Multiple raid configurations on a single set of drives?

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Travisty2012

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Mar 20, 2007
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I have an ASUS P5W DH Deluxe using the ICH7R chip to raid 0 two WD 160 gig drives.

Can you, or does it make sense to, setup different raid drives with these two drives?

For example. These two drives yield about 300 gig after formating. What if I did 100 gig at raid 0 for the C drive, then took the remaining 200 gig and formatted it in raid 1 which would give me a 100 gig D drive. Then I could keep a copy of the C drive on the D drive as a backup.

I'm going to add a couple 500 (maybe larger) gig drives in the future for a raid 1 disc to store all my music, movies, pictures. I know I could keep the backup on this, but doing it on the 160's would leave more room for my media. Plus I'll never fill the 300 gig raid 0 because I only plan on using it for the OS and stuff I can re-install. It wont matter if I lose it...but if I had a backup copy it would make recovery easier.

Am I making sense? Can you do what I'm asking? Would it even help?

Thanks
Travis
 
Hi, I'm curious about this as well. I'm thinking about the same setup for my system. I think it uses something called Intel Matrix to do the multiple RAIDS on the same discs.

I'm curious to know how the performance really stacks up compared to either doing the 2 RAIDS on separate physical HDs, or even just the difference between using 2 seperate drives (OS & Data) without any RAID?

The HDs obviously only have one arm to read/write data at once. So doing anything on the 2 seperate RAIDS (the OS & the Data) would have to take a performance hit.

Looking for a way to get the performance setup usually used in a DAW setup (separate OS and Media drives) but with SOME sort of redundancy or security of a RAID.
 
Yeah, to not take a performance hit I'm sure you would need the raid arrays setup on different drives. I'm not really worried about a performance hit because I would only be using both during a backup...for which I wont be staring at the monitor waiting for it to finish.

My main concern is how to rebuild it. Say you just have a few clusters get screwed up on one drive, as long as I can boot to windows I can copy the missing data back to the C drive. BUT, if one of the drives fails completely, even if the D drive was in Raid 1 I don't know how it could be rebuilt?
 
Can you, or does it make sense to, setup different raid drives with these two drives?
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no and it makes absolutely no sense whatsoever.

valis

What doesn't?

I know it's possible...

ODU1.gif

Storage Advisors

I just don't know HOW...and more importantly, how to recover from a failure.
 
You can do what you're asking. Whether it makes sense or not is a different question altogether. I have a matrixed array of RAID 5 and RAID 0. I use the RAID 5 for O/S, programs and sensitive data, so that I don't have to restore from backups after a failure. I use the RAID 0 for very temporary storage (e.g. temp directories), where I don't care if they survive the night.

When there is a failure, I can still boot off the RAID 5 array. I see the failure, swap out or reconnect the disk (I've done this a couple of times due to connectors falling out during other intra-case work), and both RAID volumes become available again. If you use your RAID 1 as a backup, it might make sense to make sure it's bootable so that you have an easier way to get in and figure out what's going on. Not sure if you can do that without mirroring your RAID 0, which would incur a major performance penalty for writes.
 
If you use your RAID 1 as a backup, it might make sense to make sure it's bootable so that you have an easier way to get in and figure out what's going on. Not sure if you can do that without mirroring your RAID 0, which would incur a major performance penalty for writes.
Click to expand...

Oh, good call making the backup bootable. I wouldn't want to set it up as a true mirror anyway. Like I said, everything on C is going to be OS stuff and programs etc. that I can reinstall...but would be more convenient if I had a backup. I could just mirror it once a week or so.

What program would I use to take some of my RAID 0 and turn it into a second RAID 1 drive? Just use that Intel Matrix storage program? Then what would be a good program to mirror the drive? If I mirror it, will it be bootable or are there extra steps? Hmmm...more stuff to play with.
 
