SQL Server Performance Forum – Threads Archive

How to Carve a SAN

Hello Guys, We are going to host 12 large DB, 150GB + each, they will be hosting on a SAN that contain 9 VLUN which make up of 36 * 150GB disk drives. For Disk I/O subsystem performance, would it help if we create 72 LUNs and put each type of data files on each LUN. For example
LUN1 = VLUN1, VLUN3, VLUN5, VLUN8 for Reference Datafile
LUN2 = VLUN3, VLUN4, VLUN7, VLUN1 for Indexes Datafile
LUN3 = VLUN2, VLUN8, VLUN0, VLUN1 for App Type A Datafile
â€¦ for App Type B Datafile
LUN72 = VLUN0, VLUN2, VLUN3, VLUN6, VLUN5 for historical Datafile
any help will be highly appreciated. Thanks ~K

I’ve moved to relevant forum.
Luis Martin
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the VLUN is very bad for performance critical databases
it is also absolutely essential for each high volume database to have dedicated physical disks for the log. normally 2 disks in RAID 1 is sufficient, however SAN drives generally have poor sequential performance, so 4-6 disks for the log is better. figure 10MB/sec for each pair, then determine how many disks you need for each multiple databases can share disks for the data file, but low latency transaction db should share one pool, while DW apps should share another. the other criteria is that the data files should be able to sustain > 300MB/sec, preferably >700MB/sec, test this with a table scan returning few rows, this is so that a large query does not shut down transaction processing capability.

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