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setting up a raid 5 system

aciddrops
aciddrops asked
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Last Modified: 2011-09-20
Hello i am thinking of setting up a raid 5 system using windows server.

I would have a HD for OS.  4 250G sata disks for raid 5.

my question is, if my OS HD fails, what happens to my Raid 5?  If i do a reinstallation  of the windows OS, will it be able to recognised the raid?

My concern is more data retention than performance since is a home storage network.

What other options are available for a home base raid 5?  Thanks
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Commented:
In case i am not too clear.  I am using windows software raid not hardware raid.
Lee W, MVPTechnology and Business Process Advisor
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Commented:
If the RAID 5 is on a seperate set of disks AND it's a SOFTWARE RAID 5 in Windows Server, then you would just have to import the foreign disks - the data should be fine.  If it's a HARDWARE RAID 5, then you only have to worry about it when the controller fails (IF it fails).

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Commented:
leew is absolutely on the money, just make sure you import them all at once

Commented:
Whay not set up the OS on a RAID1 array? THat way you get fault tolerance.

Mike
I agree with everyone above, but I have to ask...why software raid?  In my experience, it has not been very successful.  The over head of software raid and the hit in performance is undesireable.  I've seen more issues with software raid than hardware, tenfold.  You're only talking 200-300 bucks for a decent SATA Card, such as the one below:

LSI LOGIC MEGARAID SATA 150-4 4-PORT SATA/150 64MB RAID CONTROLLER ($238).

http://www.mwave.com/mwave/viewspec.hmx?scriteria=1275560

And that's considered to be a high end one, you can get a decent on for 100 bucks

http://www.mwave.com/mwave/viewspec.hmx?scriteria=AA25500

I would definitely consider putting in a card, if it is possible.  Maybe it's not.

Here's a link regarding software raid.  The Microsoft one talks a bit about the load on the CPU using Raid 5.

http://www.techimo.com/articles/index.pl?photo=149
http://technet2.microsoft.com/WindowsServer/en/Library/cb871b6c-8ce7-4eb7-9aba-52b36e31d2a11033.mspx


Good Luck!
Jim
Commented:
In first place, i agree that if you can afford to buy a harware solution it will be much better. But, if you dont, you can do your RAID 5 with Windows.

If you are running Windows 2003, you can go ahead with no problems. Windows 2003 version of NTFS has a copy of the RAID configuration - I think Windows XP NTFS is of same version. This information was found in Registry in previous versions.

Remember that you can build a RAID 1 (mirror) with the system files and build an aditional RAID 5 with the remaining disks. So, a suggested configuration would be:

disk 1 - OS (mirrored)
disk 2 - OS (mirrored)
disk 3 - RAID member 1
disk 4 - RAID member 2
disk 5 - RAID member 3

This way, you can use the full size of the disks 3, 4, 5 to create the RAID 5. I included a mirrored disk to avoid reinstallation, but you can live without disk 2.
Commented:
I don't see it mentioned anywhere, but add it just for safety: you can't boot from a software RAID-5.

If you want to use software-RAID, you will have to 'upgrade' them to dynamic disc. By doing that, Windows writes signatures to the drive to be able to recognize its contents no matter what happens to the OS.

http://www.petri.co.il/difference_between_basic_and_dynamic_disks_in_windows_xp_2000_2003.htm

Yes, your RAID-5 will be safe from an OS crash, but I have to agree on the fact that hardware-based storage is far more reliable and faster than software RAID.
To answer your question, you need to tell us how you plan to do your backup.

I typically backup using Ghost. In that case, the software RAID is a big pain as to do software RAID, Windows converts your disks to "dynamic disks".

Another problem is future expansion. PartitionMagic/VolumeManager does not work with dynamic disks.

My experience with this is that you need to avoid doing this at all cost - especially you are talking about a small cost.
I had a client's RAID 5 system hit with a massive power surge and when it failed, it took with it both the mirrored Raid 0 Boot Drives (which were hardware) and one of the 3 RAID 5 Software Arrays.  Lucky for her, that when I put toghether a new server, 2 of those 3 software arrays were good, just got some error messages and it was good to go.  Added a replacement drive and it rebuilt the entire array in a matter of about 4 hrs, while in use. (3 70 Gig Drives).  Definitely reliable, but defiitely slows down the system.  If performance isn't an issue, and you just don't want to spend the money on the hardware, go for it.  Your data WILL be safe, definitely safer than putting it on a single disk or even a mirrored set.

Author

Commented:
thank you everyone for your comments.

Author

Commented:
I am sorry i did not reply earlier.

i learned a lot from your comments.

i would likely to be doing

disk 1 - WD raptor OS
disk 2 -5 raid 5.
suggested by rmrustice.


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