RAID0 and RAID1...?

[rirusstek2]

I just installed two 640GB identical drives setup as RAID.

I set 300GB as RAID0 as to have Windows 7 and a WORK disc.

I set 446GB as RAID1 on the rest of the HDs.

My question would be... In an event that one of the two 640GB drives failed would I be able to retrive the information that would be on the RAID1 HDs, the one that didn't fail?

 

[FredWagner]

I always thought that the RAID configuration was determined by the controller and the drive, and that you couln't have two different RAID configurations on the same pair of drives. You need two separate controllers (or at least controller channels) for RAID 1, right? My RAID experience was mostly with SCSI (lots) and one IDE setup (somebody had set up RAID 0, one drive failed, it was running Netware, and Novell kept trying to rebuild the bad drive. The system was unuseable until the bad drive was disconnected. Then it turned out that the DOS boot files had only been put on one of the drives...the one that failed, of course!)
In my experience, with two drives you're either RAID 0 or RAID 1, not a bit of each.

Fred Wagner

 

[rirusstek2]

Actually, I believed the same but it seems that with Intel Matrix Storage Manager (I'm using a DP55WG Board) you can separate the array (I'm using two drives) to use a portion of volume for one array and the rest to another array.

I set 300GB to RAID0 and the rest to RAID1. It is working very nicely but I wondered in the event that one of the disks fails that I could retrieve the information on the "mirrored" portion of the RAID1 on the other drive.

 

[FredWagner]

Your info will have to come from Intel's support folks. I had no idea that split-personality RAID was possible! You're doing the right thing to find out how it's going to work before you depend on it.

Fred Wagner

 

[rirusstek2]

Believe me, here at Tek-Tips you can find the most reliable advise ever !!!

However, I will ask the folks at Intel as suggested.

 

[rirusstek2]

Well, there is good news and bad news from Intel ...

The good news is that .... YES, when you setup RAID0 and RAID1 in a RAID array (two drives, my case) you can retrieve the information from the part that is setup as RAID1 in the case that one of the drives fail BUT you HAVE to make the FIRST portion RAID1 and the rest RAID0....

This is when the bad news come in ... I set the FIRST portion as RAID0 (thinking numerically) and RAID1 second. Now back to the "drawing board" ... Rest everything.

They told me that it is possible to retrieve the information as I set it up but they don't "validate" that setup.

Anyways .... here is more information

http://www.intel.com/support/chipsets/imsm/sb/CS-022836.htm

 

[FredWagner]

I read the Intel item, and to do what you want, you'll need to back out and start with RAID 1.
FWIW - I've never had a drive failure on my home systems, but they don't run 24/7. On work systems that do run 24/7, I have had occasional failures. One elderly box, with 28 drives, a two drive RAID 1, and two many-drive RAID5's, has had several failures over the years - and last spring nobody noticed the first failure, and it took the hot spare and used it. Then another drive died, we hadn't replaced the hot spare drive, and that volume of the array died and had to be restored from tape after we replaced the bad drive AND gave it a new spare. That server's been in service since 2001, will finally be replaced this year!

Fred Wagner

 

[rirusstek2]

Well, that is for sure a lot of years ... Interesting !!! I did have some drive fail and lost a lot of info and don't want that to happen again, so just in case I'm going to knock the Array down and start over ...

Thanks for all the information and suggestions.

 

[BadBigBen]

Just my opinion:

if you value your data, then get a third drive (or two smaller ones 80 to 200GB each, for RAID 0) for your OS, and set up the two 640GB as RAID I, for Data...

in case that one drive fails on RAID 0, it wont take down your RAID 1 set up. Rebuilding the OS is easier then rebuilding the whole RAID setup you have now...


Ben
"If it works don't fix it! If it doesn't use a sledgehammer..."
How to ask a question, when posting them to a professional forum.
Only ask questions with yes/no answers if you want "yes" or "no"

 

[kmcferrin]

Interesting...I've known about this capability for awhile but never thought to leverage it. You could get a couple of large hard disks, configure the first partition as RAID1 and use it for backups, then configure the second one as RAID0 and store you OS and apps/data on it. Then just run a daily scheduled backup of the RAID0 to the RAID1. You would get the performance benefit of RAID0 with a degree of redundancy via the backups without having to buy extra disks for backup.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCTS:Windows Server 2008 R2, Server Virtualization
MCSE:Security 2003
MCITP:Enterprise Administrator

 

[JimInKS]

Or at least create a fairly small RAID0 just for page and temp files.

