Roger, I think that' not total correct. The speed of raid 5 depends of several things. Two of them are how big and sequential that write io's are. There are hardware vendors that implement raid 5 in their san very tricky: If the incoming data are "large and sequential" they are buffered by the san system in write cache until a full stripe can be written to all disks in a raid 5 group (typical 4+1). In this way a raid 5 is faster than a raid 1 since the write penalty is only 20% and not 50% as in raid 1. hope this was clear regards Stefan Holzwarth
________________________________ Von: ADSM: Dist Stor Manager im Auftrag von Roger Deschner Gesendet: Do 20.04.2006 19:00 An: ADSM-L@VM.MARIST.EDU Betreff: Re: SAN Disk for TSM diskpool for backups ? You will experience slower client backups with ANY configuration that is RAID5 for your disk storage pools. The reason is that client backup is 100% writes in the disk storage pools, and RAID5 is very slow at writes. The throughput difference is significant - as much as 75% in our case. After much experimentation, I have found that RAID1 is best for disk storage pools. Not RAID5, not RAID10, but RAID1. RAID5 can save you a little bit of money in disk drives, but you really pay for it in performance of something that is 100% writes. Roger Deschner University of Illinois at Chicago [EMAIL PROTECTED] On Wed, 19 Apr 2006, Justin Case wrote: >Need comments please reply.... > >We are going to be testing Apple Xserver raid disks array as the disks for >backing up the clients nightly backups >to diskpool. Has any one tried or even is anyone using the Apple Xserver >raid disks array for TSM server's diskpools >for nightly backups ??? > > >What raid is being used ? We are in the mind set to use RAID5 (5+1) with 1 >spare safety net and have a spare disks on site. >What issues have come up when using Apple Xserver raid disks array ?? >Any experiences that other TSM Admin's have had please reply with any >issues of success or problems ? > > >Thanks > >Justin Case >Duke University >