Basically I have 4TBs of space on each array to use.

 

[pjkenned]

If you have 2x 4TB available you are using Raid 6. if two drives in either array fail, you will be able to access data on the array still.

This is very close to what I do in my Norco 4U set up as a WHS, except I'm using the Seagate 1.5TB drives with an adaptec controller, and have Raid 6 arrays. Raid 10 would be giving you 3TB on the 6x 1TB array I think.

 

[Cr0nJ0b]

let's first start with the right terms.

Spanning = Joining multiple drives together into a larger volume. This creates a large volume where data is written to the first drive...until it's full, then to the second drive...etc. In a spanned array you can lose a drive and I believe you can still recover some of the data. I've never done this, but I've heard it's possible...

RAID 0: also called striping. Here the the volume is created by joining multiple drives into a single large volume like spanning. Bun unlike spanning, data is written across all the drives in block format and in a stripe. So, when you write a file it will land in pieces across all of the drives. This is great for speed, but if you lose a drive, you lose small pieces of all the files and thus you lose all the data.

RAID 1: Mirroring. This is a simple form of redundancy. Data is written at nearly the same time to two separate but equally sized volumes. You read data only off of the primary volume (in most cases) and would only access the mirror volume when the primary is down. This give great reliability for fault, but at the cost of 100% of the storage capacity.

RAID 10: Is a combination of RAID 1 and RAID 0. Generally you setup a RAID 0 volume of 2 or more drives and then you create another equal volume with another set drives. The RAID 0 stripe is fast, so you get more IO, but as mentioned earlier it can fail...so that's why you have a mirror.

I've never heard of mirroring spanned volumes. Generally The only reason I would span volumes is to put together multiple drives with different capacities. It's not optimal for performance.

If I were you I'd stick with what you have and not worry about the warranty. here is a link and I can't find anything that says it's void for RAID use. That would be idiotic of them IMO. I also can't understand someone saying that drives aren't "rated" for raid. What they might be saying is that they aren't all that fast, and probably wouldn't be a good choice for RAID. That is a question for the testers...As you have seen, it does work.

As for backup...this is what I do. It's not all that great, but I'm ok with it.

I have 3TB usable on one server (RAID 5)
on another system I loaded a RAID0 stripe of 3 1TB drives. I use rsync to copy the data from one server to the other...then I shut off the backup server. I do this about once a month. Most of my data is static, so my window for data loss isn't all that great.

If you need more frequent backups then leave the system turned on, add more disk (50% more than your available) and do incremental backups using some backup software. with compression that might give you a longer windows for recovery versions.

 

[Madwand1]

WD has a utility which you can use to turn change TLER options.

http://en.wikipedia.org/wiki/T...Limited_Error_Recovery

 

[Emulex]

you want raid 1+0, if you had 6 drives you'd have 3 raid-1 sets of 2 disks that would be striped.

1+1 1+1 1+1
0-------------0

so any "1" could fail, up to 3 as long as they were in the same pair.

a good raid controller will read from all 6 drives at the same time to boost read iops