AutoRAID Array Model 12H

[Jeffrey F. Goldsmith]

I have an AutoRAID 12H with 8 9.1GB 10K disk drives. I need to add 2 more drives to my system but I can only find 18GB disk drives. I was told that I could put the 18GB disk drives into my AutoRAID but am I going to have any problems with there being different drive sizes in the same AutoRAID?

[Insu Kim]

In the manual,
Disks of different capacities can be installed in the same array, providing maximum flexibility and expandability for your disk array. This makes it easy to increase your array's data capacity as new, higher capacity disks become available.

There is an important point to remember when using disks of different capacities in the same array.
You should add at least two high capacity disks to the array to use its full capacity.
If you add a single high capacity disk, the array will now be able to use its full capacity.
In this situation, the array can only use capacity equal to that of the largest disk already installed in the array.
Therefore, It should be no problem for you to add 2 more 18 GB disks to the array.

Hope this helps,

[Mark van Hassel]

Jeff,

If "Hot Spare" is enabled you will always "lose" diskspace when adding larger disks because the "Hot Spare" space will increase, in your case from 9.1 to 18.2 GB.

[Bill McNAMARA_1]

Filling out the field in the following link should work out exactly how much you should have:

http://www.hp.com/essd/capacity.html

Remember too, you're not really wasting space.. the hot spare is more correctly known as active hot spare in autoraid terms. The autoraid will store more data in raid1/0 for performance and on disk failure will guarentee that should the disk with highest capacity fail that it can shift enough data out of raid1/0 into raid5 (still protected but slower).

You can't shif from raid5 to another raid should another disk fail.. and in that case you're at N rather than N+1, you're data is still okay, but not your redundancy.

Later,
Bill

[Jeffrey F. Goldsmith]

Bill,
I went to the site that you gave me and entered my drive information to see how much space I will gain. I noticed that if I added 2 18GB hard drives to the 8 9GB hard drives that I already have I would only gain 16GB. If I am reading this right one of the 18GB hard drives is going to be used as a hot swap drive. That means that I have a hot swap drive with the 9.1GB hard drives and a hot swap with the 18GB hard drives. Is this correct?

[Dan Eastman]

We did it here at my shop. Yes you will loose some "space" to striping. We pulled out the old disk, gave the array time to rebuild which can take a while. Then installed the new disk. So far its chugging right along. Note that if you put in the 10K rpm disks, you will have to swap out the fan modules for the new high capacity fans.