nelson@sun.soe.clarkson.edu (Russ Nelson) (12/13/90)
I've got two filesystems to back up, and only one tape drive, and I'd like to do unattended backups. Can I really only back up one filesystem per tape? Well, of course I mean, will I be able to *restore* from a tape with two backups on it? -- --russ (nelson@clutx [.bitnet | .clarkson.edu]) FAX 315-268-7600 It's better to get mugged than to live a life of fear -- Freeman Dyson I joined the League for Programming Freedom, and I hope you'll join too.
ronald@robobar.co.uk (Ronald S H Khoo) (12/14/90)
nelson@clutx.clarkson.edu (aka NELSON@CLUTX.BITNET) writes: > I've got two filesystems to back up, and only one tape drive, and I'd > like to do unattended backups. Can I really only back up one > filesystem per tape? Well, of course I mean, will I be able to *restore* > from a tape with two backups on it? Depends on what kind of tape drive you have. If it's an Irwin drive or something like that which does not support a non-rewinding device, then NO. If it's a QIC-02/QIC-24 thingy sure, why not? Judicious use of the non-rewinding device (/dev/nrct0) and the "tape rfm" command will get you most places. Of course if there's an error *anywhere* on the tape, you can't skip past it, so if the first archive is busted, you can't get at the second, but that's a generic problem with cartridge tapes in general. BTW, if you're serious about doing unattended backups like that, I recommend getting the UFM (a.k.a. xnx155b) update from SCO because there's a much better cpio there -- the Xenix dumprestor isn't really much good, so I recommend cpio. Also, there's a better cartridge tape driver in UFM. What I don't understand about unattended backups is, how do you get all the users processes off the filesystem ? Or do you risk backing up a live filesystem? In that case *definitely* don't use the Xenix dumprestor -- it gets very confused real easily in a completely unrecoverable way from inconsistent backups (and from consistent ones as well, I think) -- ronald@robobar.co.uk +44 81 991 1142 (O) +44 71 229 7741 (H)
chip@chinacat.Unicom.COM (Chip Rosenthal) (12/14/90)
In article <NELSON.90Dec12212501@image.clarkson.edu> nelson@clutx.clarkson.edu (aka NELSON@CLUTX.BITNET) writes: >I've got two filesystems to back up, and only one tape drive, and I'd >like to do unattended backups. Can I really only back up one >filesystem per tape? Well, of course I mean, will I be able to *restore* >from a tape with two backups on it? Use the /dev/nrct0 (no rewind device) instead of /dev/rct0 for the backups. It doesn't make doing the backups that much more difficult. However, doing the restore is a royal pain in the butt. For example, if you are using "dump" to make the backups upon /dev/nrct0, what you need to do for a restore is: 1) Do enough "tape rfm" commands to get to the dump archive you need. 2) Run the restore command. Wait for it to find the files and prompt you to insert the backup volume. 3) Jump over to another multiscreen. 4) Rewind the tape. 5) Run the same number of "tape rfm" commands to get back to the same archive. 6) Pop back to the first multiscreen and tell "restore" to continue on. This is one of the reasons why I use "afio" for XENIX backups. In Unicom System Development's Fall '90 newsletter, I did a brief article on afio, and compared it to dump and cpio for backups. It included some benchmarks as well. If you'd like a copy of the article, send me a snail mail address. Afio is available in comp.sources.unix archives (volume 12). -- Chip Rosenthal 512-482-8260 | We was raising insurance premiums, ma. Unicom Systems Development | We was spreading fear of arson. <chip@chinacat.Unicom.COM> | - Michelle Shocked
paulz@sco.COM (W. Paul Zola) (12/24/90)
In article <NELSON.90Dec12212501@image.clarkson.edu> nelson@clutx.clarkson.edu (aka NELSON@CLUTX.BITNET) writes: }I've got two filesystems to back up, and only one tape drive, and I'd }like to do unattended backups. Can I really only back up one }filesystem per tape? Well, of course I mean, will I be able to *restore* }from a tape with two backups on it? } }-- }--russ (nelson@clutx [.bitnet | .clarkson.edu]) FAX 315-268-7600 }It's better to get mugged than to live a life of fear -- Freeman Dyson }I joined the League for Programming Freedom, and I hope you'll join too. You don't say if you are using an SCO system or not, but from the newsgroup I assume you are. The following article from the SCO Information Tools database should help with your problem. ################## cut here ################ cut here ################## How to store multiple archives or backups onto a single cartridge tape KEYWORDS: no rewind QIC cartridge tape drives multiple archives tar cpio backup /dev/nrct0 xenix RELEASE: SCO XENIX Release 2.2 and later SCO UNIX System V/386 Generic PROBLEM: How can more than one backup, cpio, or tar archive be written to a single tape cartridge? SOLUTION: The no-rewind device allows the SCO XENIX user to write and read QIC tapes without automatically rewinding them, as is the default for other tape devices. Using the no-rewind tape device /dev/nrct0, multiple files or archives can be written to a tape. For example, the following three commands, if given in succession, will write three tar archives to the tape currently in the tape drive: tar cvbf 20 /dev/nrct0 /a tape -c wfm tar cvbf 20 /dev/nrct0 /b tape -c wfm tar cvbf 20 /dev/nrct0 /c Once the desired archives have been written, the tape must be rewound before it may be read. Use the "tape rewind" command to rewind the tape. After multiple items have been written, the "rfm" (read file mark) option to the tape(C) command can be used to seek to the desired item. To retrieve the third tar archive written by the example commands above, use the following command: tape -c rfm; tape -c rfm; tar xv6 The no-rewind device may be used in the same way to read and write multiple cpio(C) archives, or backups from the backup(C) command. NOTE: There is no no-rewind device available for Irwin tape drives, so the above techniques apply to quarter-inch cartridge (QIC) tape drives only. ################## cut here ################ cut here ################## I hope this helps with your problem, and is of general interest as well. - Paul Zola Software Support Engineer paulz@sco.COM We only know in theory what we are doing. - Kate Bush DISCLAIMER: I speak for myself, and not for SCO.