Re: [BackupPC-users] Backup/Restore Windows Registry

[Craig Barratt <craig@ar...>]

> My boss just asked me if Backup PC can backup and restore the registry files
> on Windows PC's (98, NT, Win2K, etc).
> Anyone know the answer?

I think the answer is no.  BackupPC backs up all the files that can
be accessed via an SMB share.  If the registry files are locked or
not readable then they won't be backed up.

I've looked around at some of the log files (output from smbclient)
for win2k clients at our site and I see errors like:

    ERRDOS - ERRbadshare (The sharing mode specified for an Open conflicts with existing  FIDs  on the file.) opening remote file \WINNT\system32\config\SYSTEM (\WINNT\system32\config\)
    ERRDOS - ERRbadshare (The sharing mode specified for an Open conflicts with existing  FIDs  on the file.) opening remote file \WINNT\system32\config\SYSTEM.ALT (\WINNT\system32\config\)

so I suspect that the registry files are locked and therefore not
accessible on an SMB share.

In general a safe method for backing up databases (like the registry
or any RDBMS) is at (or close to) the application level, rather than
the disk files, since the disk files might not represent a consistent
snapshot of the data.  That requires client-side software, which is
not currently part of the BackupPC setup.

A workaround for backing up the registry would be to create a Windows
script of some kind that copies the registry files to a backup directory
periodically (perhaps at startup or login?).  BackupPC should then
successfully backup these copies.

Craig

[BackupPC-users] backup over the Internet

[Lonnie Cumberland <lonnie@ou...>]

Hello All,

I am new to this list and was wondering if some one could tell me if
it is possible to us this software to backup systems that are
elsewhere on the Internet.

I think that I had heard, somewhere, that the NetworkNeighborhood is
only able to talk to other machines that are on the local net and and
I was also worried about the bandwith consumption as well in using
this method.

How would a Windows user from somewhere access out system which is
Linux? I am a big Linux user and not really a Windows users so I am
unclear on this.

Best Regards,
Lonnie

-- 
 Lonnie Cumberland
 OutStep Technologies Incorporated
 (313) 832-7366

 URL: http://www.outstep.com
 EMAIL: Lonnie@...
      : Lonnie_Cumberland@...

[BackupPC-users] Re: Reducing Network Requirements

[<maral@ph...>]

Craig Barratt writes:

> peter> Its good to have a data set to measure against. I certainly
> peter> dont have 200GB of disk lying around spare or 100 laptops.
> peter> I'ld be interested in the same figures using smaller blocks
> peter> and larger blocks.
> peter> i.e. 4k, 8k, 32k, 64k.
>
> craig> I'll have to either write it in C or write some scripts that do
multiple
> craig> passes using temporary files which are merged in a later step.
I'll
> craig> probably pick the latter, but I need to work more on v1.04 first.
>
> peter> use Fcntl;
> peter> use SDBM_File;
> peter> tie(%Count, 'SDBM_File', '/tmp/md5_hash', O_RDWR|O_CREAT|O_TRUNC,
0644);
> peter> $Count{MD5(block)}++;
> peter> untie(%Count);
>
> Nice suggestion!  I tried this out but the sdbm files got pretty large
> (over 2GB) for the small block sizes, and for some reason it got quite
> slow even when less than 10% done.
>
> Anyhow, I implemented a two-step solution: computing all the block
> hashes and different block sizes and writing them to files (almost
> 6GB for the 1k block size case), then doing the counting in multiple
> passes to avoid large memory use.
>
> Here are the results (counting all the blocks and unique blocks for
> different block sizes in a pool that is around 240GB uncompressed):
>
>     Block size     Total Count     Unique Count    Percentage duplicate
>      1024     248015738     151849516      38.8%
>      2048     124446044      78608689      36.8%
>      4096      62693124      41013766      34.6%
>      8192      31868433      21806649      31.6%
>     16384      16500899      11627485      29.5%
>     32768       8853617       6501388      26.6%
>     65536       5073159       3950319      22.1%

Thanks for that.

These are based on comparing against fixed block size boundaries correct?
i.e. for 1024 block size comparing at offset 0, 1024, 2048 as opposed to
0, 1, 2, 3, 4, 5, 6, etc..

The CRC algorithm has been written in perl for some time now and its
surprisingly fast.

Ive been experimenting with digest algorithms other than MD4 as
I've read collisions have been found with MD4. Ive also experimented
with techniques for representing the digests and crcs in a compressed form
to the host performing the comparison.

Thus far with a 192bit hash and 1024 byte block size (rsync uses 700bytes by
default) there is between a 1% to 3% observed overhead per file which in my
opinion is optimal considering the savings (> 38.8%).

Otherwise if we stick with MD4 (128 bits) the observed overhead is between
1% and 2%.

Regards
Peter Marelas

[BackupPC-users] Backup/Restore Windows Registry

[John Carver <john.carver@mc...>]

My boss just asked me if Backup PC can backup and restore the registry files
on Windows PC's (98, NT, Win2K, etc).
Anyone know the answer?

TIA - John