[Zope] Backing up Data.fs

[Peter Sabaini]

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Toby Dickenson wrote:
> On Monday 02 June 2003 12:48, Peter Sabaini wrote:
> 
>>Toby Dickenson wrote:
>>
>>>On Monday 02 June 2003 10:18, Peter Sabaini wrote:
> 
> 
>>>Think
>>>of backup as a database operation  -  this script has no ACID.
>>
>>please explain -- why would i need transactions and concurrency with a
>>backup script?
> 
> 
> Suppose this morning (Monday) the machine locks up (or power failure, or 
> network loss if this is on a network mount, etc) immediately after this 
> backup script has terminated. Some, but not all of the changes to 
> /archive/monday/data.fs will have been written to disk, and some will have 
> been lost. There is every chance that todays backup has been mashed together 
> with the backup from last weeks monday in some arbitrarily confusing way. 
> There is no new backup, and the old backup has been destroyed.
> 
> Sure, if this happens only once then this script leaves you with six other 
> good daily copies. But during a disaster recovery is the worst possible time 
> to have to be thinking about which "backup" directory contains a data.fs that 
> has recently been destroyed by a non-transactional backup script. Sean Upton 
> talks about disaster-prepardness here:
> http://zope.nipltd.com/public/lists/zope-archive.nsf/AGByKey/6036CE8DFC2D3484
> 
> This "bug" can be fixed for FileStorage backup scripts, check out the link I 
> posted earlier. The cost is in performance.

i see. i guess it mainly depends on how write-heavy your zope 
application is.  but if this is okay for you i'd like to put up the 
script you linked to as a comment as soon as the book is online.


[snip]


  - peter.



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