During Oxford 2005, IBM stated that the File Device Class is the strategic data structure. One can see this in action with the dedup functionality in V6.
Our products use DISK for cachepool usually deployed on JBOD arranged FAST disk (SAS or FC at 15K) as the initial target for client backups, particularly for large numbers of clients with small data movement. File Device class is used for large amounts of storage (since we can have reclamation there). Our pools are targeted by clients moving a lot of data daily, or are the target of migration from the cachepool. I think both are still valid for the reasons already described but in the long run DISK may go the way of the dinosaur. Kelly Lipp CTO STORServer, Inc. 485-B Elkton Drive Colorado Springs, CO 80907 719-266-8777 x7105 www.storserver.com -----Original Message----- From: ADSM: Dist Stor Manager [mailto:ads...@vm.marist.edu] On Behalf Of David McClelland Sent: Monday, September 21, 2009 9:52 AM To: ADSM-L@VM.MARIST.EDU Subject: Re: [ADSM-L] the purpose of "file" device class Just to be uber-picky, FILE volumes now do allow multiple sessions/processes to read/write concurrently to a single FILE volume from TSM 5.5 onwards (http://publib.boulder.ibm.com/infocenter/tivihelp/v1r1/topic/com.ibm.itsmms munn.doc/anrsgd5515.htm#wq28). The big picture as I've read it is that IBM are perhaps angling the user-base towards using FILE volumes, and that new developments would be implemented against FILE technology rather than DISK. That being said, it's fair to say that many people are simply more comfortable with the ease, simplicity and habit of implementing and managing DISK volumes. /DMc -----Original Message----- From: ADSM: Dist Stor Manager [mailto:ads...@vm.marist.edu] On Behalf Of Shawn Drew Sent: 21 September 2009 15:58 To: ADSM-L@VM.MARIST.EDU Subject: Re: [ADSM-L] the purpose of "file" device class Disk Based (Random access) lets you have several sessions all sending data to it. This removes the need to queue backups like all the competitors. But it will fragment as data expires and there is no defrag for random access. File devices (Sequential access) do also fragment over time, just like tape, but you are able to run reclamation on them. But sequential access would cause queuing. They each have different pro's and con's which make them suited for different tasks. (long term vs short term storage) Regards, Shawn ________________________________________________ Shawn Drew This message and any attachments (the "message") is intended solely for the addressees and is confidential. If you receive this message in error, please delete it and immediately notify the sender. Any use not in accord with its purpose, any dissemination or disclosure, either whole or partial, is prohibited except formal approval. The internet can not guarantee the integrity of this message. BNP PARIBAS (and its subsidiaries) shall (will) not therefore be liable for the message if modified. Please note that certain functions and services for BNP Paribas may be performed by BNP Paribas RCC, Inc. No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.409 / Virus Database: 270.13.109/2384 - Release Date: 09/20/09 06:22:00