Hi Richard! Tapes aren't read from the beginning either, so why should TSM do so for file volumes? A tape is wound to the closest data marker and from that point, the read starts. Although a VTS simulates tapes, the read mechanism seems to be much faster. We are currently starting with testing a EMC DL700 disk library. From other users I heard that the combined volume mount and position to data (seek) times are always less than a second, no matter where the data is located on the virtual volume. Kindest regards, Eric van Loon KLM Royal Dutch Airlines
-----Original Message----- From: Richard Rhodes [mailto:[EMAIL PROTECTED] Sent: Monday, June 20, 2005 13:47 To: ADSM-L@VM.MARIST.EDU Subject: Re: File dev. type vs. VTL One of the things I've wondered about VTL's and file devices is how they handle seeks. What happens when TSM needs to access a file that's at the end of a vtl "tape" or file volume? For a file device, does TSM open the file and read the entire volume till it gets to the file or is tsm smart enough to seek closer to the file. If it has to read the entire volume then this is an argument for smaller file volumes. For a vtl - same basic question. Since a vtl emulates tape drives, I assume tape marks have to be recorded. I wonder if a vtl indexes the tape marks so it can seek directly to a mark on disk. Rick "Loon, E.J. van - SPLXM" To: ADSM-L@VM.MARIST.EDU <[EMAIL PROTECTED] cc: M.COM> Subject: Re: File dev. type vs. VTL Sent by: "ADSM: Dist Stor Manager" <[EMAIL PROTECTED] .EDU> 06/20/2005 06:56 AM Please respond to "ADSM: Dist Stor Manager" Hi Dough! We choose a VTL over a file device class because several reasons: 1) IBM couldn't provide us a reference site with a 100 TB. + file device class. 2) We were not sure how AIX would handle a crash with several very large filespaces. How long will a filesystem check last? 3) How long will it take for TSM to mount a few hundred file volumes during startup? If you decide to use a file device class, limit the size of your volumes and pre-define them. The smaller the volumes are, the less volume contention you will encounter during multiple (multi-session) restores. You should pre-define them to prevent fragmentation on the disks. Kindest regards, Eric van Loon KLM Royal Dutch Airlines -----Original Message----- From: Thorneycroft, Doug [mailto:[EMAIL PROTECTED] Sent: Friday, June 17, 2005 19:47 To: ADSM-L@VM.MARIST.EDU Subject: File dev. type vs. VTL I'm getting ready to add more disk to my TSM server, Are there any advatage/disadvatages to using a Virtual tape library instead of TSM defined file device types. (Do TSM file device types work with multi session restores?) Doug Thorneycroft > Systems Analyst > County Sanitation Districts of Los Angeles County > 1955 Workman Mill Road > Whittier, CA 90601 > Tel: (562)699-7411, Ext. 1058 > Fax:(562)695-6756 > www.lacsd.org > > ********************************************************************** For information, services and offers, please visit our web site: http://www.klm.com. This e-mail and any attachment may contain confidential and privileged material intended for the addressee only. If you are not the addressee, you are notified that no part of the e-mail or any attachment may be disclosed, copied or distributed, and that any other action related to this e-mail or attachment is strictly prohibited, and may be unlawful. If you have received this e-mail by error, please notify the sender immediately by return e-mail, and delete this message. Koninklijke Luchtvaart Maatschappij NV (KLM), its subsidiaries and/or its employees shall not be liable for the incorrect or incomplete transmission of this e-mail or any attachments, nor responsible for any delay in receipt. ********************************************************************** ----------------------------------------- The information contained in this message is intended only for the personal and confidential use of the recipient(s) named above. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this document in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify us immediately, and delete the original message.
