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Home > Archive > Backup Software > March 2005 > Size of backup drive?
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Size of backup drive?
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| Jordan 2005-03-08, 5:46 pm |
| With a second HDD used for backups, how big does it have to be?
Same size as working HDD, a bit bigger for breathing space, or will
smaller be OK, as it's going to be compressed?
Any advantage to not compressing the backup image?
Jordan
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| Bob Willard 2005-03-08, 5:46 pm |
| Jordan wrote:
> With a second HDD used for backups, how big does it have to be?
>
> Same size as working HDD, a bit bigger for breathing space, or will
> smaller be OK, as it's going to be compressed?
>
> Any advantage to not compressing the backup image?
>
> Jordan
Not all backup apps compress; e.g., NTBACKUP does not. For apps that do
compress, the compression ratio achieved varies a lot; with one backup
app, we got anywhere between 30:1 and 0.95:1 (that's right -- larger
after compression). Compressing files that are already compressed will
make the file grow instead of shrink; .JPGs are an example.
Backup apps use lossless compression, so that a cycle of compression and
expansion should exactly restore (a copy of) the original file. But
beware that what one app compresses cannot usually be expanded by any
other app; in fact, what one app backs up cannot usually be restored
by any other app (a particularly important fact if you plan to migrate
from W9x to XP).
For sizing purposes, the backup HD should be about the same size as
the space allocated on the original HD -- plus or minus what you estimate
as the compression ratio, plus what you expect to see in growth of the
allocated space, plus a fudge factor. Given how cheap large HDs are, my
simple advice is: get a big one.
--
Cheers, Bob
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| Howard Kaikow 2005-03-09, 5:46 pm |
| depends on the software you use and how you will use it.
for example, i have about 64gb of internal drives.
so i got an 80gb external and have 1 backup set on that drive.
i have a 2nd 80gb external drive on which i have a 2nd backup set.
current have about 35gb used on hard drives, so about 30gb is used on the
backup drive.
the 30gb includes a full backup on 26 feb and several incremental backups
since then, plus a small backup set for another computer.
periodically, i do a recycle backup to the backup drive for the main
computer.
--
http://www.standards.com/; See Howard Kaikow's web site.
"Jordan" <jwprincic@optusnet.com.au> wrote in message
news:422e0e1b$0$6166$afc38c87@news.optusnet.com.au...
> With a second HDD used for backups, how big does it have to be?
>
> Same size as working HDD, a bit bigger for breathing space, or will
> smaller be OK, as it's going to be compressed?
>
> Any advantage to not compressing the backup image?
>
> Jordan
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| > But
> beware that what one app compresses cannot usually be expanded by any
> other app; in fact, what one app backs up cannot usually be restored
> by any other app (a particularly important fact if you plan to migrate
> from W9x to XP).
>
That's why I only consider Backup programs which use the standard .zip
format.
=Pete
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| backup-answer_man 2005-03-13, 2:45 am |
| Always get a drive of like size or larger. The size will depend on how
many volumes and type of backup procedures will be stored on this
device.
*** Do Note: The backup and (especially) the compression program will
require local temp space. SO make sure the drive you are backing up
from, has enough allocated space for the creation of temporary files.
***
Compression adds a secondary (& sometimes necessary) layer to perform
your backup. Speed can become an issue depending on the vendor's
compression module.
Do try both compressed and uncompressed and log total backup space and
time. You then will know which option works best for you.
Mark
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