Setting up RAID 0+1

[Xynok]

I'm using an ABit KR7A-133R, and I'm going to setup RAID 0+1. My question is, what do I set each HDD to be? Master, CS, Slave? I assume I should set each as Master (Both drives on the stripe array + the mirror array of the stripe). Anyone know? Anything else I should be aware of?

Thanks in advance. I'm using 4xIBM 80 GB ATA100 drives. I am using one drive as the primary master on IDE 1 for the OS and applications, and the other 3 drives to setup the RAID as per above, to be used for data.

 

[Lars_Coleman]

Well, with RAID 0+1 you need four hard drives. So you will need to set one as a Primary Master, Primary Slave, Secondary Master, and Secondary Slave (I would stay away from cable select). Other then that once you have the connections you define the array from the BIOS for the RAID controller.

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Xynok]

From everything I have read, I will only need 3 HDDs. 2 for the stripe array, and 1 to mirror the stripe.

 

[Lars_Coleman]

<A HREF="http://www.storagereview.com/welcome.pl/http://www.storagereview.com/guide2000/ref/hdd/perf/raid/levels/multLevel01.html" target="_new">RAID 0+1</A>

You need four.

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Xynok]

You are correct. Thanks.

 

[Xynok]

One more question.

If I use 4x80GB drives with 0+1, I will have 80GB of storage, correct?

Thanks again.

 

[Lars_Coleman]

You will have 160GB. You are going to stripe 2x80GB which equals 160GB and use the other two to mirror the information on those two drives.

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Xynok]

Right, but that link you provided, in addition to what I have read, indicates the storage efficiency will be 50%. So for 160GB, that would be 80GB? What am I missing?

Sorry, this is the first time I have done this (obviously), and I'm just trying to get everything straight before I start buying the drives.

 

[Lars_Coleman]

Array Capacity: (Size of Smallest Drive) * (Number of Drives ) / 2.

In your case:::
80GB * 4 = 320GB / 2 = 160GB

The storage efficiency would be how it uses the storage. You are only using 50% of the storage space available.

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Xynok]

GAH! Thanks for you patience. Is it Monday yet?

 

[Lars_Coleman]

I hear ya there. I hate waking up on Monday!!

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[Xynok]

One more question and I'll leave you alone.

What drives do you suggest using? I wanted to use Maxtor ATA133s, but have found that people think ATA100 vs 133 is negligible at best performance wise, and that Maxtor isn't the best. Also, I was going to use IBM drives, but have been reading about issues with them. I also read about the Seagate timing issues in RAID, so I'm avoiding them too. So I guess that leaves Western Digital. Should I use WD drives or are the ATA133 Maxtors solid?

Thanks for everything.

 

[Lars_Coleman]

I like the Maxtor drives and that is all I buy. The new D740X series is a really good drive so far.

The ATA133 interface wasn't made for speed, but to overcome the 28bit LBA limitation that the other controllers have. ATA133 is as fast as the drive, and the drive isn't even sustaining the bandwidth of ATA66 at this point.

All I buy is Maxtor drives. Here at work I have a 60GXP in my IBM Netvista. But from there I didn't like my old Western Digital, but the new one's sound really nice!

<font color=red>People and hard drives are like bandwagon fans and sports!</font color=red>

 

[ath0mps0]

Unless you can afford the 120GB WD "JB" series with 8MB cache, the Maxtors are the best IDE drives for your configuration. Out of curiosity, what will you be using the RAID 1 mirror for? The RAID 0 is of course for performance - but if you are "only" buying 4 drives, you're probably better off using the other 2 for backups in removeable drive trays - unless this is a critical server that you can't have offline for more than a few hours during a business day should one of your RAID 0 drives fail. RAID 1 does not replace backups - it only helps keep the server operational if a drive fails. There are countless other ways to lose data that can only be mitigated by backing up and taking the backup off-site.

I thought a thought, but the thought I thought wasn't the thought I thought I had thought.

 

[Xynok]

Good question. Yes, this machine must be up 24/7, as it serves many people from many different timezones. If I lose a drive, I need to be able to replace it asap.

As for backup, I will be using an Onstream 60GB Tape drive to backup the stripe array. The mirror is in case I lose one of the stripe drives. The OS/App HDD isn't much of a concern, as it can be rebuilt from nothing in under an hour if I had to.

 

[ath0mps0]

Have you considered RAID 5? The controllers tend to be more expensive, but you only lose one drive (80 * n - 80), not half your total storage (80 * n / 2) and you will have lower CPU utilization. With 3 drives you would have the same available storage (160GB) as 0+1 and with 4 drives you would have more storage (240GB) and higher performance.

I thought a thought, but the thought I thought wasn't the thought I thought I had thought.

 

[Xynok]

Well I am not afraid to admit that RAID is new ground for me, and I will comment on your question. I am using the Highpoint RAID controller that comes on the board (ABit KR7A), and it only supports RAID 0+1 max. So, what does a controller that supports RAID 5 cost? Also, how easy is it to configure/install? The BIOS setup, etc. with the controller on the board looks really easy, and I've researched how to do it quite a bit. Also, I need a controller that is compatible with Linux.

My goal here is to setup a solid File server for under $3000.

 

[FatBurger]

Pretty easy to configure, but you're looking at $400 or more for the controller, last I checked.

<font color=blue>If you don't buy Windows, then the terrorists have already won!</font color=blue> - Microsoft

 

[kief]

Yeah, unless yer shelling out alot of cash stick with what you have. If you do decide to upgrade the controller will be better (faster, less CPU usage) then what you have which is a chip that then uses software to do the work. Even still though id spend cash on the 8meg Western Digital drives before id buy the expensive RAID card, or get both if the budget was that big =)

Jesus saves, but Mario scores!!!

 

[ath0mps0]

Promise SX6000 is available on newegg.com for $245 new, $183 refurb. This card has 3 channels - will support up to 6 drives in RAID 0,1,0+1,3,5 (5 being the best, IMHO). This will cost about the same as one WD "JB" 120GB drive. RAID 5 uses striping similar to RAID 0, but with parity on each stripe. So, if you lose one drive the array will continue to function. It is much more efficient than RAID 1 in that you only lose the storage capacity of 1 drive, no matter how many you have - i.e. with 5 x 80GB you have 320GB available capacity and with 3 x 80GB you have 160GB capacity, etc.

I thought a thought, but the thought I thought wasn't the thought I thought I had thought.

 

[FatBurger]

I didn't realize they were so cheap now. I may look into that down the road then.

I always forget how <A HREF="http://www.promise.com/product/subsys_detail_eng.asp?pid=86&fid=2#" target="_new">huge</A> they are, though.

<font color=blue>If you don't buy Windows, then the terrorists have already won!</font color=blue> - Microsoft<P ID="edit"><FONT SIZE=-1><EM>Edited by FatBurger on 04/16/02 12:21 PM.</EM></FONT></P>