Expanding an existing disk pool with different types of hard drives

Hi All,

I have a question I believe I already know the answer to but was hoping that I could get a few other opinions on the matter.  We are currently looking to fill up the rest of our SAN enclosure and I was looking to possibly go with larger hard drives this time around.  We currently have an enclosure half full of 300GB drives which was divided into multiple disk pools setup in RAID 5.  My question is, would it be possible to add 450GB hard drives to fill up the rest of the enclosure and be able to expand an existing RAID 5 Disk Pool or would a new Disk Pool have to be created due to the fact that the hard drives are of a different size.  I know with a desktop or workstation this would be the case but I was unsure if this was something that perhaps the SAN would be able to get around.  Any feedback or input would be appreciated.  

EMC Clariion AX4-5
LVL 1
crphdAsked:
Who is Participating?

[Webinar] Streamline your web hosting managementRegister Today

x
 
Duncan MeyersConnect With a Mentor Commented:
> My question is, would it be possible to add 450GB hard drives to fill up the rest of the enclosure and be able to expand an existing RAID 5 Disk Pool or would a new Disk Pool have to be created due to the fact that the hard drives are of a different size.
Yes, you can add 450GB drives to fill the enclosure - no problem there. You'll need to create a new disk pool and use metaLUN expansion to add space from the new pool into existing LUNs. There's more information here: http://www.emcstorageinfo.com/2008/03/type-and-benefits-of-meta-lun.html and here (with a how-to): http://blog.scottlowe.org/2009/10/23/how-to-create-a-metalun/
0
 
naldiianCommented:
If you want to directly expand your RAID 5 array, you would lose the additional size from the new drives, meaning you would add 450 GB drives and only get 300 GB per disk out of them since the RAID striping would only expand across the equivalent amount of space from the old drives.
That said, if this is a SAN enclosure, adding space and expanding a LUN can be done in several ways, so what the best solution option is depends on your intended use of the additional space and the supported disk pooling capabilities on the SAN device. You could just add the additional disks and make them their own RAID array, but still use the space in various manners in coordination with the original disks and capacity. You should not need all of the disks in the enclosure to be one single array in any but the lowest-end SAN appliances.
0
 
Duncan MeyersCommented:
Alternatively, you could add the drives as a RAID Group expansion and teh left-over space on the 450GB drives will be available for use - but it's a very slow process. Using metaLUNs is faster and more efficient.
0
 
Duncan MeyersCommented:
Thanks! Glad I could help.
0
All Courses

From novice to tech pro — start learning today.