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Windows Server Forum / Small Business Server / SBS 2000 / August 2004Backing Up
I'm using a VS80 DAT drive with 80Gb tapes Veritas 9 backup exec. Software Compression enabled, hardware compression enabled. Yet it runs out of tape space at just under 56Gb.. Does anyone know why ..?? Is there some sort of file byte size or Block size issue between SBS and backup Software? If I remove some files, so that there is less than 56Gb of data, then it backs up fine and resets exchange logs.. Any help apprecieated.. If you're using 40/80 (uncompressed/compressed) capacity tapes, you won't get the full 80 GB using compressing. Most drives will only give you about 1.6 x (uncompressed capacity) with compression turned on. That's about 64 GB for a 40/80 tape. This can very from 1.5x to about 1.8x. So, this may be the wall you're hitting.  SignatureMerv Porter [SBS MVP] =================================== > I'm using a VS80 DAT drive with 80Gb tapes > [quoted text clipped - 11 lines] > > Any help apprecieated.. Ok... scratch what I said. I just re-read your post and noticed that I hadn't read it in its entirety. SignatureMerv Porter [SBS MVP] =================================== > I'm using a VS80 DAT drive with 80Gb tapes > [quoted text clipped - 11 lines] > > Any help apprecieated.. > Ok... scratch what I said. I just re-read your post and noticed that > I hadn't read it in its entirety. Why? AFAICT, it sounds like your explanation was exactly right. I never count on getting more than about 20% over the native capacity of a tape. Manufacturers claims are always based on at least 2:1 compression, which is only really feasible if what you're backing up is just data, and mostly compressible (ie not much in the way of MP3, JPEG, ZIP, etc files). SignatureSteve Foster [SBS MVP] --------------------------------------- MVPs do not work for Microsoft. Please reply only to the newsgroups. EEcck.. Ok .. right .. didn't know that .. Anyone have any nice links to explain Incremental Backups and what they are and how they work etc.etc. Looks like that is the only way forward now Or delete some mailboxes [evil grin] Npp > > Ok... scratch what I said. I just re-read your post and noticed that > > I hadn't read it in its entirety. [quoted text clipped - 5 lines] > just data, and mostly compressible (ie not much in the way of MP3, > JPEG, ZIP, etc files). > EEcck.. > > Ok .. right .. didn't know that .. > > Anyone have any nice links to explain Incremental Backups and what > they are and how they work etc.etc. Ick. To paraphrase someone else from earlier today - "Incremental Backups are the Source of All Evil". > Looks like that is the only way forward now You could probably afford to be a little selective in what gets included in a "Full" Backup (eg most of C:\Program Files doesn't change much, ClientApps is fairly static, etc) - perhaps with two alternating jobs. > Or delete some mailboxes [evil grin] Exclude *.MP3 from the backup jobs. <g> SignatureSteve Foster [SBS MVP] --------------------------------------- MVPs do not work for Microsoft. Please reply only to the newsgroups. > If I remove some files, so that there is less than 56Gb of data, then it > backs up fine and resets exchange logs.. I think I was second guessing my interpretation of this line further on in post. Hey, as long as Npp has his answer, I'm happy. :-) SignatureMerv Porter [SBS MVP] =================================== > > Ok... scratch what I said. I just re-read your post and noticed that > > I hadn't read it in its entirety. [quoted text clipped - 5 lines] > just data, and mostly compressible (ie not much in the way of MP3, > JPEG, ZIP, etc files). > I think I was second guessing my interpretation of this line further on in > post. Hey, as long as Npp has his answer, I'm happy. :-) Well if what your saying is 80Gb is not actually 80Gb and more likely 56Gb or thereabouts depending on file types, then I'll have to look at another solution.. I'm not happy with the answer - but that's not your fault :-) (I'd of liked - yeah click this click that and install this patch -then you can back up full 80Gb) Thanks for the replies. Npp > > If I remove some files, so that there is less than 56Gb of data, then it > > backs up fine and resets exchange logs.. [quoted text clipped - 11 lines] > > just data, and mostly compressible (ie not much in the way of MP3, > > JPEG, ZIP, etc files). > > I think I was second guessing my interpretation of this line > > further on in post. Hey, as long as Npp has his answer, I'm happy. [quoted text clipped - 5 lines] > your fault :-) (I'd of liked - yeah click this click that and install > this patch -then you can back up full 80Gb) A: Ignore the compressed capacity, and work on the native. If you have 80Gb disk storage capacity, you realistically need an 80/<something> (or better) tape capacity. You _might_ get away with 60/<something>, but 40/80 is not going to cut it. Tape capacity is always quoted as <native>/<compressed> with the compressed figure usually calculated at a 2:1 ratio, although Sony use 2.6:1 for AIT (madness, IMHO). The only thing you can rely on is that 40Gb of files will fit on a 40Gb native tape. It _might_ fit on a 20Gb native tape *if* the data compresses well. Personally, I've never yet witnessed a business where they achieved 2:1 compression of their data. The best I've seen is around 1.2:1. SignatureSteve Foster [SBS MVP] --------------------------------------- MVPs do not work for Microsoft. Please reply only to the newsgroups. |
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