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wolfh

8 Posts

9230

January 11th, 2005 11:00

AX100 Disk Groups & Virtual Disks

I have a Dell AX100 with 12x250 GB SATA Disks and one Server direct attached.
Whats the best configuration for maximum amount of disc usage ?
 
First Idea was to make one disk group with all 12 disks and make one huge Virtual Disk. This doesn't work because the maximum size of a Virtual Disc is 2 TB.
 
Any ideas, hints ?

Eric BY

2 Intern

 • 

815 Posts

January 12th, 2005 20:00

EMC recommends that you create a 4+1 RAID 5 configuration on the AX100. If you have a dual processor AX100, put 1 lun on A and 1 lun on B, then you a volume manager to combine the two luns into a single virtual disk. This will give you best performance.

big-wave-dave

21 Posts

February 1st, 2005 20:00

If I'm not mistaken, the AX100 supports RAID 5 and RAID 1.  RAID 1 is typically redundancy, whereas RAID 5 is redundancy with parity for error correction.  RAID 5 is more robust than RAID 1, but has more associated disk overhead because of the parity.  To get the absolute most disk usage, I would create 6 max size virtual disks (~500 Gb each) out of RAID 1 disk pools, where each disk pool is made up of 2 disks.
 
disks: 0, 1 -- raid 1 pool #1
disks: 2, 3 -- raid 1 pool #2
disks: 4, 5 -- raid 1 pool #3
disks: 6, 7 -- raid 1 pool #4
disks: 8, 9 -- raid 1 pool #5
disks: 10, 11 -- raid 1 pool #6
 
Just try to keep really heavy duty I/O off of pools 1 and 2 since (I'm pretty sure) the management software and SP OS resides on those disks.
 
// Correction!  I was misinfomed.  The AX 100 supports RAID 5 and RAID 1/0.  I don't know for sure, but I am willing to bet that RAID 1/0 (probably redundancy with striping) still takes up less disk space than RAID 5.  -bwd
 
By the way, even if the max Virtual Disk size were greater than 2 Tb, could your server address it?  If so, what kind of server is it, if you don't mind me asking?  I may have to get one of those someday...

Message Edited by big-wave-dave on 02-01-2005 05:07 PM

Dev Mgr

4 Operator

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9.3K Posts

February 5th, 2005 12:00

The AX100 running software version 02.08.100.xx.xxx only supports raid 5.

The newer software (02.16.x) adds support for raid 1/0 (and indirectly also for raid 1 as it allows a 2-drive raid 1/0, which effectively is a raid 1).

http://www.emc.com/products/systems/clariion/ax100/support/support.jsp

This site may be useful if you want to read more about the AX100's capabilities. There are release notes for the 02.16.x flare on there as well, which provide information on fixes and new features for the new flare.

Big-wave-dave is correct in stating that the first 4 drives (drive 0 - 3) contain the operating system for the AX100 (on a single storage processor AX100 it only needs the first 3 drives, but the 4th drive still cannot be a hotspare).

2 TB is the limit on any given LUN in any EMC Clariion (AX100, FC4x00, and CXx00) system that Dell offers. If you need a single drive letter (if you're using Unix/Linux you have various options for using mount points, so a 2 TB limit generally doesn't pose any limitations) with more than 2 TB of space, consider using Windows' ability to mount partitions into an empty folder (same idea as in Unix/Linux). The added space will only be available to data in that specific folder, but this way you can keep it under a single drive letter.

Message Edited by Dev Mgr on 02-05-2005 08:18 AM

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