Michael, I would choose 2. Using JBOD disks build a cachepool with enough space for incrementals. With the rest of it built on RAID5, create onlinefile with devclass file. Choose a volume size of 25GB and create all the volumes manually rather than having TSM create them for you on the fly. This way you avoid fragmentation.
You might also choose to use all devclass file pool space and send data directly there instead of using the cachepool. I would decide to do it that way if I didn't have lots of clients backing up simultaneously as that pattern is very hard on a RAID5 array. Finally, I would target only that data that would really benefit from this type of storage. Probably file servers or the like. I wouldn't use it for large things, probably, like databases or Exchange data. That will restore just as fast from tape as from disk. We routinely build our STORServers with a complete mix: cachepool JBOD on fast disk, onlinefile RAID5 or relatively slower SATA disk, and onlinepool LTO4. With this you can optimize both backups and restores. One last thing: you really need to use devclass file on the bulk of the storage as the disk device class does not provide space reclamation with the file device does. Thanks, Kelly Lipp CTO STORServer, Inc. 485-B Elkton Drive Colorado Springs, CO 80907 719-266-8777 www.storserver.com -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Michael Green Sent: Friday, November 14, 2008 3:19 PM To: [email protected] Subject: [ADSM-L] Best use of disk storage Bright minds, If you are given 20T of disk space, how would you use it in TSM 5.3 environment in context of speeding up restores? 1. Would you create large disk pools with CACHE=y or.. 2. Would you create disk pools sized to accommodate routine incrementals only with the rest of the space dedicated to devc=FILE stgpools for staging? (i.e. building a hierarchy such as disk -> file -> tape) -- Warm regards, Michael Green
