Basic RAID question

[DougMcDonald]

Hi all,

I have two physical drives, and I'm contemplating setting up a raid array (curiosity more than anything).

What I wonder, is this:

If I partition each physical drive into two equal size logical chunks, say 100GB for OS and 300GB for Storage; can I setup two raid arrays (RAID 0 for the OS, which I would be prepared to lose in event of a hard disk failure) and RAID 1 for the storage, so that would be mirrored in the event of failure.

A) Is this possible?
B) If yes, would i need to use hardware (on the P5B) or some software method?
C) Is it a stupid idea! would i do better just getting a third drive and using RAID 5 to offer what I'm trying to achieve.

Cheers,

[pauldarkside]

Two RAID solutions using only two drives?

The short answer is no. Typically, a RAID controller uses physical drives not volumes. Your partitions would be lost once you've configured your RAID array. You're free to create partitions after you've created your array as the OS will generally only see the array’s volume and not the drives making up that volume.

I use a RAID 0 solution (minimum of two drives) for my things like the OS, applications, games, etc; all types of data I'm prepared to lose. RAID 1 (minimum of two drives) for storage and backups; data I can't afford to lose.

To make the most of redundancy, i.e. your mirrored solution, you really ought to use identical drives with similar wear and tear.

[EtheAv8r]

Hi all,

I have two physical drives, and I'm contemplating setting up a raid array (curiosity more than anything).

What I wonder, is this:

If I partition each physical drive into two equal size logical chunks, say 100GB for OS and 300GB for Storage; can I setup two raid arrays (RAID 0 for the OS, which I would be prepared to lose in event of a hard disk failure) and RAID 1 for the storage, so that would be mirrored in the event of failure.

A) Is this possible?
B) If yes, would i need to use hardware (on the P5B) or some software method?
C) Is it a stupid idea! would i do better just getting a third drive and using RAID 5 to offer what I'm trying to achieve.

Cheers,

Your motherboard has I believe the Intel ICH8/9R with 6 SATA ports on the Intel controller?

Then the answer is yes. You can run Intel Matrix Storage Manager, and 2* 500GB HDs would allow a RAID 0 of say 256GB for C: and OS etc, and a 377GB RAID 1 for data – providing resilience in the event of HD failure.


Is it stupid? I do it and so do lots of others. Maybe we are stupid!

[pauldarkside]

Interesting, I hadn't thought about using the console to mix RAID modes using the same array. I'm not sure I like the idea though.

I'd be interesting in seeing performance data that compares it to a dedicated RAID 0 and RAID 1 using identical hardware, especially in terms of accessing data on both volumes concurrently. I wonder how much performance gain, create by using RAID 0, would be lost in that kind of mixed mode configuration?

[pauldarkside]

One downside to this though is that mixed mode RAID volumes would need to created within the OS. How easy or possible is it to transfer this array to another system, with or without an Intel controller?

[DougMcDonald]

I wonder how much performance gain, create by using RAID 0, would be lost in that kind of mixed mode configuration?

I wondered this too, maybe I'll try and see what happens

The reasoning behind this would be that I would like to see if RAID 0 would have a noticable performance increase, but wouldn't want to tie up both drives with no recovery option if one dies, so would like the RAID 1 option for resiliance.

Currently I just have two drives working as master and slave (2 os installs at the moment (testing XP64)) and i suppose if my data drive died, I would still lose the lot, so RAID 0 on the whole drives doesnt really have any risk apart from maybe losing everything even if one drive dies.
Is it possible to recover a RAID 0 config if only one drive dies? I wouldn't have thought so without the use of a parity drive and therefore different raid config. Can anyone shed any light on this one?

Your motherboard has I believe the Intel ICH8/9R with 6 SATA ports on the Intel controller?

Yeah, thats the controller. I thought it may be possible, but was not sure.

EtheAv8r - Would you be able to provide any info on how to do this? Ideally a high level step by step.

Is it as simple as using the matrix manager and it's all done in there? do i need to format and partition using, say, a windows setup process?

Being very new to this, I would assume that process would be:

- get the matrix manager thing and setup partitions/raid configs as desired
- install os (is there anything i need to take into account here? boot disks etc)
- rejoice at the spanky new config

[DougMcDonald]

Peripheral question here. The Intel Matrix Storage Manager was mentioned.

I went to the intel site, downloaded the driver and attempted to install....only to be met with:

'This computer does not meet the minimum requirements for installing this software'

Two part question really:

1. Is the software incompatible with XP64? I hope not since Intel asked me to select OS before download.

2. Do these kind of RAID driver installs fail without having anything attached/configed to the RAID controller.

I tried to use the Jmicron thing that was on the P5B mobo CD, but that tells me: 'JMicron Raid device not found'

Do i need to do anything specific to activate it? It's sat in hardware manager with no problems, and is enabled within BIOS

[EtheAv8r]

EtheAv8r - Would you be able to provide any info on how to do this? Ideally a high level step by step.

