I don't understand why collocation should use more tapes. Of course it would be probably better to have one tape by client but if you manage to backup for example 50 small clients on 20 tapes, you could use collocation without buying more tapes. The difference would be that instead of backing up each day all the clients on the last tape, resulting in each client having files on each tape, it will put 2 or 3 clients on each tape. In fact, at the end, you will probabbly have something like each client having files on 2 or three tapes. With full+incremental, depending on the regularity of your full backups, you could have a client on far more tapes, tipically 1 full per week + 4 incremental. With full+differential, you would have each client on 2 tapes, but the amount of data backed up would be bigger because a file modified just after the last full backup would be on each subsequent differential tape. And in fact, as long as I know, most software based on full+incremental are unable of collocation and use more tapes than TSM. But in all cases, the most easy way to restore a full disk or a full computer is to attach a single drive to this computer and make a full backup of this computer each day. Most of my clients make that and in case of a disk failure, everything is simple : you mount the last backup and restore it completely. But if you need a single file .... and if you have 20 computers to backup ....
Etienne GUILLAUMONT e-mail : [EMAIL PROTECTED] RGB Technologie Parc d'Innovation, Bâtiment PYTHAGORE 11 Rue Jean SAPIDUS 67400 ILLKIRCH Tél : 03 90 40 60 60 Fax : 03 90 40 60 61 William Rosette <[EMAIL PROTECTED] To: [EMAIL PROTECTED] JOHNS.COM> cc: Sent by: "ADSM: Subject: Re: progressive backup vs. full + incremental Dist Stor Manager" <[EMAIL PROTECTED] EDU> 05/03/2003 16:21 Please respond to "ADSM: Dist Stor Manager" This progressive incremental confuses me. This is what I thought was going on: 1. Differential is all changes from last FULL backup. 2. Incremental is all changes from last ANY backup 3. Full is all files not matter change on backup. We used to do Differential with Weekend Fulls. During a restore we would restore Full if file had not changed, and then the last differential for the other files that changed. We never restored more than necessary. It depended on the restore. Restore 1 file was the same on Differential as Incremental (most current or before corruption). The problem comes when you are restoring directories or a whole system as in DR. In the Differential Weekend Full world you would restore Full and lay on top the last Differential and your done. Always 2 restores was all and restores flew since data was all together. Now the TSM world has its own database with its own reclamation, expiration, migration, collocation, and the works. Come restoring 1 file it is the same as above. Come restoring directories or whole systems it will depend where all the data is. Our case, if the restore is not far back we have a quick restore, but the further back we go in date the slower the restore because of the no-collocation and the data is spread over 100's of tapes. This seems to be the same as an Incremental that the TSM database keeps track of every file from every tape. Thus, the reason we did not use Incrementals before was 1. Restores were long, 2. No database to keep track of all Incremental tapes, 3. Differential & Full used less tapes, and 4. money. I am still dealing with the progressive incremental that progressively eats resources/money. My suggestion would be for reclamations to reclaim to a collocate status or somehow keeping the data together as it gets older. Right now I am probably going to run FULLs just to keep my restores to a minimum since the tape issue will hurt us if we collocate If I am off, I would appreciate anyone that can straighten out my backups/restores. Thank You, Bill Rosette Data Center/IS/Papa Johns International WWJD Gianluca Mariani1 <gianluca_mariani@ To: [EMAIL PROTECTED] IT.IBM.COM> cc: Sent by: "ADSM: Subject: Re: progressive backup vs. full + incremental Dist Stor Manager" <[EMAIL PROTECTED] EDU> 03/05/2003 09:47 AM Please respond to "ADSM: Dist Stor Manager" Progressive incremental backs up only new or changed files. during the initial backup the client backs up all eligible files of course(full backup). Subsequently, files are backed up again only if they are new or have changed since the last backup. In TSMs case, a pointer to each version of every file for every client is kept in the database , so there is no need for another full backup. When you need to restore, you can choose the specific version of the file or point-in-time to restore, and TSM will restore only that particular file or files. The approach used for full + incremental backups (NetBackup) requires an initial full backup, followed by regular incremental or differential backups (usually once a day), with the complete cycle needing a full backup to be repeated on a regular (usually weekly) basis. This backup method results in redundant weekly full backups of files that have not changed, wasting both network and media resources. The multi-step restore process in this approach requires the software to restore the last full backup, then to restore incremental or differential backups on top of that in order to recover the latest version of a file or an entire system. This methodology not only involves restoring more data, it also means more tape mounts and tape positioning and consumes more network bandwidth all of which amounts to having longer restore times. Cordiali saluti Gianluca Mariani Tivoli TSM Global Response Team, Roma Via Sciangai 53, Roma phones : +39(0)659664598 +393351270554 (mobile) [EMAIL PROTECTED] ---------------------------------------------------------------------------------------------------- The Hitch Hiker's Guide to the Galaxy says of the Sirius Cybernetics Corporation product that "it is very easy to be blinded to the essential uselessness of them by the sense of achievement you get from getting them to work at all. In other words ? and this is the rock solid principle on which the whole of the Corporation's Galaxy-wide success is founded -their fundamental design flaws are completely hidden by their superficial design flaws"... Joni Moyer <[EMAIL PROTECTED] HMARK.COM> To Sent by: "ADSM: [EMAIL PROTECTED] Dist Stor cc Manager" <[EMAIL PROTECTED] bcc ST.EDU> Subject progressive backup vs. full + 05/03/2003 incremental 15.21 Please respond to "ADSM: Dist Stor Manager" Hello everyone! I was wondering why the full + incremental would result in a longer restore time than the progressive backup methodology? From several co-workers point of view they thought that it would be quicker on the full + incremental because you wouldn't have to go back to the beginning backups of the file and restore all of the incrementals, you would just go back to the most recent full backup and apply the incrementals after that point. When I went to explain the reasoning behind this, I had some problems understanding the concept myself, so I was hoping someone could explain both methods and why they differ in restore time and why progressive is better than the full + incremental. Thank you so much for any help you can lend on this matter! Joni Moyer Systems Programmer [EMAIL PROTECTED] (717)975-8338