 

[Nelviticus]

If a disk died it would be a nightmare recovering the data though - your OS would be gone so you'd need to get a new disk, configure it to be a replacement for the original (i.e. at least matching the matrixed RAID 1 partition) and reinstall Windows.

Bearing in mind that RAID 0 gives you barely any performance boost is it worth it? Any performance gains you do get from RAID 0 will be negated by having your RAID 1 partition on the same physical spindles.

In your current set-up you have 746GB storage and a potential future headache if a disk dies. If you just made a simple RAID 1 array you'd have 640GB storage (only 106GB less) and in the event of a disk failure everything would still work.

I know that's a bit off topic - the answer to your original question is "yes it would be recoverable but recovery would be complicated".

Regards

Nelviticus

 

[kjv1611]

I've been rather curious about the Matrix RAID setups by Intel, myself. I'm glad someone found out about the positioning of the RAID1 and RAID0. From reading their description of it in the marketing points, it sounded like that part didn't matter. But here's something to remember: If you're putting your RAID1 first, and RAID0 second, then I'd say you're not making the best use of your hard drive, and may as well just do RAID1 on the whole thing. The reason is that if you put the RAID0 as the second RAID, you're then using the slowest part of the hard drive for your system partition which is the most important for speed.

So, here are a couple of options I can think of:

Senerio 1:
Disk0:
Partition into 2 or 3 partitions: 1. System, 2. SWAP file/Virtual memory, 3. data/backup
Disk1:
Partition into 1 or 2 partitions: 1. SWAP file/Virtual Memory, 2. Data.

Here's my thoughts there:
Disk 0, Partition 0 = System, Partition 1 = a SWAP file, Parition 3 either left blank, or used as a data backup partition.
Disk 1, Partition 0 = SWAP file, Partition 1 = data file..

Then, you set in your performanc settings custom SWAP/Virtual Ram settings... Disk1,Part0 as your primary SWAP, and then you could also set the one on disk0... That might help a little with performance... or you could use either or, I can see benefits of any of the 3 scenerios for that..

Then if you wanted to use the latter portion of disk0, you could use a backup/sync program to back up your data drive to that portion, so long as it doesn't take up all your disk space.

Here's my thinking on this:

The system could be loaded into the first 80 to 100 GB of your first drive. That way it's always using the fastest part of the hard drive. Then the SWAP file could use the next portion, or the first portion of the second drive. Then the data file would use whatever portion on the second drive, and then be backed up on a not all-the-time basis to the latter portion of your first drive, so you're still getting use of it..

The other option would be, if wanting to buy more storage....
RAID1 of a couple small hard drives as mentioned by BBB, either 2 Velociraptors - small 80GB ones avail on eBay, or whatever. That way if the system fails, you're still good to go. Then RAID 1 for your data drives.

This would all work well and good for most purposes. The time when a RAID 0 would help primarily would be for media editing, especially video editing, and there especially if dealing with HD video, b/c you're dealing with huge files. In that case, it'd be nice/ideal to have at least 3 drives or RAID setups:
RAID1 system, RAID1 for data store, RAID 0 for editing... But then if you're getting into using at least 6 drives, you'd better be sure of your power supply.

Also, check the web on reliability of onboard RAID, particularly Intel Matrix RAID. I've read some pretty bad stories there. Still could be worth it, especially if you back everything up, but just keep it in mind. ;p

Then of course, you can always go to SSD for the system, and RAID1 the 2 640GB drives for your data...

The options are endless... a good thing and a bad thing at the same time.

Another cheap option is to look at the Samsung F3 drives to fill any additional drive needs. They're super fast, super quiet, and super cheap compared to the alternatives.

--

"If to err is human, then I must be some kind of human!" -Me

 

[kmcferrin]

Bearing in mind that RAID 0 gives you barely any performance boost is it worth it?