Except I want mine to look like this:

446114289_12e807fb21_o.jpg
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you aren't thinking clearly.

raid 0 is striping
raid 1 is mirroring

with raid 1 you have a storage "hit", meaning you have two 160 gig drives, but in raid 1 configuratino you will only have 160 gig after the raid is created, you get 1/2 of what you put in. it's what you pay for fault tolerance. if one drive goes, you have a mirrored backup. that's the point of raid 1

so you have two 160 gig drives, you have to deal with physical DRIVES not partitions here, if you make 4 partitions, two on each drive, for simplicity lets say you cut them down the middle, two 80 gig partitions each, ending up with a b c and d partitions

two 100 gig drives in raid 0 = 200 gig
two 100 gig drives in raid 1 = 100 gig

you could conceivably stripe a and c , giving you a 160 gig raid 0, if you mirror (raid 1) the other two partitions you'd have one 80 gig drive letter, two 80 gig partitions in a raid 1 = 80 gig, not 160.

you'd end up with 240 gig

i dont think you'd see enough of a speed increase because the controller doesn't have access to the full drive, it's doing mirrored writes and reads at the same time and using the SAME DRIVE HEAD that it's doing striped writes and reads. it's best to use seperate drives for this. get two 60 gig drives, stripe them, use them for OS, get two 160 gig drives, mirror them for your safe data.

Valis
 
http://www.acnc.com/04_01_00.html

read here for more information on raid levels
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I understand RAID...I think you are a little confused.

I have two 160 gig drives. Let's just call them 150 after formatting.

Take 50 from one and 50 from the other and make a RAID-0 drive and call it C:. This would be a 100 gig drive.

Then take the remaining 100 from the first and 100 from the second and make a RAID-1 drive and call it D:. This would be a 100 gig drive.

So the result would indeed look like this:
446114289_12e807fb21_o.jpg


The final result is 200 gig total. Laying it out this way makes sense because the only thing on D is going to be a backup of C. So they should be the same size...

Now, I just make D: a mirror of C: and make sure it's bootable. Mirror it once a week or so. If something fails, change the boot drive to D, reboot and rebuild...

EDITED:
In the pictures, the colors represent one partition spanning multiple drives. I'm only talking about making 2 raid partitions with 2 physical drives.

Also, when I say mirror, I don't mean real time mirror. I mean use a utility once a week or so to make D a mirror copy of C. C is going to be nothing but OS and other programs I can re-install. I don't really care if I lose it. Now, I'll never fill up the whole thing since I don't have that many programs to load, so I might as well try and make use out of it. If I can make recovery quicker/easier than reinstalling everything, that would be a good use. If I could just replace a drive, copy the mirror from D back to C and be done with it, that would be a lot quicker than re-installing everything and re-tweaking all the programs...
 
Also, when I say mirror, I don't mean real time mirror. I mean use a utility once a week or so to make D a mirror of C. C is going to be nothing but OS and other programs I can re-install. I don't really care if I lose it. Now, I'll never fill up the whole thing since I don't have that many programs to load, so I might as well try and make use out of it. If I can make recovery quicker/easier than reinstalling everything that would be a good use. If I could just replace a drive, copy the mirror from D back to C and be done with it that would be a lot quicker than re-installing everything and re-tweaking all the programs...
Click to expand...

!@#$!@#$!@#$ then you aren't talking raid! you're just talking about making a regular backup, which is what you should be doing. raid IS a REAL TIME mirror of two drives or partitions.

maybe this will help you:

http://www.pugetsystems.com/articles?&id=29
Why RAID is (usually) a Terrible Idea excerpt:
So what do I have against RAID? I have no problem with the concept. The problem is that for 90% of the people out there, it isn't a good idea. Since high end enthusiast machines are some of our most common builds here at Puget, we frequently are asked to build machines with RAID when it doesn't make sense. I am here to say that those RAID configurations account for a very large portion of our support tickets, and are one of the biggest sources of frustration for our customers. I can also tell you that "I told you so" is not a very comforting reply from our support staff! Don't worry, that's not what we say (but there are times when we sure do think it!). That is the root of my problem with RAID -- I see the frustrations it causes all the time. When I weigh that against the benefits of RAID, I just can't recommend it except in very select cases.
Click to expand...
 
!@#$!@#$!@#$ then you aren't talking raid! you're just talking about making a regular backup, which is what you should be doing. raid IS a REAL TIME mirror of two drives or partitions.
Click to expand...

You still don't understand what I'm doing.

Given:
1) I currently have two 160 gig drives in RAID 0 for my OS / installable programs.

2) I don't care if I lose them as I can re-install everything, it will just take a long time.

3) I will never fill up this 300 gig drive with OS / programs. Lets assume the most I will ever use is 100 gig of this drive.

4) Regardless of all the arguments you can make, I like RAID-0 for my OS to make loading times quicker. Please no discussion on this...

Goal:
1) Make a backup of the current drive so that in the event I do lose it I can recreate the drive quicker than re-installing / re-tweaking everything.

