Re: SAN and dbspace layout.

Hi, I run Informix on EMC Symmetrix. Other than my storage guy giving me 2 GB chunks (because i have not turned on the large chunk feature), I don't care where he puts it. We have a lot of cache for EMC so chances are IDS is getting data from EMC cache and the application on top of IDS (which is SAP for me) gets it's data from IDS cache. In addition our SAP has plenty of cache. With cache up the wazoo, chances are the end users are getting data from cache be it SAP cache/IDS cache/EMC cache. My DB checkpoints happen to be double digits but do not make my customers scream. My checkpoints are high because we run EMC SRDF to our disaster site, without SRDF on, my checkpoints are usually under 3 seconds. While i don't care where my storage guy puts my chunks, I still care about defining dbspaces and managing them. Mostly i need to manage my dbspaces because of BACKUPS. I use onbar. the smallest unit of work for onbar is a DBSPACE. We use Veritas (I mean Symantec) Netbackup as our backup utility in hand with onbar. This does not change the fact that my smallest unit of BACKUP work is a DBSPACE. Onbar hands a dbspace to netbackup .... if the DBSPACE is 100GB, well, the amount of time it takes to backup a 100GB space is longer than a 50GB space or a 10GB space. So my dbspaces become a management issue for handling DB recovery. Remember the duration of your backup influences the amount of time you need to restore that DB (to a test system or egads after a failure). Before we changed out netbackup infrastructure a 50GB dbspace took 8 hours to backup. it did not matter that all 125 other dbspaces were 20GB or less.... the duration of my DB backup was still 8 hours because of that 50GB dbspace. (yup, multi-threaded backup with BAR_MAX... but all threads can finish well before the 50GB dbspace, but the 50GBer still marks the official end/completion of backup). In your case i would be concerned about sharing that SAN with other customers. Make the contract clearly state how much storage cache you get for DB and what performance (SLA - service level agreement) they adhere too. You are right to be concerned. your neck is on the line because you're the DBA.... and you need to know whose neck you choke at the SAN vendor (24x7 unless your DB doesn't need to be up 24x7). is the SAN vendor also providing the backups? if all they provide is the disk space and your employer is choosing to put a DB there....... who is responsible for backing it up/providing recovery/restores? interesting situation you are in. Norma Jean -- Message posted via DBMonster.com http://www.dbmonster.com/Uwe/Forums.aspx/informix/200610/1