Help! Restore whole from tar?

Help! Restore whole from tar?

Post by Dogbe » Fri, 27 Sep 1996 04:00:00



Hi

I have a sparc2 that will boot single user and I can get tar to work
( I have all of the basics...) but I need to restore the
system from a tar tape archive. (I have the complete system on tape)

My dilema is,  If I extract the files while the system is running, won't
it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
too :)

How is that done, anyway?   I need to do a full system restore on top
of a (basically) working system.

Any sugesstions greatly appreciated!!!

Dan

 
 
 

Help! Restore whole from tar?

Post by Chad T. Burkin » Mon, 30 Sep 1996 04:00:00



> Hi

> I have a sparc2 that will boot single user and I can get tar to work
> ( I have all of the basics...) but I need to restore the
> system from a tar tape archive. (I have the complete system on tape)

> My dilema is,  If I extract the files while the system is running, won't
> it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
> too :)

> How is that done, anyway?   I need to do a full system restore on top
> of a (basically) working system.

> Any sugesstions greatly appreciated!!!

> Dan


Normally, you would boot from a CD-ROM
ex:  boot cdrom -sw

This will get you into single-user without actually using
any of your disks.  Then you can do a full restore from your
tape.  Don't forget to re-install the bootblock for the
disk (I think the correct command is bootblk, do a man on it).

BTW, when you boot from CD-ROM, /dev and /devices are built
in /tmp

-Chad Burkins
-Lockheed Martin

 
 
 

Help! Restore whole from tar?

Post by Gerald Jahr » Sat, 05 Oct 1996 04:00:00


: Hi

: I have a sparc2 that will boot single user and I can get tar to work
: ( I have all of the basics...) but I need to restore the
: system from a tar tape archive. (I have the complete system on tape)

: My dilema is,  If I extract the files while the system is running, won't
: it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
: too :)

: How is that done, anyway?   I need to do a full system restore on top
: of a (basically) working system.

: Any sugesstions greatly appreciated!!!

: Dan

The system should continue to run as normal for the most part. After the recover reboot.

As to the dev files, they should have the same names and minor numbers if it is from this system.

Of course there are no guarantees.......in unix......

 
 
 

Help! Restore whole from tar?

Post by Louis J. LaBash J » Sun, 06 Oct 1996 04:00:00



|
|: Hi
|
|: I have a sparc2 that will boot single user and I can get tar to work
|: ( I have all of the basics...) but I need to restore the
|: system from a tar tape archive. (I have the complete system on tape)
|
|: My dilema is,  If I extract the files while the system is running, won't
|: it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
|: too :)
|
|: How is that done, anyway?   I need to do a full system restore on top
|: of a (basically) working system.
|
|
|: Any sugesstions greatly appreciated!!!
|
|: Dan

|
|The system should continue to run as normal for the most part. After the
|recover reboot.  As to the dev files, they should have the same names and
|minor numbers if it is from this system.

When I tried to do something similar: got "text files busy", can't create
links, ... .  That scared me, I used a set of disk (boot/install) that
loaded the OS into RAM, mounted my harddisk and restored the tar.  Worked
like a charm.

Hope this is of some utility.
--

 
 
 

Help! Restore whole from tar?

Post by Mark Sitkowsk » Tue, 08 Oct 1996 04:00:00




> : Hi

> : I have a sparc2 that will boot single user and I can get tar to work
> : ( I have all of the basics...) but I need to restore the
> : system from a tar tape archive. (I have the complete system on tape)

> : My dilema is,  If I extract the files while the system is running, won't
> : it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
> : too :)

> : How is that done, anyway?   I need to do a full system restore on top
> : of a (basically) working system.

> : Any sugesstions greatly appreciated!!!

> : Dan

> The system should continue to run as normal for the most part. After the recover reboot.

> As to the dev files, they should have the same names and minor numbers if it is from this system.

> Of course there are no guarantees.......in unix......

One thing you can guarantee, is that tar would have refused to put
any /dev files onto the tape in the first place. They're not files at
all, in the strict sense of the word. So, that won't cause you any pain.
However, restoring /vmunix, when it's running, might. My suggestion
would be to boot off a CD, mount the miniroot in /dev/swap, and then
restore from tape. If you don't have a CD, mount a second system disk,
boot off that, then restore the original.

--
Best regards,
Mark

 --------------------------------------------------------------------------
 Mark Sitkowski                             !
 "In God we trust.  All others pay cash..."
 5 Bronaldi Street
 Heathmont Victoria 3135
 --------------------------------------------------------------------------
 Home phone: (613-9) 729-0731                !

 --------------------------------------------------------------------------

 
 
 

Help! Restore whole from tar?

Post by Matthew Tove » Thu, 10 Oct 1996 04:00:00




> : Hi

> : I have a sparc2 that will boot single user and I can get tar to work
> : ( I have all of the basics...) but I need to restore the
> : system from a tar tape archive. (I have the complete system on tape)

> : My dilema is,  If I extract the files while the system is running, won't
> : it crash? (ya know, if I overwrite /dev with a new /dev, etc... (that
> : too :)

> : How is that done, anyway?   I need to do a full system restore on top
> : of a (basically) working system.

> : Any sugesstions greatly appreciated!!!
> The system should continue to run as normal for the most part. After the recover reboot.

> As to the dev files, they should have the same names and minor numbers if it is from this system.

> Of course there are no guarantees.......in unix......

This sort of operation is SUPPOSED to work, but it wouldn't be good for
my nerves!
A less stressful method would be to boot on an external disk or off CD
and then restore onto the system disk...

Matt
--
Matt Tovey                              http://wwwcn.cern.ch/~mtovey

Linux is okay, but the boxes it comes in are too small.

 
 
 

1. tar vs. dump/restore, why does everybody seem to use tar?

I've been seeing posters in comp.os.linux.hardware almost exclusively
referring to 'tar' as the way they are doing system backups to tape.

Though I'm fairly new to Linux I've done UNIX sysadmin for years
and have always used 'dump' instead of 'tar'.  I suppose that some of
the reasons I don't use tar are probably historical -- old tar
implementations barfed on really long filenames as well as not knowing
about filesystem boundaries.  Even with the newfangled GNU tar
features, I still see that dump/restore may have a couple advantages
over tar:

  dump uses a master/slave arrangement when writing tapes which (I
  believe) helps to keep the tape buffers full which leads to better
  streaming behavior and thus possibly better performance on the tape
  drive.

  dump seems to be somewhat faster if the output device isn't the
  major limiting factor, such as when using tar or dump to move files
  from one partition to another.  In some brief tests on a (P166,
  2.0.10, AHA2940U) alternately dumping and taring a 200M filesystem
  onto a disk file (on a separate scsi drive) using the '-f' flag I
  found that tar was consistently slower on the order of 20-30%.  I
  don't have a tape drive handy right now to do testing, but I suspect
  that some of these factors could lead to improved performance on
  tape too.

  dump writes a file table at the beginning of the dump which allows
  you to look at the archive contents without having to read the whole
  file.  The 'restore' command also has an interactive mode which
  allows for fast, easy and selective restoral of files.

  dump also has rudimentary concept of incremental backups and
  optionally keeps track of backup dates its own simple database.

As I said above I'm fairly new to Linux so there may be aspects of tar
and dump under Linux which I don't grasp, but it seems to me that
folks should check out the features of dump to see if they don't
better meet their backup needs.

One caveat though, I needed to recompile dump to get it to work
consistently under 2.0.x.  There were problems with the communication
between the master and slave during some dumps which would cause the
dump to fail.  Never did figure-out the root cause, but recompiling
has seemingly fixed it.

David

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