2) Use only the existing equipment

3) Make use of the extra room on my drive as I will only use 100 gig anyway.

Solution:
1) Use 50 gig from each drive to form a RAID-0 C drive used for all my OS / programs. This works as I have previously stated I will only use 100 gig anyway.

2) Use the remaining 100 gig on each drive to make a RAID-1 D drive.

3) Use a utility program to mirror the C drive to the D drive once a week.

4) Make D drive bootable.

5) In the event of a failure, I lose C. I can restore it because it because I have a recent copy on D which is in RAID-1 so it should survive the failure.

REMEMBER:
1) I've already said I don't care if I lose C. I can re-install everything. The goal of this setup was to shorten the recovery time from re-installing everything to just copying a few day old mirror, while making use of hard drive space I wouldn't use otherwise.


Are we clear now?
 
You can do exactly what you want to do with the Intel Matrix RAID controller. It fully supports this configuration.

However, I think you may want to look at a bit different idea for what you would want to use this for. The general idea behind a combined RAID-0 & RAID-1 setup is that you would use the RAID-0 for the OS, your games & programs, and maybe scratch disk for something like Photoshop. The RAID-1 is used for your documents, music, pictures, etc. -- anything that you want protected from hard drive failure.

You could do periodic backups of the partition(s) on the RAID-0 logical drive to the RAID-1 drive, but it kind of negates the benefits of having the separate RAID-0 & RAID-1 portions. In your situation, you say that in the near future that you're going to get other drives to hold your data files like music, pictures, etc. In that case, you have virtually no data to store on the RAID-1 partition, so the usefulness of the RAID-1 is minimal. Also, the backup of C: that you would store on the RAID-1 would be some kind of image backup, which would never be bootable, so that idea is out. You would need to boot from some kind of recovery CD and re-image the C: partition once the failed drive was replaced.

If I were you, I would set this up as follows:

Logical Drive 1: 60GB RAID-0, holding 1 partition, C:. OS, programs, games, scratch disk.

Logical Drive 2: 100GB RAID-1, holding 1 partition, D:. Extremely important data, documents, pictures, etc.

Logical Drive 3: Other, single large drive (internal or external), holding 1 partition, F:. Bulk data - music, movies, etc. Also can hold a periodic image backup of C: for quick recovery.

Logical Drive 4+: Other, single large drives if necessary for more space.

One idea for imaging the C: drive to one of the large drives is to use DriveImage XML. It can make a compressed image of your C: drive, and can do it while Windows is running (unlike Ghost). And it's free.

Also, a few other tips so that we keep the discussion in order:

1. RAID controllers make logical drives out of physical drives. In the Intel Matrix RAID case, it can make multiple (up to 2) logical drives using fewer physical drives than other controllers, which can be useful. Don't call logical drives "partitions". Logical drives are set up in the RAID controller BIOS.

2. Partitions are segments of drive space set up with a file system. Windows can create multiple partitions on the same drive. Partitions are set up in Windows Disk Management. (Thus it is conceivable that you could have theoretical partitions C: & D: on the RAID-0 logical drive (say if you wanted to separate OS/programs/games from scratch/pagefile), and partitions E: and F: on the RAID -1 logical drive (say if you wanted to separate business documents from music).
 
You could do periodic backups of the partition(s) on the RAID-0 logical drive to the RAID-1 drive, but it kind of negates the benefits of having the separate RAID-0 & RAID-1 portions. In your situation, you say that in the near future that you're going to get other drives to hold your data files like music, pictures, etc. In that case, you have virtually no data to store on the RAID-1 partition, so the usefulness of the RAID-1 is minimal. Also, the backup of C: that you would store on the RAID-1 would be some kind of image backup, which would never be bootable, so that idea is out. You would need to boot from some kind of recovery CD and re-image the C: partition once the failed drive was replaced.
Click to expand...

I guess this would only work if I can make my backup on D: bootable. I want D to be a mirror (not real time, mirrored once a week) and make it bootable.

Currently this is my new computer so I only have XP installed and a few games to play around with. My old computer has all my pictures / music / etc. on it. Before I bring this data to the new computer I was going to setup two more drives in RAID 1 for this. Now, I realize I can save a compressed backup of my C drive to this but the goal was to use the unused space on the RAID-0 to make a backup and free up more space on the other drives to still be used just for pictures / music / etc...

