Similar experience here. It SOUNDS like a good idea. But I actually sat down and took a look at the problem a couple years ago in response to an inquiry from management.
Our PC hard drives are getting bigger and bigger - not uncommon to have 40-80 GB hard drives now. As such, the percentage of the drive taken up by things like Windows executables is going down, down, down. I took some sample PC's that I thought were "typical", and looked at what we would save if we could avoid backing up the Windoze executables, and it turned out to be maybe 300-600MB per desktop, maybe 5% of the hard drive, BEFORE compression. (And most of that isn't backed up daily, except as part of the dreaded Win2K System Object, which is another problem.) Anyway, throw in compression, GB ethernet, subfile backup capability, large-capacity tape, etc. I decided that the issue of duplicate files in the backup store wasn't really very important in the grand scheme of things. My opinion and nobody else's, Wanda -----Original Message----- From: ADSM: Dist Stor Manager [mailto:[EMAIL PROTECTED] On Behalf Of Loon, E.J. van - SPLXM Sent: Tuesday, September 14, 2004 3:55 AM To: [EMAIL PROTECTED] Subject: Re: Wishlist Item Hi Jack! Before we started using ADSM we ran a backup application called ESM on our MVS mainframe. It was one of the most sophisticated backup applications at that time (1993). It was created by a company called Legent and later on Legent was bought by Computer Associates. They relabeled it to CA-ESM and now (but I don't know this for sure) it's called BrightStor. This product did what you mentioned. It stored all files just once, so the winfile.exe file was only stored once for all Windows clients. The problem with this approach was that the actual scan process involves some kind of CRC check. Just checking the attributes and file size is not enough to determine whether a file has changed. This scan took far to much time. Also, since some files are identical during backup to version backed up earlier on, your storage pool gets heavily fragmented and thus, a restore took a very long time to complete. Also, storage is getting cheaper and cheaper, so why bother? Kindest regards, Eric van Loon KLM Royal Dutch Airlines -----Original Message----- From: Coats, Jack [mailto:[EMAIL PROTECTED] Sent: Monday, September 13, 2004 22:25 To: [EMAIL PROTECTED] Subject: Wishlist Item Yes, I know I am dreaming, but... An open source program, pcbackup or backuppc something like that on Sourceforge has a very nice feature. If a file is already backed up, it only keeps one copy of that file for ALL its clients! What technique does it use to figure out if the files are identical without comparing them? I didn't research it that far, but I assume it uses something like file size and a checksum of some kind. Anyway, if you have significantly identical client computer you are backing up, just keeping one rather than N copies is better than any compression known to man! It would be another field or so in the database for every file, but it might be worth it! At least as an option. ... Jack ********************************************************************** 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. **********************************************************************
