Chris, Most vendors will allow you to slice and dice a SAN array into as many LUNs of whatever size you want. Its absolutely the wrong thing to do, but it certainly can be done.
Any time a phisical platter is partitioned, you're going to take a performance hit - simply put, the heads can't be in two places at once, so if two systems are trying to access data which is physically on the same platter, but logically on different LUNs, there is head contention, and one of the two must wait for the other to finish "using" the heads, and then pay the additional price of a head seek across the platter to its assigned set of cylinders. In the case of your single 500GB RAID5 set in your SAN being split into 300/100/50/50, you have in reality created 4 partitions on each spindle, with 60%/20%/10%/10% split on each spindle. With a large number of platters, and larger stripe sizes, its theoretically possible to reduce the chances of contention within the SAN, but realistically speaking, chances are there is going to be some contention, and therefore some performance hits associated with managing your disks this way. Its one of the lies^H^H^H^H omissions commonly done in the sales pitches of the big storage vendors. ------------------------------------------------------ Roger D. Seielstad - MCSE Sr. Systems Administrator Inovis - Formerly Harbinger and Extricity Atlanta, GA > -----Original Message----- > From: Chris Levis [mailto:[EMAIL PROTECTED]] > Sent: Thursday, October 03, 2002 2:07 PM > To: NT 2000 Discussions > Subject: Basic SAN question > > > If you have a RAID-5 array of (let's say) 500GB, can you > create LUNs of an > arbitrary size to be presented to the servers? E.g, a 300GB, > a 100GB, and > two 50GB? Or is there a convention that all LUNs have to be > a uniform > size? > > Thanks! > > > > > > ___________________________ > Chris Levis > Applied Geographics, Inc. > > ------ > You are subscribed as [EMAIL PROTECTED] > Archives: http://www.swynk.com/sitesearch/search.asp > To unsubscribe send a blank email to %%email.unsub%% > ------ You are subscribed as [email protected] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED]
