Sign in with
Sign up | Sign in
Your question

Changing no raid to RAID 5

Last response: in Storage
Share
December 15, 2012 4:40:11 PM

I have a SSD for operating system, and a HDD for other stuff, including the "Users" folder.
I want to buy 2 more HDDs of the same kind and configure a RAID 5 setup for it. I'm thinking that it will be problematic since I have my Users folder on that drive, and I'm worried that it might mess up something related to that.
Is it even possible to switch to RAID 5 without the drive being offline, and if so, will it be difficult?

More about : changing raid raid

a c 97 G Storage
December 15, 2012 4:43:06 PM

nope. to build the RAID 5, all the data will be gone.
December 15, 2012 4:48:58 PM

I was thinking that I could configure RAID 5 with the two new ones, and make it act as the third one has failed. Then copy everything from the old one, format it and add it to the RAID 5. Is this possible?
Related resources
a c 86 G Storage
December 15, 2012 5:48:54 PM

You won't be able to set up the raid 5 without(at least) 3 good drives. It needs all the drives to set it up. so you won't be able to set it up with only 2 drives, and then add the 3rd drive.

How much space is used? You could back it up to an external drive first.
a c 86 G Storage
December 15, 2012 6:48:18 PM

1. for a raid5 you should always have a spare drive. so just by tree drives
2. raid5 IS NOT a replacement for backup! You should always keep a copy of your data.
a b G Storage
December 15, 2012 9:09:57 PM

norisak said:
I was thinking that I could configure RAID 5 with the two new ones, and make it act as the third one has failed. Then copy everything from the old one, format it and add it to the RAID 5. Is this possible?


This is actually a good idea and exactly how I migrated my RAID before I had devices which support RAID migration. If your RAID device supports creating degraded RAID (a RAID is degraded when it no longer offers redundancy), then this is a simple process and should work as intended. I think I read somewhere that a degraded RAID5 is simply RAID0.

Another option, if your device supports RAID migration, is to create a RAID1 array with the two new disks. After you copy your data, add the third disk and migrate to a RAID5.

noidea_77 said:
1. for a raid5 you should always have a spare drive. so just by tree drives


This is very good advice, but not a must. Having a spare drive enable quick recovery if there is a drive failure within your RAID array. With a three drive RAID array, your chance of having multiple disk failure at the same time is relatively small. My rule of thumb is to have a spare if the RAID5 array has at least 6 disk or switch to RAID6.

noidea_77 said:
2. raid5 IS NOT a replacement for backup! You should always keep a copy of your data.


This is very very important. RAID5 will not protect you from data lost. Also keep this in mind when proceeding with the suggested idea of starting with a degraded RAID5 array. You will be at a greater risk for data lost during the RAID rebuild (after adding the 3 disk to the array). RAID5 rebuilds are IO intensive (lots of disks r/w) and this increased IO could cause disk failure. If any of the two new disk in the degraded RAID5 fails during rebuild, you will loose the entire RAID array. Doing a RAID migration significantly reduces this risk (see above).
December 18, 2012 6:06:43 PM

ss202sl said:
You won't be able to set up the raid 5 without(at least) 3 good drives. It needs all the drives to set it up. so you won't be able to set it up with only 2 drives, and then add the 3rd drive.

How much space is used? You could back it up to an external drive first.

It's about 600 GB. But won't that mess up something with the Users folder that is on the old drive? I only have one User. Maybe it is possible to make a new temporary one?

Nothing_But_NAS said:
This is actually a good idea and exactly how I migrated my RAID before I had devices which support RAID migration. If your RAID device supports creating degraded RAID (a RAID is degraded when it no longer offers redundancy), then this is a simple process and should work as intended. I think I read somewhere that a degraded RAID5 is simply RAID0.

Another option, if your device supports RAID migration, is to create a RAID1 array with the two new disks. After you copy your data, add the third disk and migrate to a RAID5..

I have a MSI P67A-GD65 motherboard, and I've read that it has a build in raid controller that supports RAID 5, though I'm not an expert on this topic so it would be nice if any of you could confirm.
Also, how do I know if it supports creating degraded drives, and will there be any problems with the Users folder? I'm worried that something will go wrong there.
a b G Storage
December 18, 2012 7:22:41 PM

norisak said:
I have a SSD for operating system, and a HDD for other stuff, including the "Users" folder.
I want to buy 2 more HDDs of the same kind and configure a RAID 5 setup for it. I'm thinking that it will be problematic since I have my Users folder on that drive, and I'm worried that it might mess up something related to that.
Is it even possible to switch to RAID 5 without the drive being offline, and if so, will it be difficult?


Here is what I would do...

Get 3x HDD, build the RAID5
Test the RAID5 read/write speed and rebuid function.
Copy a 3~5GB file from/to you SSD to see the transfer rate
Unplug the HDD in middle of READ/WRITE
Wait for 15 seconds reinsert/connect the HDD back
Your RAID5 should be rebuilt

a_ If it rebuilds and trasferate is decent (over 100MB/s) - You are good to go!. Move your data over
Decommission the single HDD or use it as back up important data

b_ If it DOES NOT rebuild or having issue... look for alternative RAID5 solution
Hardware RAID is highly recommend - search the forum

There are plenty of my posts about the SPM393/SPM394 - cost effective hardware raid
!