setting up raid-5 questions

[csmaster2005]

ok I'm thinking I'm going to setup 4 hard drives on raid-5

Now, I am going to do this via my motherboard, a DS3R (if anyone knows the performance on doing this I wouldnt mind hearing aobout it)

My question is this: First, raid-5 doesnt require all the hard drives to be the same size, so I was wondering how would I find my 'useable' amount? Lets say for example I have 2 300 gig hds, 1 400 gig hd, and 1 500 gig hd. (I plan to just buy 2 more 300 gig hd's so I have 4 300 gig hd's for 900 gigs of useable space, but wanted to know this anyways)

My second question is, am I able to setup raid-5 on a hard drive that already has everything installed on it? Meaning, I already have vista installed on this hd and alot of other programs installed etc, and would PREFER not to have to reinstall everything, will raid-5 take care of this for me? (my main question is what is the hd requirements to set this all up?)

Third, after I setup raid-5, will it all just show as 1 big 900 gig hd, or will it show individual drives, or is it I must setup partitions so it shows as independent drives?

Thanks!

 

[xitshsif]

1. Depends on the controller. Most onboard controllers will just do the minimum of all. So you'd have 900 gig of usable space with those 4 drives.
2. You will need to reinstall everything. You're essentially formatting a large volume.
3. You'll have a single 900 gig drive.

 

[Fullmetal Chocobo]

RAID 5 usable size = gb*(n-1), where gb is the size of each disk, and n is the quantity. The -1 is due to the parity calculations being stored.

I highly suggest having another disk for boot, but that's just me. It makes setup so much easier, and if you have to replace, reinstall, or upgrad the OS, you can do so independently of the RAID 5 array (when I reformat, I unplug all disks so that there is no chance of corruption. After the reinstall, install the RAID drivers, plug in the drives, and I'm good to go).

 

[csmaster2005]

so what if I had hd's that are different sizes?

What if I setup the raid then at a later point I want to add a hd to the setup... will I need to reinstall the array again?

 

[cmbehan]

Originally posted by: csmaster2005
so what if I had hd's that are different sizes?

What if I setup the raid then at a later point I want to add a hd to the setup... will I need to reinstall the array again?

If your disks are different sizes, your RAID controller will only use an amount equal to the smallest disk from each drive. In your case: 300+300+400+500=1.5TB, but because the smallest disk is 300gb, you will only get 900gb of storage in a RAID 5.

As far as adding a disk to the array, it depends on your controller. Some of them can add capacity and re-build on the fly, but they're expensive. In the vast majority of cases adding a disk means starting completely over.

 

[Fullmetal Chocobo]

Originally posted by: csmaster2005
so what if I had hd's that are different sizes?

What if I setup the raid then at a later point I want to add a hd to the setup... will I need to reinstall the array again?

Then it will create an array with the smallest hd size. So if you have 2-80gb hds, 2-120gb hds, and 1 200gb hds, there will be an array of 5 80gb disks, with a total usable gb of 320gb. Some controllers and setups can use the left over space (such as the extra 40gb left over on the 120gb disks) and Intel Matrix RAID might be capable of that as well. I'm not too sure, as I haven't messed with it. Best thing to do in this case is to consult the manual for your RAID controller to find out it's capabilities.

 

[Madwand1]

Which DS3R? Maybe it doesn't matter, but there are a couple of different ones with that suffix. Assuming it has a ICH9R or similar southbridge, then:

1. RAID 5 performance should be good when write caching is enabled
2. You can't use the extra space on mismatched drive sizes
3. RAID 5 expansion features are basically non-existent
4. You might be able to do an in-place conversion from a single drive to RAID 5

But, this gets trickier due to the fact that the OS would now have to to boot with RAID 5 underneath it instead of a single drive. You just shouldn't try this without an external backup.
You'd also need to expand the file system after the array is expanded. Again you shouldn't do stuff like this without a backup. (Unless you're willing to lose everything of course.)

Oh, and "RAID alone is not a backup".

RAID 5 is better than nothing, but is not as good as an external backup. On-board RAID 5 will also use more CPU than single drives. I agree with Choco's recommendation of keeping the OS separate from the storage / RAID for maintenance reasons, and it might also help performance -- by putting less load on the system for general access; by taking less of the RAID 5 performance hit in some cases, and by allowing the possibility of true concurrency / seek avoidance when you're accessing stuff off the OS drive and RAID array concurrently.

 

[csmaster2005]

hmm I guess I could install the OS onto a seperate drive. Is there anyway to set the OS to instead of defaulting to the my documents on the hd, to use my documents location elsewhere? (like on the raid array) and same with other basic windows locations?

Also, installing programs to a different drive shouldnt have any real loading issues correct?

Madwand - I didnt quite understand what you meant by #4.

also my mobo is http://www.newegg.com/Product/...x?Item=N82E16813128050

have you heard anything about raid for it? Also my CPU is a e6750, so I shouldnt really have any issues with the raid using cpu resources correct?

 

[Madwand1]

Your motherboard has an Intel ICH9R RAID implementation. By #4, I mean that Intel doesn't provide any features for adding drives to an existing RAID 5 array. I'm not even sure if you can expand an existing array by replacing all the drives one by one with bigger drives (rebuilding the RAID 5 array after each drive substitution). I'm sure you could replace all the drives, but I'm not sure that you could use the new space in an existing array. You should be able to use the new space one time for a new Matrix RAID array though, assuming you don't already have two arrays on the same drives.

Install the Intel Matrix Storage Manager (or whatever it's called now), and look at the Help for details on configuration and conversion options.

The CPU load is not going to be a big deal on modern CPUs, but it is a hit, especially when writing to RAID 5. Just something you might want to be aware of when considering your options -- by putting the OS on a simple drive, you'd avoid some of those hits.

Decent installers let you pick the drive to install your programs. You should be able to move the Documents folders, but I haven't done this myself, so don't know the details at the moment. It could be as simple as a copy and environment variable change, but you should look this up somewhere.

 

[Fullmetal Chocobo]

Yes, you can change the location of 'My Documents'. Just right click on it, go to properties and click on 'move'. After selecting the new location, it will ask if you want all of my existing files in your old location moved to the new location.