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Re: NT hot backup

From: Andrew Mobbs <andrewm_at_chiark.greenend.org.uk>
Date: 21 Aug 2002 13:00:02 +0100 (BST)
Message-ID: <IDn*Waowp@news.chiark.greenend.org.uk>


Chuck <chuckh_at_softhome.net> wrote:
>
>"Howard J. Rogers" <howardjr2000_at_yahoo.com.au> wrote in message
>news:e7410c46.0208170817.7f3b58d1_at_posting.google.com...
>> You said you wouldn't risk the chance of corrupting a backup by using
>> anything other than OCOPY, yet you are prepared to do precisely that
>> by compressing things! I wouldn't compress an archive if my life
>> depended on it.
>[ bunch of stuff snipped]
>> >Why
>> > should I use if 10g of space for backups when 1g will do?
>>
>> Because you (presumably) don't want to risk your data.
>>
>> Regards
>> HJR
>
>I disagree with your mistrust of compressing backup data. I've been using
>compressed backups for nearly 20 years and never had a problem recovering
>from one whether it be Oracle or something else. Are you aware that all
>modern tape drives use data compression automatically? If I were to accept
>your reasoning for not compressing backups I'd have to stop backing up to
>tape.

The problem with compression is error propagation. If there's minor corruption, then the whole file becomes unrecoverable, rather than just the corrupt block.

Modern tape drives compress each block independently. If there's data corruption, you lose the data in that block, but not subsequent blocks.

-- 
Andrew Mobbs - http://www.chiark.greenend.org.uk/~andrewm/
Received on Wed Aug 21 2002 - 07:00:02 CDT

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