I disagree. I did some RAID1 vs RAID0 benchmarking a couple of months back just using the built-in software RAID in Windows 7 and a pair of 500GB WD Caviar Blue drives. The performance difference was significant, nearly double.

What I really want is a smart RAID controller that does two-disk RAID 10. Both disks are mirrors of each other but the data is still written in stripes so that when you read data it reads from both drives simultaneously. I know that the embedded SCSI controllers in HP and IBM blade servers do this, but I haven't seen this on the desktop yet.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCTS:Windows Server 2008 R2, Server Virtualization
MCSE:Security 2003
MCITP:Enterprise Administrator

 

[kjv1611]

kmcferrin,

I wonder if it could be at all possible with the Intel Matrix RAID controllers. I know they can do Mirrored and Striped on the same 2 disks, so I'd wonder if there'd be a way using what's already there to do the type setup you're mentioning..

I'm guessing no, not without Intel updating their firmware/software, but it's an interesting thought for sure. Maybe one day soon, that'll make it into the onboard setups?

--

"If to err is human, then I must be some kind of human!" -Me

 

[DorsetBunny]

My experience with RAID (both home and in enterprise env's) is to TEST TEST TEST.

Install a basic OS and some stuff on the arrays, then pull a drive and see what happens next. See how much recovery is possible and the details needed in order to manage it.

If possible - always document this, so you have an 'In case of failure' plan.

Yes testing this is a pain and very time consuming, but in the long run (that fateful day when a drive goes boom) you will be so very thankful that you took the time to plan ahead.

 

[FredWagner]

On RAID 10 - my impression is that it's for large arrays, and its advantage over RAID 5 is that it can handle more than one disk failure and still maintain service. RAID 10 on a two-disk system doesn't make sense to me....maybe I just don't understand it.

Fred Wagner

 

[kmcferrin]

On RAID 10 - my impression is that it's for large arrays, and its advantage over RAID 5 is that it can handle more than one disk failure and still maintain service. RAID 10 on a two-disk system doesn't make sense to me....maybe I just don't understand it.

It actually has several advantages over RAID 5:

1. It can survive multi-disk failures as long as only a single disk in any mirror fails.

2. It has faster write times than an equivalently sized RAID5 array due to no parity penalty.

And in the two-disk config,

3. You get the speed of RAID0 with the redundancy of RAID1.

________________________________________
CompTIA A+, Network+, Server+, Security+
MCTS:Windows 7
MCTS:Hyper-V
MCTS:System Center Virtual Machine Manager
MCTS:Windows Server 2008 R2, Server Virtualization
MCSE:Security 2003
MCITP:Enterprise Administrator

 

[FredWagner]

kmcferrin - thanks for the info!

Dorsetbunny - I'm with you - if it's going to be mission critical, we WANT to know what will happen when somthing fails - the true emergency is NOT the time to be learning.

this approach does carry over from my time in the USAF - in Bombers and liquid-fueled ICBM's

Fred Wagner

 

[rirusstek2]

I would like to thank all for the great advise and input about the RAID arrays.

I have a couple of questions:

http://img14.imageshack.us/img14/7113/raidquestion1.jpg

Issue #1 (white arrow)

I have a DP55WG board with an I7 860 Processor. I also have 4 SATA HDD two of them are set up as a RAID array (split up as RAID1 and RAID0) and the other two HDD as regular NTFS.

The main OS is on the RAID0 (Win7), everything is running fine.

On one of the other HDD, that are not in the RAID set up, I have a secondary OS setup (WinXP). This was setup before the RAID HDDs were added.

My question is: To access the OS (WinXP) on the other HDD do I have to change the BIOS System Setup - Configuration – Chipset-SATA Mode to IDE?

By doing this will I upset the RAID setup?

Can I go back to using the RAID0 HDD with the Win7 OS without any problems?


Issue #2 (Red Arrow)

On the Discrete –SATA Controller Configuration

Does this apply to the DP55WG Board?

The DP55WG board has 6 SATA ports (black) and the Discrete Ports are blue and they are 2 additional ports on the DP55KG board.

Would it then be OK to DISABLE this option (red arrow)?