Now I realize the smarter thing would of been to go with a mix of RAID 0 and RAID 5 from the start. Use 4 or 5 drives and make a RAID 0 with small portion of the drives for my OS. Then use the remaining space for a RAID 5 to hold all my pictures / music / etc. AND a compressed backup of the RAID 0 drive...

BUT

I would rather not waste these 2 160 gig drives I just bought. I should of got 4 or 5 identical larger drives from the start...
 
Say I forget the above idea and go with a new plan:

ODU1.gif


Say I get four 320 gig drives...call them 300 after formating for simplicity sake.

Take 25 gig from each drive and make a RAID-0 C drive to use as an OS / programs drive. It would be 100 gig.

Then you have 4 drives left with 275 gig each. Put these in a RAID-5 setup which would yield a 825 gig D drive. Use this for all the important data AND a compressed backup of the C drive.

Now, say one drive fails. You are obviously going to lose the C drive. How do you recover? You can't boot from C and your backup should be safe on D. Does the RAID utility give you some kind of boot disc? So you would replace the drive, use the boot disc to restore the drives? Then reinstall windows on your blank C drive. Then install your backup program and then use that to load your backup back onto C.

Is that correct?
 
it probably is possible with that chipset, but I wouldnt do it, because a lot of the time it wont rebuild one of the arrays during failure and you need to reinstall anyway.
 
I guess this would only work if I can make my backup on D: bootable. I want D to be a mirror (not real time, mirrored once a week) and make it bootable.

...

Now, say one drive fails. You are obviously going to lose the C drive. How do you recover? You can't boot from C and your backup should be safe on D. Does the RAID utility give you some kind of boot disc? So you would replace the drive, use the boot disc to restore the drives? Then reinstall windows on your black C drive. Then install your backup program and then use that to load your backup back onto C.
Click to expand...

Well, first: A once-a-week backup is not a mirror. The word "mirror" is reserved only for real-time mirroring of data as a RAID-1 does. If the backup is once-a-week, then it's a backup, not a mirror.

Now, I know of no program that can make a once-a-week backup to another drive automatically, and make the backup drive bootable as well. (There are offline/manual solutions like Ghost or Partition Magic that can copy the partition to another drive and it'll be bootable, but that's a manual process, not automatic).

My question is, why does the backup of the C: drive have to be bootable? What's wrong with an image backup as long as you can restore it?

We have multiple, somewhat conflicting purposes here: You want RAID 0 for your boot drive, I assume for speed. You're not going to store anything on that RAID 0 that isn't recoverable (i.e. only OS, games, programs), so reinstallation is possible. But you also want to be able to easily recover the C: drive should it fail.

Here's how an image backup scenario would work:

1. Say you've got 2 physical drives, RAID-0 space for C:, RAID-1 space for D:, no other drives in the system.
2. Use DriveImage XML to schedule images of C: to D:. Not going to be very fast, but will work.
3. Drive fails at some point. Replace failed drive.
4. Intel controller rebuilds the RAID-1 portion of the drives. RAID-1 data (D: ) is intact and re-mirrored. Go into Intel RAID controller BIOS, recreate RAID-0 portion which will now be blank.
5. Boot system from a BartPE CD-ROM with the DriveImage XML plug-in. Using stored backup image on D:, reimage C:.
6. Boot from C: and all is restored.

Now, if you're considering going 4 drives, there's an easier way: Use RAID-10 for the C:, RAID-5 for the D:. Now both partitions are redundant and can handle a drive failure, and the RAID-10 is as fast as the RAID-0. Now you don't need to image anything. Here's the failure scenario:

1. Drive fails, shut down machine.
2. Replace failed drive. Intel controller starts rebuilding both logical drives.
3. You can boot and work with the machine during the rebuild.
4. After rebuild is completed, everything is restored. No backup image needed or used.
 
Whether you go with RAID 1 or RAID 5 for your backup, if it stores an image of your RAID 0 array, can it not also still be bootable? In other words, install the O/S to that logical drive, install your drive backup-restore utility into that second O/S install, and then store your C drive images there. I'm not sure if you can boot from two logical drives from Intel Matrix (I haven't tried), but I believe you can. You don't need the second drive to mirror the first, as long as the second is bootable and has an image and utilities you can use to restore the first drive.

