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DavidDay22
28 Posts
0
14561
December 18th, 2007 19:00
MD3000
I have an MD3000 with 15 146G 15K drives, with 2 controllers. I have this setup with 1 drives as a hot spare, 2 drives a RAID 0, and the other 12 drives setup as RAID 1 (actually this becomes RAID 10 I believe). The performance from the RAID 10 array behaves like write caching is not enabled, is putting 12 drives in as RAID 1 really the same as RAID 10?
DavidDay22
28 Posts
271
0
Posted December 19th, 2007 12:00
I am building a SQL server, and I plan on using the RAID 0 for tempDB. I can't find where to set the cache policy for the RAID controllers, like I do for a regular PERC card (read ahead, writeback, etc.)When I benchmark the two drives I created, the two drives in RAID 0 and the 12 drives in RAID 10 have almost identical results, leading me to wonder if the limiting factor is something to do with the HBA throughput.- My first recommendation would be to read the SQL Deployment Guide for the MD3000i (see the following link). Although the host-to-array interconnect described is iSCSI the array RAID disk group configuration applies as well as the the back-end cabling.Also see the main Dell SQL page ( www.dell.com/SQL) for more good information.For virtual disk cache parameters on the MD3000 see this guide:
DavidDay22
28 Posts
271
0
Posted December 29th, 2007 12:00
"The core architecture of the PowerVault MD3000i and the PowerVault MD3000 are very similar. Both
storage systems feature dual RAID controllers, share a common RAID engine, and provide support for the
same number, type, and speed of hard-disk drives. In fact, the primary difference between these two storage
systems lies in the ports that are used to connect host servers to the array. While each MD3000i RAID
controller features two GbE host ports, the MD3000 controllers feature two SAS x4 wide ports."
Since these arrays are so similar, why would the iSCSI interface provide higher IO/s, but lower MB/s?
Dev Mgr
6 Operator
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9308 Posts
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3 Points
271
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Posted December 19th, 2007 11:00
Sidenote: Why did you select to use a raid 0? Is it just for testing/comparison? Even if the data is completely 'missable', I wouldn't use raid 0 due to the hassle involved with the host's OS and the time involved with getting the virtual disk back available to the host.