I have a question that's not nessasarily a linux question. I have just now
gone through an ordeal where my computer froze, I had to hit reset and
there was a problem with one of my partitions. I finally got it fixed and
am able to mount it, but the directory structure is destroyed and I've had
to rebuild it.

First, will errors occur on a hard drive if it's not mounted?
Secondly, what's the best method to back up a partition, the whole thing
(greater than 100GB) in linux? Tar the whole thing? Just make an image
file with dd? What do you guys do?
--
lucas
-------------------------
Perl Coder since 2001
shift || die;
-------------------------

lucas wrote:

> I have a question that's not nessasarily a linux question. I have just
> now gone through an ordeal where my computer froze, I had to hit reset and
> there was a problem with one of my partitions. I finally got it fixed and
> am able to mount it, but the directory structure is destroyed and I've had
> to rebuild it.

> First, will errors occur on a hard drive if it's not mounted?

If the drive itself is malfunctioning, Yes!

> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?

I would have to recommend backing up important directories like /home /root
and /var/spool at a minimum.

Now that the filesystem is damaged, I am not sure what you intend to do,
especially if it has been used for a number of years. If you are looking
for a forensic recovery, that can be extremely expensive.

Further, even reading a damaged filesystem can cause even more problems.

So, give us more information:

(1) How old is the filesystem installation.
(2) What filesystem are you using?
(3) How full was it?
(4) What kind of use did you make of it?
(Lots of small files with lots of deletions)

That should do for a start.

Bar

That should be a good start.

On Sun, 05 Nov 2006 01:36:11 -0500
lucas <na@noaddress.com> wrote:
> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?

I am not sure but perhaps some of these can help:

http://foremost.sourceforge.net/
http://servers.linux.com/servers/06/...tid=119&tid=13
http://en.wikipedia.org/wiki/Data_recovery

-- Mikhail

lucas <na@noaddress.com> wrote:
> First, will errors occur on a hard drive if it's not mounted?

If you have some kind of odd error that causes writes to the
parts of the disk containing you unmounted partition it could break the
partition even though it is unmounted.

> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?

I prefer tar with compression. And mostly for speed reasons I prefer gzip
over bzip2 when doing big backups even though the backup files get a
little bigger.

An image made with dd would only be useful if you restore the entire
partition to another partition which has and identical geometry. You will
also be limited to use the same file system.

With tar you also have the advantage that you can restore single files or
directories from you backup.

I almost never have to restore a backup because a disk has crashed. Mostly
it is because someone has accidently removed or overwritten files.

There are many programs for doing backups. There are both commersial and
free programs. However, I still prefer tar as it has the advantage of
being a standard program and I probably will have access to it even if I
boot from something odd like a rescue floppy. Tar also works the same on
different operating systems. If I would use a program like Solaris dump I
would only be able to restore with Solaris.

regards Henrik
--
The address in the header is only to prevent spam. My real address is:
hc8(at)uthyres.com Examples of addresses which go to spammers:
root@variousus.net root@localhost

On 2006-11-05, lucas <na@noaddress.com> wrote:
> I have a question that's not nessasarily a linux question. I have just now
> gone through an ordeal where my computer froze, I had to hit reset and
> there was a problem with one of my partitions. I finally got it fixed and
> am able to mount it, but the directory structure is destroyed and I've had
> to rebuild it.
>
> First, will errors occur on a hard drive if it's not mounted?
> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?

I would most surely not ever trust that drive again... but there are
ways to recover the data on the drive. Most of the time there will be
sector errors on the drive. These can be repaired with tools. The one
we (a school in the netherlands) use is HDD Regenerator by Dimitri
Primochenco (http://www.dposoft.net), it takes an awfull long time
and is not a free tool.... but for us it has been worth the time and
money.

As for backing up the data.... I would make tar.gz files of important
data ASAP. My defininition of important may differ from yours, but I
would do: /etc /home and /var

Hope this helps.... have fun...

Peter
--
"A radioactive cat has eighteen half-lives."

On Sun, 05 Nov 2006 01:36:11 -0500, lucas wrote:

> I have a question that's not nessasarily a linux question. I have just now
> gone through an ordeal where my computer froze, I had to hit reset and
> there was a problem with one of my partitions. I finally got it fixed and
> am able to mount it, but the directory structure is destroyed and I've had
> to rebuild it.
>
> First, will errors occur on a hard drive if it's not mounted?
> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?
>
I agree there could be a problem with your disk, but it could also be
something else- such as, a bad memory stick. Do some validation and
checking using smartctl for the disk, and memtest for your memory.

Software Tools...
As for general tools for backing up, I use tar with gzip (as another
poster recommended.) If I want to make sure the backup image is
completely consistent, I make the backup from a rescue disk/image. That
way the system will not be changing as it is backed up. My rescue disk
needs networking to save the backup to its target (below).

