I am not familiar with a Compaq solution (we use EMC), but they may have an optimizer or some way of identifying hot spots on disks and moving the data around to eliminate or minimize contention.
We took the approach of dividing up the partitions on the disks to small sizes to allow us more spindles on each LUN. This helps to improve performance and allows for more granular use of the disks. Example if you go with 50 GB partitions the smallest portion you can increase by is 50 Gb we use 9 GB so that we can set up on 9 GB partitions. Just another opinion. Take it as you will. -----Original Message----- From: Chris Levis [mailto:[EMAIL PROTECTED]] Sent: Friday, October 04, 2002 10:27 AM To: NT 2000 Discussions Subject: RE: Basic SAN question Thanks for the warning. I do plan on minimizing the number of LUNs, but my boss asked the question and I wanted to be sure to have the /right/ answer instead of the /right-now/ answer. > -----Original Message----- > From: Roger Seielstad [mailto:[EMAIL PROTECTED]] > Sent: Friday, October 04, 2002 7:51 AM > To: NT 2000 Discussions > Subject: RE: Basic SAN question > > > 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.unsub%% > ------ You are subscribed as [EMAIL PROTECTED] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to %%email.unsub%% This e-mail and any files transmitted with it are confidential and are intended solely for the use of the individual or entity to whom they are addressed. If you are NOT the intended recipient or the person responsible for delivering the e-mail to the intended recipient, be advised that you have received this e-mail in error and that any use, dissemination, forwarding, printing, or copying of this e-mail is strictly prohibited. ------ You are subscribed as [email protected] Archives: http://www.swynk.com/sitesearch/search.asp To unsubscribe send a blank email to [EMAIL PROTECTED]
