Hi, all,
I used backup tool in Windows 2000 sp4(The one in system tool).
However, I always get prompt to insert another media when I did full
back up on every weekend. It seems that there is not enough space to do
the backup. I am using HP dds-4 data cartridge(40GB*) and the size of
files that I want to back up is about 24GB. It prompts the message when
it backed up about 20GB large. Then I am so confused.

1) The tape says it is 40GB. However, it also says in assuming 2:1
compression. What does it mean?? Is it mean that if no compression
done, the total capacity is 20GB only, right?? If so,

2) I did select hardware compression in my backup job.I checked HP, and
HP says, the tape drive should enable hardware compression by default.
Will hardware compression guarantee that data will be compressed then
write to the tape drive?? and will it be compress in 2:1 ratio??

Sorry for so many question, and I really hope someone can answer me.
Thanks in advance.

Thank you

Regards,
Chi

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chi.jojo@gmail.com wrote:
> Hi, all,
>  I used backup tool in Windows 2000 sp4(The one in system tool).
> However, I always get prompt to insert another media when I did full
> back up on every weekend. It seems that there is not enough space to do
> the backup. I am using HP dds-4 data cartridge(40GB*) and the size of
> files that I want to back up is about 24GB. It prompts the message when
> it backed up about 20GB large. Then I am so confused.
>
> 1) The tape says it is 40GB. However, it also says in assuming 2:1
> compression. What does it mean?? Is it mean that if no compression
> done, the total capacity is 20GB only, right?? If so,
>
> 2) I did select hardware compression in my backup job.I checked HP, and
> HP says, the tape drive should enable hardware compression by default.
> Will hardware compression guarantee that data will be compressed then
> write to the tape drive?? and will it be compress in 2:1 ratio??
>
> Sorry for so many question, and I really hope someone can answer me.
> Thanks in advance.
>
> Thank you
>
> Regards,
> Chi
>

The 2:1 compression ratio is a marketing figure, chosen years ago based
on non-Windows data.  A full backup of a Windows HD is unlikely to get
that, since many files do not compress well.

That tape is good for 20GB; maybe slightly better if you a bunch of .TXT
files (or the like) which compress a lot.  When I backed up to tape, under
W9x and with quite a few compressible files, I generally got 1.25:1.
--
Cheers, Bob

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Thank Bob, So I think I have 2 choices, either use more capacity tape
or backup less files ...

Anyway other choices???

Thanks anyway.

[ Post a follow-up to this message ]

chi.jojo@gmail.com wrote:
> Thank Bob, So I think I have 2 choices, either use more capacity tape
> or backup less files ...
>
> Anyway other choices???
>
> Thanks anyway.
>

Another choice:  get a backup app that supports spanning tapes, so that
the app will write to the end of one tape and then ask you to insert
another tape.  I don't think NTBACKUP supports spanning.
--
Cheers, Bob

[ Post a follow-up to this message ]

Thanks again, Bob.
Ntbackup did ask me to insert new media to the media spool, however, No
matter I input a new tape or the same tape, it also prompts me to
insert the new media tape. ...

Another question, What is the different between copy backup and normal
backup in ntbackup?? The only different I know is copy backup doesn't
clear archive attribute, but normal does. So they also require same
amount of space to backup in the tape right??

Again, thank you very much, Bob. I will contact HP later to ask does
our tape driver support higher capacity tape.

Regards,
Chi

[ Post a follow-up to this message ]

chi.jojo@gmail.com wrote:

> Thanks again, Bob.
> Ntbackup did ask me to insert new media to the media spool, however, No
> matter I input a new tape or the same tape, it also prompts me to
> insert the new media tape. ...
>
> Another question, What is the different between copy backup and normal
> backup in ntbackup?? The only different I know is copy backup doesn't
> clear archive attribute, but normal does. So they also require same
> amount of space to backup in the tape right??
>

I think you're right.

--
Cheers, Bob

[ Post a follow-up to this message ]