There are other options for the backup image, too (beside dd and tar).
Virtual computers offer some interesting backup options, for example.

Hardware/Network Environment...
I use external USB 2.0 HDs for the backup target device. These a good
choice for backing up because they have adequate capacity and can be
turned off and put away while not in use. However, any separate disk
is better than nothing. Also, IMO, it is better if the backup
device is connected to a separate computer- perhaps, backing up to a
dedicated backup server which has adequate storage capacity, etc.

Semi OT....
The new Linux kernel features (device mapper) make using
encryption very easy. Backups can be written to an encrypted volume and
reduce risks from lost data sets. Also, there is a noticable CPU hit when
using both gzip and device mapper encryption. A dual CPU system is better
at performing this job. I could post some simple statistics, but the time
spent compressing files will vary with how compressible the input
data is, and vary with the CPU power of the machine performing the job.

--
Douglas Mayne

On Sun, 05 Nov 2006 01:36:11 -0500, lucas wrote:

> I have a question that's not nessasarily a linux question. I have just now
> gone through an ordeal where my computer froze, I had to hit reset and
> there was a problem with one of my partitions. I finally got it fixed and
> am able to mount it, but the directory structure is destroyed and I've had
> to rebuild it.
>
> First, will errors occur on a hard drive if it's not mounted?
> Secondly, what's the best method to back up a partition, the whole thing
> (greater than 100GB) in linux? Tar the whole thing? Just make an image
> file with dd? What do you guys do?

My two cents, after having had to rescue myself from a couple of
'disasters' this year - one totally hardware, one self inflicted.

This points out to me the logic of having a number of smaller partitions -
10-20gb are manageable. I've used dd with conv=noerrors conv=sync to
recover a partition to a file on another drive. Then loop mount and
recover the data. There is also a utility that will help recover the
partition table if it's destroyed. Any time you suspect a problem - DON'T
MOUNT THE PARTITION. Immediately do a badblocks check to see if there is a
physical problem - hard drives are really cheap now (in both senses of the
word?). It's easy and inexpensive to install a new, larger disk and copy
the partitions of interest there. A Live CD or a quick basic install on
the new disk might be in order - if you use a USB external drive it's
going to take a while.

BTW - when I had the bad drive problem, I was able to recover the two
partitions in which I was interested, and to date I have found one
partially corrupted file - everything else was fine, in spite of a
corruption of the partition table when it died - just go slow, take your
time, don't panic.

Bar wrote:

>> First, will errors occur on a hard drive if it's not mounted?
>
> If the drive itself is malfunctioning, Yes!
>
>> Secondly, what's the best method to back up a partition, the whole thing
>> (greater than 100GB) in linux? Tar the whole thing? Just make an image
>> file with dd? What do you guys do?
>
> I would have to recommend backing up important directories like /home
> /root and /var/spool at a minimum.
>
> Now that the filesystem is damaged, I am not sure what you intend to do,
> especially if it has been used for a number of years. If you are looking
> for a forensic recovery, that can be extremely expensive.
>
> Further, even reading a damaged filesystem can cause even more problems.
>
> So, give us more information:
>
> (1) How old is the filesystem installation.
> (2) What filesystem are you using?
> (3) How full was it?
> (4) What kind of use did you make of it?
> (Lots of small files with lots of deletions)


1. The filesystem is probably about 1 years old
2. ext2
3. 75GB/90GB
4. It was a storage drive. Not many writes or deletes. A lot of small
files, pictures, some music, compressed files.

I have most if not all my files back now. I've started rebuilding the
directory structure. It is the second partition on a two partition drive.
The first partition is fine, oddly.

--
lucas
-------------------------
Perl Coder since 2001
shift || die;
-------------------------

ray wrote:

> This points out to me the logic of having a number of smaller partitions -
> 10-20gb are manageable.

I think you may be right about the smaller partitions. I never had a
problem with my smaller drives. Only these 3 big ones.

--
lucas
-------------------------
Perl Coder since 2001
shift || die;
-------------------------

Douglas Mayne wrote:

> Semi OT....
> The new Linux kernel features (device mapper) make using
> encryption very easy. Backups can be written to an encrypted volume and
> reduce risks from lost data sets. Also, there is a noticable CPU hit when
> using both gzip and device mapper encryption. A dual CPU system is better
> at performing this job. I could post some simple statistics, but the time
> spent compressing files will vary with how compressible the input
> data is, and vary with the CPU power of the machine performing the job.

I've tried disk encryption on linux, and found it's difficult to do with
2.4.x kernel. Do you know of one that would work with that version? I'm
using Slackware 10.1 Kernel 2.4.29.
--
lucas
-------------------------
Perl Coder since 2001
shift || die;
-------------------------