Barry,
i just did a test about that.
if you add another subvolume to the DHT volume and add new files into
an existing directory they will be distributed over all DHT-subvolumes.
I assume that the distribution on old subvolumes will stop when the
free-space threshold is reached, but i did not test that.
Moritz
Am 21.07.2009 um 18:57 schrieb Barry Jaspan:
I have a question about this paragraph from the "Understanding DHT
Translator":
"Currently hash works based on directory level distribution. i.e, a
given file's parent directory will have information of how the hash
numbers are mapped to subvolumes. So, adding new node doesn't
disturb any current setup as the files/dirs present already have its
information preserved. Whatever new directory gets created, will
start considering new volume for scheduling files."
The last sentence suggests that if I have a single directory on a
DHT volume and it is getting full, adding additional subvolumes to
the DHT volume will not help because all the files in a directory
will only ever live in subvolumes that existed at the time the
directory is created. Is that true?
Also, it sounds like an entry mapping each filename (hash number) to
a subvolume is stored in the extended attributes of the parent
directory for that file. What is the practical limit for the number
of files that can be stored in a single directory under this
system? It seems like eventually doing a lookup in the directory's
attributes would itself become a very expensive operation.
Thanks,
Barry
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