[tahoe-dev] timestamps on mutable files

Jody Harris imhavoc at gmail.com
Mon Jan 4 15:37:44 UTC 2010


Oh, I forgot to answer the "how?"

... put --mutable ...

jody
----
- Think carefully.
- Contra mundum - "Against the world" (St. Athanasius)
- Credo ut intelliga - "I believe that I may know" (St. Augustin of Hippo)


On Sun, Jan 3, 2010 at 10:59 PM, Jody Harris <imhavoc at gmail.com> wrote:

> I have a script that:
>  - iterates though my MySQL tables
>  - dumps each table
>  - pipes the dump through gzip
>  - write the file to a temp file
>  - copies the file to [remote storage] (now Tahoe grid)
>  - deletes temp file
>
> This gives me a daily snapshot of all of the active databases on my server
> every night.
>
> The current backup is ~ 300 MB/night, which isn't bad, but after one year,
> that's 110+GB x 3.3 and counting of consumed tahoe space. Unless tahoe has a
> better garbage collection system than I have come to believe, that's going
> to be a problem on a 500 GB grid.
>
> In my reading of the tahoe docs, I have not come across any alarms
> concerning mutable files. Is there something I should be made aware of?
>
> jody
> ----
> - Think carefully.
> - Contra mundum - "Against the world" (St. Athanasius)
> - Credo ut intelliga - "I believe that I may know" (St. Augustin of Hippo)
>
>
> On Sun, Jan 3, 2010 at 10:50 PM, Zooko O'Whielacronx <zookog at gmail.com>wrote:
>
>> On Sun, Jan 3, 2010 at 10:33 PM, Jody Harris <havoc at harrisdev.com> wrote:
>> > I have set up my web server to store backup files on my tahoe grid,
>> shifting
>> > from the use of a server at my house. One thing that initially alarmed
>> me
>> > was that the timestamps of the backed up files is not updated in the
>> > tahoe-lafs interface. I did confirm that the shares timestamps are
>> updated.
>>
>> Tahoe-LAFS doesn't store timestamps or other metadata on files, only
>> on links to files, which links are stored in directories.  So if you
>> have a directory which contains a link named "README.txt" to version 1
>> of your file, and then you upload version 2 of your file and you
>> change that directory to link to version 2, then Tahoe-LAFS will
>> update the timestamp on that link named "README.txt" when it updates
>> the link to point to the new file.
>>
>> Did you say "mutable files"?  You should probably not be using mutable
>> files for anything.  Immutable files (plus directories) probably fit
>> all your needs for backups, and mutable files have significant
>> performance problems.
>>
>> How do you trigger these backups -- are you using "tahoe cp" or "tahoe
>> backup" or sending HTTP requests to the WAPI or something else?
>>
>> Regards,
>>
>> Zooko
>> _______________________________________________
>> tahoe-dev mailing list
>> tahoe-dev at allmydata.org
>> http://allmydata.org/cgi-bin/mailman/listinfo/tahoe-dev
>>
>
>
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