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MSA20 >2TB Volumes?


MSA20 >2TB Volumes?

Looking to use an MSA20 with 12 x 500GB disks to achieve 5TB usable storage using Windows 2003 Server SP1 with GPT volumes. It seems thought, the SA controllers don't support a volume >2TB in size. :(

At the moment I'd be looking at creating 3 volumes (2TB, 1.5TB, 1.5TB) which is a big waste of storage as I'd want RAID5/ADG.

Any one got any ideas of whether SA controllers can go higher than 2TB volumes or a sensible cost effective workaround....?


Ivan Ferreira
Honored Contributor

Re: MSA20 >2TB Volumes?

The way I see this, you should waste the same ammount of space if you use one big lun or three luns with the same raid level. You will waste about 25% of the total space in RAID 5 for parity. The bigger the lune, the bigger the parity you will waste and it's more or less equivalent to 3*25% space used for parity.
Por que hacerlo dificil si es posible hacerlo facil? - Why do it the hard way, when you can do it the easy way?
Honored Contributor

Re: MSA20 >2TB Volumes?

I think Justin might be reffering rather to RAID arrays than LUNs. If you have three arrays instead of just one, you waste more space beacause an extra drive(s) is (are) required for each array.

I don't thik that 2TB limit applies to RAID5 though, but only to ADG:
"Advanced Data Guarding (RAID ADG) offers breakthrough level of fault protection of RAID volumes up to 2TB and a total of 28 disk drive in a RAID volume"

Bear in mind that:
a) the MSA20 has its own controller which maintains RAID operations (unless you connect it to the MSA1500)
b) ADG brings huge performance overhead, which could be especially painful when coupled with SATA drives (think rather about RAID 5 + hot spare)
Don't panic! [THGTTG]

Re: MSA20 >2TB Volumes?

Think I've solved my own problem :) just understood the array/logical drive concept...

1. Create a RAID5 or ADG array using all 12 500GB disks giving 5TB usable storage.
2. Then create several logical drives on that one array <2TB each.
3. In the O/S create dynamic GPT volumes and span them together.

Re: MSA20 >2TB Volumes?

Thanks for the replies.

It's going to be a DL360 G4p, with either a SA642 or SA6402 hooked up to the MSA20 with 12 x 500GB.

Based on the info on replies, I'll be best going with;

1. 11 x RAID 5 + 1 x Hotspare
2. Create 2TB, 1.5TB & 1.5TB logical drives
3. Configure the 3 disks in Windows as dynamic & GPT type and then span them together to get roughly 5TB as one volume.


Re: MSA20 >2TB Volumes?