Is it as simple as using the matrix manager and it's all done in there? do i need to format and partition using, say, a windows setup process?

Being very new to this, I would assume that process would be:

- get the matrix manager thing and setup partitions/raid configs as desired
- install os (is there anything i need to take into account here? boot disks etc)
- rejoice at the spanky new config

Yes I will get back to you - with all the info you need. Off to bed now (up ay 06:00 for work).

[EtheAv8r]

Peripheral question here. The Intel Matrix Storage Manager was mentioned.

I went to the intel site, downloaded the driver and attempted to install....only to be met with:

'This computer does not meet the minimum requirements for installing this software'

OK this is a mini Catch 22. You cannot install the software (which also includes drivers) because the system is not set to RAID and there are no suitable drivers installed. If you had built the system and hit F6 and installed the relevant drivers with the OS, then the software would install OK.

Two part question really:

1. Is the software incompatible with XP64? I hope not since Intel asked me to select OS before download.

Yes there are 32bit and 64 bit versions of Intel Matrix Storage Manager

2. Do these kind of RAID driver installs fail without having anything attached/configed to the RAID controller.

You attach your HDs to the Intel ICH8/9R regardless of whether they are RAID or just standard IDE/SATA - you set this up in the BIOS by setting the controller to RAID, and subsequent RAID setup configuration.

I tried to use the Jmicron thing that was on the P5B mobo CD, but that tells me: 'JMicron Raid device not found'

JMicron is not involved here, we are using the ICH8/9R controller

Do i need to do anything specific to activate it? It's sat in hardware manager with no problems, and is enabled within BIOS

Yes indeed, but it is not difficult.

Firstly I will describe my setup:

I have five SATA hard disks (HD) in total plus a SATA DVD writer so all six ports on my Intel ICH8R controller. I am not using the JMicron controller for HDs, but do have IDE DVD Writer so have loaded the drivers.

Four of the five HDs are identical 500GB HDs, and the fifth is 320GB.

Two of the 500GB drives are paired in a RAID Array, with the first 256GB volume being RAID 0 and is the C: (System) drive with Windows OS, most applications and general stuff, and the remaining 377GB is a RAID 1 volume and is the E: (Backups) drive. So there are two physical HDs in the array, and it has two volumes, a RAID 0 volume (created first so it takes the outer and faster cylinders) for speed/performance and a RAID 1 volume for resilience. If a drive fails I still have the data on the E: drive accessible, but the system on C: is trashed. I don’t care about this as I have backups and restore a working bootable system from an image in a few minutes.

The other two 500GB drive are also paired in a second RAID array, again with the first 256GB volume being RAID 0 and is the D: (Sims&Scenery) drive with Flight Sims scenery and some programs, and the remaining 377GB is a RAID 1 volume and is the F: (Data) drive.

So I run the OS from the C: and use the F: drive for data – as they are on physically separate HDs, performance is excellent. My documents (on the C: drive) is automatically replicated to a Server, but I keep photos, music, backup images, important docs etc on the F: (Data) drive. Most, if not all the F: Drive contend is replicated to the E: (Backups) drive so I effectively have 4 copies of my important data stored on separate HDs.

The fifth G: (Recovery) drive has another install of Windows, plus a bunch of utilities, benchmarks, evaluation and testing stuff etc. and I can boot to this for recovery or testing purposes so I keep ‘rubbish and ad-hoc’ stuff off my ‘operational’ system on the C: drive.

So that is the environment and as you can see you can have two separate RAID volumes on one physical pair of HDs as a two disk array – and there are other options with more drives in the array if you want. I believe it is a very safe way to operate. And Intel Matrix Storage Manager seems to work well.

It is possible to create a RAID array integrating a currently installed HD with Windows on it, and for experimental purposes I tried it to confirm it works and it does. However for me at that time the currently installed OS was my 320GB HD and I wanted to run my RAID off the 4 new 500GB drives, so I build that from scratch, which is possibly a bit easier.

All you do for that is install the HDs, go into BIOS and set controller from IDE to RAID, boot from Windows Installer CD, Hit F6 and load RAID Drivers, during POST hit Ctrl/I and configure the RAID 0 volume and then proceed to install Windows on that volume. You then install the Intel Matrix Storage Manager (I use 7.5.0.1017) and can subsequently configure the rest of the RAID setup with that or via Ctrl/I at startup.

If you need detailed instructions, I can provide them.

[DougMcDonald]

Brilliant info, thanks a lot.

