[OpenAFS] TSM client for OpenAFS

Anders Magnusson ragge@ltu.se
Sun, 05 Apr 2009 21:59:04 +0200

Kristen J. Webb wrote:
> Mattias Pantzare wrote:
>>>>> Of course, but it will still take up much more space. If we do
>>>>> full dump
>>>>> once a week
>>>>> and incs each night there will be many duplicates of files changed
>>>>> early
>>>>> after the full dump :-)
>>>> Do I correctly infer that you don't need a full backup as in
>>>> "ability to
>>>> restore data from arbitrary points in time"?
>>> Well, TSM only store one copy of a specific object, while if you do
>>> full
>>> dumps + incs
>>> there will be multiple copies.
>> Just to be clear, TSM stores one copy per version of a specific object.
> I believe that the path name to the object is part of it's uniqueness.
> It is my understanding that if you rename a directory, that all of the
> files and directories below it will need to be backed up again
> even if they have not changed.
That is depending on the backup client.  The API supports renaming an
in the stored path.  It's up to the backup client to detect the change.

>> If we do full dumps + incs we have to have at least two full dumps in
>> the backup system at a given time.
>> If we do it the TSM way only one copy have to be in the backup system
>> if the file is static.
>> We do need ability to restore data from arbitrary points in time. (I
>> work at the same place as Anders)
> With TSM file mode, you can only restore to points in time
> based on the number of file copies you maintain (e.g. 10).
> So if a single file changes in a volume every day, you can
> only do a complete restore up to 10 days back.  Volume mode
> dumps allow you to do complete restores going back
> further based on the retention policies for your various
> backup levels.
It's possible to specify a time a file should be stored based on policies.
For example, you can store all files at least 31 days or no less than 20
or whatever values selected.

-- Ragge

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