RAID 5 question...

[redman71]

I've got 7 hot swapable drives in my server. Two configured with RAID 1 and the rest with RAID 5. All are 40G a piece. However, I'm running out of disk space. Therfore, I'd like to replace 4 of them with 120G drives. Does anyone see a problem with this?

 

[rvnguy]

You can always upgrade HD size/speed.

Make sure to complete a backup first.

??you currently have 5 40GB drives as raid5....why only 4 120's?

If you attempt to RAID5 4 120's & one 40...you will be limited to 40GB per drive in the RAID config. Save xtra 40 for some other use.

Just insure that the 120's are of the same interface you are currently using and you will have to rebuild the array then restore the data. Other than that no real issues.

rvnguy
"I know everything..I just can't remember it all

 

[redman71]

So all the drives in the RAID config have to be the same size? Also, how does the 120 drive get the info from the 40's? Doesn't at least one 40 have to be mounted for the 120 to rebuild from?

 

[stduc]

You'll have to either do a full backup & restore after swapping the disks & rebuilding the RAID from scratch - or build a new RAID.

You can't increase the capacity of a RAID by simply swapping in larger disks.

Or can you? I have never tried. But I suppose, providing you have a good backup, it would be worth trying.

I'm wondering, if you swap out one disk for a new and larger one - the RAID should re-build. You repeat with the next disk, and so on until the whole RAID is on the new drives. At that point is it possible to either re-size the partitions, or add a new partition?

Now - if you like to live on the edge! - Not recommended though. LOL

 

[rvnguy]

So all the drives in the RAID config have to be the same size?

Yes & No..........you can have disimilar drive sizes but you will then have an array at the lowest common denominator....
i.e. 2 80's & 1 60....=array of 60 excess space can be another volume but not part of a raid 5 array. I assume you desire the redundancy of raid5....

Doesn't at least one 40 have to be mounted for the 120 to rebuild from?

one 40 from your old array does not contain enough data to rebuild from,,,remember raid5=striped+parity.

Bottom line:to get the increased volume size you are seeking:
1. backup your data
2. remove the 40's
3. install the 120's
4. enter raid setup at post setup raid5 on these drives
5. you now have raid5 on 4 120GB volumes that contains no data
6. restore data to this array from your backups
7. done

rvnguy
"I know everything..I just can't remember it all

 

[redman71]

Great...thanks!

 

[redman71]

Another qutestion...
Here's my setup...Have 12 slots, only using 10
(9) 36.4G drives in RAID 5
(2) 36.2G drives in RAID1

Is there someway I could bread the RAID 5 up into 7 drives in RAID 5 and add two additional drives (larger disks) to make 3 more in RAID 5?

I know it sounds off, but just wanted to know if it can be done to save $$.

Thanks

 

[Freestone]

redman71

Your first and last posts are confusing, at least to me, as to the number of drives your server actually has installed.

Your first post states 7 drives, two of which are in a mirror set, thus leaving 5 in RAID5 configuration.

Your last post says you have 12 drive bays, of which 10 are populated. (9) 40GB drives in RAID5, and (2) 40GB drives in RAID1. That adds up to 11 drives.

If I interpret correctly, you currently have one empty bay, so you want to remove two drives from the current RAID5, thus leaving 3 empty bays for an additional RAID5 composed of newer, larger drives.

Can your RAID controller handle more than 2 defined arrays? I would think so, but you want to be sure it can.

Would you clarify the number of bays and the number of populated bays?

 

[redman71]

Freestone,

Sorry for the confusion. My last post was right. I had to check the drives. I've got 12 bays and 11 are populated. I think my RAID controller can handle it. I'd have to check though.

 

[Freestone]

So you will remove two drives from your current RAID5, losing 80GB. You will add 3 drives to created another RAID5 array, but gain only 2 drives worth of space as the other drive's worth of space will be used for parity. If you add 120GB drives, your net gain will be 2*120 - 80, or 160GB.

You can assess your net gain using other drives sizes in the new RAID5 array. Just remember that a RAID5 array capacity is (number of drives in array - 1) * drive capacity.

 

[Freestone]

I forgot to add that if you do plan on proceeding with removing 2 drives out of your current array, you must back up your data prior and create a new array, as stduc and rvnguy have mentioned earlier.

 

[rvnguy]

Whose controller make & mdl are you using?

As freestone stated it must support multi arrays or you can install another controller but that gets sticky, possible just more complicated.

If you have more time than funds you can do this

Post back with card info....

BTW do you require the redundancy provided by raid5?

rvnguy
"I know everything..I just can't remember it all

 

[clarkdo]

I have 4 identical servers - each has three 18.2GB drives in a raid5. One of the servers has failed - data totally wiped out. Can I rebuild that server by putting one drive from the failed server into one of the good servers and letting it rebuild and then repeat for the second drive and then repeat for the third?

 

[rvnguy]

clarkdo,

First, you should have started a new thread....

But now that you are here...

No, you cannot rebuild from one drive...

You state that the data totally wiped out???
How have you determined this??
If totally wiped why would you think that you could rebuild from it?

Raid5 requires 2 drives to rebuild from, as the theory goes 2 drives will not fail at the same time ergo the failed can be rebuilt from the other two.

What you described is replicating one drive oa a set of 3. Note 'set' ...therer are two that are striped and one that is the parity drive with bits of data spread between them.

Did the server fail? the Array controller? the power supply or exactly what was the failure?

rvnguy
"I know everything..I just can't remember it all