I suspected the catch22 type situation may be to blame for things not working.

I will follow you instructions as per the first two drives you describe.

Just going through the backup of anything important at the moment.

Annoyingly im stuck in Scotland until tomorrow lunchtime, but I'll see if I can config it in an afternoon, doesn't seem too taxing, I'll post any updates back here :]

Final question, this JMicron thingy, I have 1x SATA DVD and 2x SATA HDD's, I have until recently kept the Jmicron thing disabled, but will I likley need it as a component in this config?

I would have thought not, but maybe it's worth checking. I don't actually know what it does, but would assume that if using the ICH8/9R controller that it would be surplus to requirements.

Any info on this one?

[EtheAv8r]

JMicron covers the EIDE/PATA and the eSata ports (possibly the floppy controller - not sure on that one). It will not figure in your Intel matrix Raid, which is on the 6 ICH8/9R ports. Dont forget to craete you F6 Floppy with drivers before you start.

Check out this tread, http://forums.hexus.net/showthread.php?t=112584 for details on 'converting' using existing HD, and other useful info - post 21 was my experience and has some useful links.

The link to the downloads may be of use, but the one to the excellent Intel guide is essential - it will tell you everything you need to know.

[master811]

Interesting, I hadn't thought about using the console to mix RAID modes using the same array. I'm not sure I like the idea though.

I'd be interesting in seeing performance data that compares it to a dedicated RAID 0 and RAID 1 using identical hardware, especially in terms of accessing data on both volumes concurrently. I wonder how much performance gain, create by using RAID 0, would be lost in that kind of mixed mode configuration?

I saw somewhere they did a comparison of a separate Raid 0 and Raid 1with the IM Raid 0/Raid1 and the performance difference was pretty much negligible.

http://techreport.com/reviews/2005q1...d/index.x?pg=1

have a look through there, they basically conclude that there is no downside to using IM raid. The only problem you will have is if you try accessing data from both Raid 0 and 1 on the IM arrays at the same time, as the disk heads will have to access both at the same time, so copying data from raid 0 to 1 or vice versa etc, but generally I think the benefits would outweigh the problems. (mentioned here http://www.techarp.com/showarticle.a...tno=206&pgno=1 )

[mroz]

Thanks from me too. I'm building a new system soon & this info is just what I need before deciding how many drives I require. Cheers

[pauldarkside]

Good links master811.

It seems to me that IMR, or practically any other software RAID solution for that matter, is ideally suited to those seeking performance and redundancy on a budget. Like partitions, IMR will suffer when accessing data on both parts at the same time.

It should have been obvious really

[DougMcDonald]

I have just finished the dual raid array install with only two drives, and the performance does indeed seem increased.

Interestingly I get mixed performance ratings from HD Tune and HD Tach, tune tells me I can only get 69 MB a second, whereas tach says I can hit 110 or so (on the raid 0 array)

The raid 1 array is giving me 65MB a second-ish, which suggests HD Tune can only read the raid 0 array at the same speed at the raid 1 array. This implies that potentially some of the benefits could be negated by having the two on a single pair of physical drives.

I will do some more testing tonight if i get time and see what happens.

Overall though, the answer to the initial question is yes - two raid arrays can exist on two physical drives.

[EtheAv8r]

I have just finished the dual raid array install with only two drives, and the performance does indeed seem increased.

Interestingly I get mixed performance ratings from HD Tune and HD Tach, tune tells me I can only get 69 MB a second, whereas tach says I can hit 110 or so (on the raid 0 array)

Oh in this situation I tend to go for the most optomistic figures - makes you feel better Same with weather forcasts, of one gives rain and another gives sunshine, I go for the one with sunshine LOL. I did comparative testing with HD Tune, running it on the single stand-alone HDs first and then again on the RAID arrays. I saw about 25-30% improvement on the RAID 0 performance and about the same performance on RAID 1 as the single disk. Interestingly a 3 disk RAID0 saw another 25-30% improvement but a 4 disk RAID 0 did not improve on that.

The raid 1 array is giving me 65MB a second-ish, which suggests HD Tune can only read the raid 0 array at the same speed at the raid 1 array. This implies that potentially some of the benefits could be negated by having the two on a single pair of physical drives..

Yes indeed - this is why I have two arrays (0 + 1) on two pairs of disks, so that most of the time I am using either the Raid 0 on one physical pair with the RAID 1 on the other, or bothe RAID 0's (Flight Sims).

I will do some more testing tonight if i get time and see what happens.

Overall though, the answer to the initial question is yes - two raid arrays can exist on two physical drives.

I thought we had already confirmed that one - I have been doing so successfully for a few weeks, and Supershanks has been doing it for months.

I do look forward to your further test results....