I give you Wanda's favorite answer, "It depends." Concepts: * Primary storage is the repository where you keep data for normal backup/archive and restore/retrieve. You can have a disk only primary storage. You CAN have all disk storage. There are lots of discussions on ADSM-L about it
* Some environments use disk storage for the initial landing point for backup/archive data. That is a Primary Pool. >From there they migrate data to another pool in the hierarchy, perhaps tape or virtual tape. When the data "migrates" it moves off of the first primary storage pool onto the NEXT primary storage pool. It is still Primary storage, just on different media. That is not a Copy Pool. * If all you have are Primary pools, you have backed up data, but it isn't safe. * Copy pools are a backup (second) copy of the data that reside in Primary pools. The "backup stgpool" command makes a thorough copy of the Primary StgPool. Often copy pool data on removable tape is taken out of the library daily and sent offsite for disaster recovery. You can mix media and it's purpose in many combinations to suit your situation. You can go straight to tape...NDMP used to only work that way. You can use: Pri-Disk backedup to Copy-Tape (sounds like your plan A) Pri-Disk migrated to Pri-Tape backedup to Copy-Tape (sounds like your Plan B) Pri-Disk backedup to Copy-Disk and migrate each of them to tape, one to Pri-Tape and the other to Copy-Tape. Pri-Disk migrated to Pri-Tape and backedup to Copy-Tape. TSM will allow you to write to write simultaneously to Primary and Copy storage pools (but you still need to run storage pool backup.) ( http://pic.dhe.ibm.com/infocenter/tsminfo/v6r2/index.jsp?topic=%2Fcom.ibm.itsm.srv.doc%2Ft_simulwrite.html ). Two tape drives is a tight squeeze. It is the bare minimum for doing tape reclamation. You have to have time for daily client data migration to primary tape, client data backup to copy tape, TSM db backups, any db snapshots, restore activity, and tape reclamation. So, "it depends": You asked if it is a good idea to have a Primary tape and Copy Tape storage pool. Is your system part of a larger business continuity/disaster recovery plan, or is TSM it? How much data do you backup every day? 9TB of data feeding into a TS3100 seems a little mismatched. I work with TS3310 and TS3500 (3584) libraries. I don't have any experience with the TS3100. Glancing at it on google it looks very small. If you do a backup stgpool for your primary disk pool, you need as much space as is in the primary pool. If you also have a primary tape pool (primary disk migrated to primary tape, copied (backed up) to copy tape) you need just as much more storage. If you are removing the copy pool media regularly (daily, weekly) then you don't need too much more library space than your primary pool requires, but you need some more...which depends on how much your data changes and how often you eject copy media and how many scratch you keep in the library. How long do you retain your data? How long does data stay in the disk level of the hierarchy before it migrates? Do you do a lot of restore/recover or is that an infrequent task? What throughput do you have on your tape drives? Could you get another tape drive or two perhaps? Would it be efficient enough to use less disk and more tape? If you don't restore a lot, and or don't restore a lot of really large objects (db files, entire filesystems and such) then maybe less disk would be more cost effective. You can't compensate for insufficient tape drive capacity by adding more disk (been there!). So the answer is, yes, that's a good plan, having tape primary and copy pools behind a disk primary storage pool, but you need to consider your tape capacity. and whether you need all that disk. Anyone else please chime in. I am still wrapping my mind around thinking past being an admin. I am sure I have overlooked things I might have added. You can go here to look up old threads: http://adsm.org/lists/html/ADSM-L/ George Huebschman (George H.) (301) 699-4013 (301) 875-1227 (Cell) The contents of this email are the property of PNC. If it was not addressed to you, you have no legal right to read it. If you think you received it in error, please notify the sender. Do not forward or copy without permission of the sender. This message may contain an advertisement of a product or service and thus may constitute a commercial electronic mail message under US Law. The postal address for PNC is 249 Fifth Avenue, Pittsburgh, PA 15222. If you do not wish to receive any additional advertising or promotional messages from PNC at this e-mail address, click here to unsubscribe. https://pnc.p.delivery.net/m/u/pnc/uni/p.asp By unsubscribing to this message, you will be unsubscribed from all advertising or promotional messages from PNC. Removing your e-mail address from this mailing list will not affect your subscription to alerts, e-newsletters or account servicing e-mails.
