tuck@iris.ucdavis.edu (Devon Tuck) (08/10/90)
In article <4@icdi50.UUCP> Steve writes: > >Does anybody know of a utility that will back up an entire disk drive to >streaming tape under SCO Xenix or Unix. > >The utility that I would like to have would allow the end user to backup >every block of the disk thereby allowing a complete disk restore from the >tape. This would therefore include the operating system and all filesystems. Steve, I just went through GREAT pain to do this successfully. I see a few different possibilities here. SEVERAL ALTERNATIVES FOR BACKING UP AN ENTIRE FILE SYSTEM ========================================================= DISCLAIMER: The following guidelines for backing up a filesystem have come from trial and error, several other sources (see REFERENCES), and much deliberation about the pluses and minuses of the following alternatives. It is my intention that this article save many of you the trouble and lost time, files that I experienced on my way to enlightenment. Since this is a rather complex process, and there are many options to consider, and every system is unique, I hope that others will step in to correct, or add to what I have submitted. -- Devon Tuck I) If you want to backup the image of your drive, or partitions of it, and A) If your backup device has a friendly DOS oriented program with it that you can boot from floppy, and B) You don't ever intend to move your filesystem to a different type of hard drive (without first doing some other type of backup) Then, you might just want to boot up your dos program and grab the whole drive image. Some of the advantages are, 1) You can restore it without the complexity of... booting a floppy unix filesystem, making sure the target hard drive has it's boot image, it's file system is configured properly, restoring to it, cleaning it, etc. 2) I feel it is more reliable, and much faster than backup, restore. II) If you want a backup of the entire file system, and A) You will not want to retrieve more than one or two specific files from the backup. B) You have either the backup, or dump commands available, and an installed tape driver. C) If you intend to restore ONLY to: 1) An identically partitioned disk, or 2) One that you have done an initial xenix installation on, or 3) One that you have done a divvy / mkfs on and which has a file system partition that is the SAME SIZE OR LARGER. D) You have made a "Bootable, root floppy" with "mkdev fd" after your tape driver was installed in the kernel, then mounted that floppy and copied all useful commands such as (restore, restor, more, ls, mount?, umount, mkfs, any necessary tape programs) onto the drive so that you can boot from this floppy to divvy your disk and restore your filesystem. (NEVER TRY TO RESTORE TO THE SAME FILESYSTEM FROM WHICH YOU BOOTED) and (Always do an "fsck -s /dev/hd0root" after this restore) E) You don't mind that backup is a little ssllooww with some of the older, less dense tape formats (It took 1.25 hours to restore a 110 meg drive using Maynard 60 meg QIC-02 tapes.) Then to backup the /dev/rroot partition you can use "backup -fu0k /dev/(name of tape driver) (size of tape in k)" To verify that there were no tape errors you can do: "restore Cf /dev/(name of tape driver) /dev/rroot" To restore use "restore rf /dev/(name of tape driver) /dev/hd0root", but do it from another file system (such as a boot/root floppy, and only to a file system that is the same size or larger. IMPORTANT: It is a good idea (in other words I didn't do this so it caused me great inconvenience) to do a "/etc/divvy -b 1 -c 1" on your disk, and do a "restore tf /dev/(name of tape driver) /dev/rroot" and redirect this information into a file and print it, or write it down and leave it with the tape. It is important that you know, when you pick the tape up later, the period that the backup covers, the size of the filesystem partitions from which it came, perhaps the files on the tape (you can get this with the T option) and any other pertinent info. III) If you want to backgp the files of an entire filesystem (or a subset), and A) You want faster performance, B) You would like to perhaps retrieve subdirectories, or sets of files, C) You want to restore the information to any unix system running a compliant cpio and unix version, (yes I am being vague, the point is the backup will be much more portable) D) You can do this as root. Then, you can do: "cd /" "find . -depth -print | cpio -ocvm > /dev/(name of tape driver)" to restore, you may be able to do "cpio -icdv < /dev/(name of tape driver)" from your active partition, but it is always safer to boot another file system (such a s a bootable root floppy, mount the filesystem, cd into the mount directory, and do the cpio command. IV) The dd command is also useful for doing filesystem backups, although I have no concept of how portable it is, or what you can get away with on a restore. For example, "dd if=/ of=/dev/(tape device) bs=(block size)" V) I feel inclined to mention that tar will often (always?) not copy device special files, or empty directories, can only handle 17 levels of subdirectories, is very intolerant of tape errors, some versions do not split across multiple volumes unless you give the k and b options. It is usually best to use tar on user files, rather than system files, and certainly not an entire file system. It can be hard to get subdirectories off of a tar backup correctly, so cpio is much more versatille. With it's faults, tar still is probably the most popular format for source code distribution. NOTE: With all of these commands, it is VERY IMPORTANT that you read all of the information supplied by your tape manufacturer, and if you are using one of the above commands, read carefully through ALL the options to make sure you understand what you are doing, and that there is nothing you are leaving out. REFERENCES: The SCO XENIX 2.3 CRASH RECOVERY KIT, A six page fax I received. Numerous SCO Engineers, primarily Paul Hurford. Greg Swallow from Maynard Electronics. The SCO Xenix System V (2.3) Operating System User's Reference, and the SCO Xenix System V (2.3) Runtime environment, for cpio, restore, divvy, mkfs, mount, fsck, backup, etc. SUBMITTED BY: Devon Tuck tuck@iris.ucdavis.edu US Army Corps of Engineers, Hydrologic Engineering Center 609 2nd Street, Ste. D Davis, CA. 95616 (916) 756-1104
alan@mq.UUCP (Alan H. Mintz) (08/11/90)
In article <7558@ucdavis.ucdavis.edu>, tuck@iris.ucdavis.edu (Devon Tuck) writes: > In article <4@icdi50.UUCP> Steve writes: > > > >Does anybody know of a utility that will back up an entire disk drive to > >streaming tape under SCO Xenix or Unix... > > > > II) If you want a backup of the entire file system, and... > D) You have made a "Bootable, root floppy" with "mkdev fd" after > your tape driver was installed in the kernel, then mounted that > floppy and copied all useful commands such as (restore, restor, > more, ls, mount?, umount, mkfs, any necessary tape programs) onto the > drive so that you can boot from this floppy to divvy your disk and > restore your filesystem. (NEVER TRY TO RESTORE TO THE SAME FILESYSTEM ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > FROM WHICH YOU BOOTED) and (Always do an "fsck -s /dev/hd0root" after ^^^^^^^^^^^^^^^^^^^^^ > this restore) While this is the true "party line" as told by SCO, it is possible (not necessarily reliable) to restore an active root filesystem with SOME tape drivers on SOME tape drives on SOME versions of XENIX. If you are stuck in a position of having to do this, do the following: 1) Create a rudimentary bootable filesystem on the hard disk. Install enough of the O/S to be able to link the tape driver into the kernel. 2) Do the restore ("restor fr /dev/erct0 /dev/rroot" or the like...). 3) THIS IS THE IMPORTANT PART. Wait for the tape rewind at the end of the restore (this generally requires that you have an "ear" for the particular drive sounds). While the tape is rewinding, TURN OFF THE POWER. Believe it or not, this results in a completely clean filesystem. It seems that the drivers under which this method works do not allow a sync() to take place until they are done restoring and they are not considered done until the tape has rewound. Note that I present this simply as a matter of interest and a last resort. I would not want to rely on this. It was, unfortunately, required to be done this way on a system that had a certain (stupid) driver that did not seem to want to run from a floppy filesystem. The (VERY popular) manufacturer of said drive could not offer any suggestion and admitted that they had never tried running it from a floppy filesystem ! -- < Alan H. Mintz | Voice +1 714 980 1034 > < Micro-Quick Systems, Inc. | FAX +1 714 944 3995 > < 10384 Hillside Road | uunet: mq!alan > < Alta Loma, CA 91701 USA | Internet: [pending] >