That said, I would recommend using RAID 5 instead of RAID 0 for programs and such, because for the WORM usage model, RAID 5 works VERY WELL. You get the benefits of easy recovery, as well as the benefits of striped performance for reads. Writes are slower, but that's less of an issue when you are writing only once. My HTPC boots uberfast b.c. of the RAID 5 array for O/S.
 
1. Say you've got 2 physical drives, RAID-0 space for C:, RAID-1 space for D:, no other drives in the system.
2. Use DriveImage XML to schedule images of C: to D:. Not going to be very fast, but will work.
3. Drive fails at some point. Replace failed drive.
4. Intel controller rebuilds the RAID-1 portion of the drives. RAID-1 data (D: ) is intact and re-mirrored. Go into Intel RAID controller BIOS, recreate RAID-0 portion which will now be blank.
5. Boot system from a BartPE CD-ROM with the DriveImage XML plug-in. Using stored backup image on D:, reimage C:.
6. Boot from C: and all is restored.
Click to expand...

How does the Intel controller rebuild an array? Say you had a failure and you replaced the drive. The next time you boot up, do you hit CTRL-I (or whatever the key stroke is to enter the Intel Storage Matrix) when booting and select a repair option?

If that was the case, you could rebuild the array. Then switch the boot drive to D, boot into the backed up OS, copy the backup back to C and then reboot into C. I'm not familiar with BartPE / DriveImage XML. I guess I was using a bootable D / backup instead where you would use BartPE...

I really only wanted to make recovery of a failure quicker than re-installing everything...
 
1 TB RAID 5 4d array: O/S, programs, pictures, music, video, and other data I want to have some redundancy for, and doesn't change often. (hence my ID: "Tera(byte)Media")

125 GB RAID 0 4d array: temp directory, page file, and working directory for transcoding for media xfer to PDA. Very fast for reads and writes. According to Toms it can get up around 240 MB / s, but I have never clocked it.

930 GB RAID 0 2d array: TV recording. I originally had this on a RAID 10 array where the 125 GB array is currently sitting, but 60 GB was not enough to record for very long. Also, the drive heads were thrashing and slowing everything down so I was dropping frames. Then I changed to the 125 GB RAID 0 array. Performance improved, but I was still getting occasional disk thrashing, and 125 GB also is not much for storing OTA HDTV. It's only enough for ~15 hours. Then when a 400 GB drive failed, I ordered the two 500 GB drives with the intention of eventually upgrading the whole 4d array. But the 400 was eventually recovered (connector problem, not a drive problem), and I was able to use the 500s instead for TV recordings. No more dropped frames, and I can support 2 analog and 1 HDTV tuners recording while I watch recorded HDTV locally and recorded analog via an extender. And at 3.1 GB / hr for analog, 8.x GB /hr for digital, I can record between 100 and 300 hours of shows - enough for an entire season of a couple of different series plus a movie-on-demand library.
 
Hi, I'm very interested in this conversation since I have 2 x 160gb HD's myself and was just thinking of doing something like that.

My question is this: Isn't raid 1 supposed to give you higher read performance? if that is so, wouldn't it be more useful to have your os and important data in raid 1 (since there isn't much writing in it) and make a small partition of raid 0 only for processing data (like video or audio) and non important or temporary files?

I hope I'm not making a fool out of my self by asking this, but as they say in my country: "he who doesn't ask, doesn't learn". :?:
 
RAID 0 will read almost twice as fast as RAID 1 for large files, because the data is divided across the two disks rather than being copied on both. I imagine a super-clever driver could get equivalent performance by striping the read requests, but I don't know of any such driver, and certainly not the Intel Matrix Storage drivers.

RAID 0 of course is missing redundancy though... so if you're limited to 2 internal disks then RAID 1 may be the only way to achieve redundant storage. And it will make it easy to recover without having to reinstall a bunch of stuff.
 
RAID 0 will read almost twice as fast as RAID 1 for large files, because the data is divided across the two disks rather than being copied on both. I imagine a super-clever driver could get equivalent performance by striping the read requests, but I don't know of any such driver, and certainly not the Intel Matrix Storage drivers.

RAID 0 of course is missing redundancy though... so if you're limited to 2 internal disks then RAID 1 may be the only way to achieve redundant storage. And it will make it easy to recover without having to reinstall a bunch of stuff.
Click to expand...

thanks man, I thought that "super-clever driver" that "could get equivalent performance by striping the read requests" in RAID 1 was something that existed and that was so normal, any driver could do it. If you ever know of one, please don't hesitate on telling me.
 
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