Re: Backup to DVD

| In article <[email protected]>, [email protected] 
| (D . Thomas Podnar) wrote:
| 
| > > In article <[email protected]>, 
| > > [email protected] (D. Thomas Podnar) wrote:
| > > 
| > > > The new compressor in BackupEDGE 2.0 will probably allow 10GB-12GB
| > > > to be stored on one piece of 4.7GB media in a typical Linux
| > > > installation. Above that, I'd probably suggest tape.
| > > 
| > On Tue, Dec 02, 2003 at 10:34:00PM +0000, Ed Form wrote:
| > 
| >   7.5Gig tops.
| >  
| >   Ed Form
| > 
| > 
| > Hi Ed.
| > Please explain.
| > Tom Podnar
| > Microlite
| 
| Anyone who banks on a finished backup compression of better than 1.5 to 1 
| for a whole server is going to be dissapointed. I'd be more than happy to 
| be proved wrong but I don't think it likely.
| 
| Ed Form


HMMM. I guess I'll try to make you happy then. Let's look at some
information.

Oh, anyone not interested in backups and/or compression, this is the time
to bail.


Basis for Discussion:
=====================
The hardest thing to compress during a backup, or at any other time,
is a base operating system. It's got LOTS of things that don't like
to be compressed, contain no data, or are already compressed.

BackupEDGE Compression:
=======================
Our compression is on a file-by-file basis. Much safer that trying to
pipe an entire archive through a compressor, and fully compatible
with verification, encryption, quick file access, etc.


It happens that I just completed a test install of Red Hat Enterprise
Linux 3 WS, using all of the defaults. Nothing else is installed
but BackupEDGE 2.0.

There are roughly 114,964 entities to be archived, which consume
around 1.88GB in our standard archive format.

There are 28,925 device nodes, links, directory entries, etc. that
don't count as physical space but take 14.17MB to archive.

There are 40,221 files of either 0 length or containing less than
4 blocks of data that aren't worth compressing. These take
61.07MB to archive.

There are 3,855 files greater than 4 blocks long, but already
compressed using bzip2 or gzip, which our compressor ignores.
These take 43.39MB to archive.

That leaves us with around 42,000 files which can be compressed as
we do a backup.


Here is a summary from a full system backup of that system, which
means of course all of the items listed above.


Date                   = Tue Dec 02 21:32:51 2003
Files Encountered      = 114964
Total Data             = 1.88GB
Data Written           = 829.21MB
Volume Left            = 3.45GB
SW Compression         = 64%
Elapsed Time           = 00:06:49
Data Transfer Speed    = 2124235 bytes/sec
Net Transfer Rate      = 121.70 MB/min
Exit Status            = 0


Even with all that non-compressible overhead, we managed to get a
backup which SHOULD have taken 1,925.12MB (1.88GB) and fit it into
829.21MB on a DVD-RAM drive.

The capacity of a DVD-RAM is 4,368.375MB. If we extrapolate these numbers
to a full DVD, we'd get 10,141MB or roughly 9.90GB. And that is from
stuff that doesn't usually compress well.


Unless a system is being used exclusively to archive already-compressed
data, we expect that user applications and data will compress at
much higher ratios than system files.

So I'm well prepared to stand by my statement and document it.


Anyone wanting to provide some details on their live systems is
welcome to install our evaluation product. If you have a tape drive,
set BackupEDGE up to use software compression instead of the default
hardware compression, do a Master Backup, and post your summary here.


Regards,
Tom
---
  D. Thomas Podnar - President  [email protected]
  Microlite Corporation         724-375-6711 Voice
  2315 Mill Street              724-375-6908 Fax
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+---------------------------------------------------------+
|Makers of BackupEDGE 2.0 - Backup and Disaster Recovery  |
|Software for Unix and Linux Systems - Now With Encryption|
|Supports: Tape Drives, Libraries, CD/DVD Optical Media   |
|http://www.microlite.com          ftp://ftp.microlite.com|
+---------------------------------------------------------+

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