Back Up commands

[Sundar_7]

Hi,

Sorry..again I am here with some simple

question...

But I am not clear ....

I am very very confused with the back up

commands of HP.

Can any one tell me

* What is the major difference between tar

and cpio..

* I learned fbackup cannot append to the

existing backup..is it??

* What are all the commands that can span

the tapes and what are all the commands that

cannot span the tapes..

* If some files are open while backing up,

will they be backed up...What are all the

commands that are capable of backing up

the open files ???

* What are the all major limitations of

the backup commands in HP

I have seen HP's documentation table listing

the differences.. But still I am not clear...

Anybody who has real time experience may help

me out...

Please try to be little bit elaborate..

(Sure U will get 10 :-))

Thank U in advance

Sundar

[Richard Darling]

Difference between tar and cpio:

major advantage of tar is that it universally used on all UNIX systems. It is also simple to use. A major disadvantage of tar is that you can't backup files > 2 GBytes. One other disadvantage with tar is that is slow.

The only time I used cpio was to copy directories fro mmy old g40 to the new L1000. I was able to copy that directories, and not have to go in and change ownerships. I think that is the major advantgae to cpio.

You are right with fbackup - you can't append - that is inherent in the design of the product, and there isn't anything you can do about it.

I know that with fbackup an open file is retried to back it up five times, and then it is not backed up.

I am not sure what else you were asking - did you want the exact syntax of the commands., also?
RD

[Sundar_7]

Hi Richard,

Thankx for spending time..

But U did nt answer my all questions..

* Is it like tar cannot span the tapes..

will dd,cpio,fbackup,dump can span the tapes

* what about the tar,cpio,dd,dump commands

while backing up active files

I dont need the exact syntax..but only thr

limitations of every backup command in HP.

Thank U

Sundar

[Rick Garland]

Another backup command you might want to look at is the 'dump' or 'vxdump' command. These backup utilities can be appended to previous backups on tapes if you use the proper device, typically the no-rewind device. Many other UNIX flavors have the dump commands as part of the standard utilities. The dump commands keep the permissions, ownerships, and access times. You can write a dump script that will change tapes for you (if you have an autochanger) and the output from the command will tell you if the backup was successful or not.

[Carlos Fernandez Riera]

Hi:

Tar and cpio share same limitations
files > 2GB
uids > 60000

Tar is easier to use than cpio for beginers ( i think).
Both commands ( and file formats) are recognized by all UNIX.

Other utilitys might be not recognized by other UNIX.

Some implementation of tar in any UNIX system span tapes, but if i recall well not in HP-UX.

Tar and cpio will record your open files.

Well , i know all these will not help you very much; try every command and take your own feeling... ;-)

[Rodney Hills]

As far as spanning tapes, I believe fbackup and dump can, and tar and cpio can't.

Two major benefits in using fbackup are that
1) ACL information is saved/restored (tar, cpio, dump can't deal with them).
2) An index is built on the front of the tape that frecover can use to do a fast search when restoring files.

[Bruce Regittko_1]

Hi,

Both tar and cpio will prompt the user for a device file when they reach the end of the tape. Typically, you will put in a fresh tape and then enter the device file of the tape drive and continue.

I have tested this with tar and am trusting the cpio(1) man page for cpio since I am too impatient to wait for cpio to finish. (I'll add a followup if the test fails.)

--Bruce

[Bill Hassell]

If you have a small system (just a few gigabytes of data) then classic Unix programs like tar, pax, cpio, dump are probably OK.

However, these are designed for knowlegeable users. They are not reliable in that they cannot handle errors on tape when reading the data back (they just abort the restore). And restarting in the middle (past an error) of a backup seldom works.

It's very important to note: you don't ever want to append backups to the same tape. Every seasoned sysadmin will have a horror story of lost files or wrong versions because there were 5 or 10 (or worse, an unknown number) backups on a single tape with no documentation. A reliable backup program will have these characteristics:

- central index at the beginning of each tape
- index identifies all files and directories on previous tapes by tape number
- index supports high speed searches on restore
- will identify the right tape to use for a specific file or directory
- supports network backups with reliable socket communication
- supports multiple tape drives automatically (switch the next available drive automatically)
- supports parallel data streams into multiple tape drives at the same time
- has error recovery both during backup as well as restore
- supports auto-loading tape libraries for unattended backups
- allows restoring absolute paths on tape to a local directory structure
- supports large file sizes

tar was written to interchange a few kilobytes of data between computers running Khz (not Mhz) processors and tapes were 1/2 reel-to-reel or data cartridges. cpio has a similar heritage...a gigabyte was difficult to imagine. pax has the advantage of understanding tar and cpio, and so on. These are not tools for today's computers.

fbackup comes closest as freeware to handling large datasets, but if you have dozens of gigabytes (and the data is very valuable), don't rely on a free tool...it's sort of like cut-rate insurance. Cheap but often fails when needed. Look at Omniback from HP or other packages like Hiback (from HiComp) or Legato Networker, etc.

[Joseph A Benaiah_1]

It is true that fbackup cannot append to tapes but a combination of fbackup with dd will allow more than one fbackup archive to be written to a tape as follows:

fbackup -i / -f - | dd of=/dev/rmt/0mn bs=32k

You will probably find that HP will not support the above command although, I have used it on a number of occaions.