[tahoe-lafs-trac-stream] [Tahoe-LAFS] #2919: Encourage folks to use a third-party backup tool with Tahoe-LAFS integration instead of `tahoe backup`
Tahoe-LAFS
trac at tahoe-lafs.org
Mon Sep 10 03:37:18 UTC 2018
#2919: Encourage folks to use a third-party backup tool with Tahoe-LAFS
integration instead of `tahoe backup`
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Reporter: exarkun | Owner:
Type: enhancement | Status: new
Priority: normal | Milestone: undecided
Component: code-frontend-cli | Version: 1.12.1
Resolution: | Keywords: tahoe-backup docs
Launchpad Bug: |
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Comment (by tlhonmey):
There are some sizeable tradeoffs to using external backup software.
Duplicity-style full+incremental backups require periodically uploading
your entire dataset, even if all the data is already present, to prevent
the restore chains from becoming infeasibly long. Furthermore, you can't
expire any files out of a backup chain until you do another full, even if
none of their data is in use anymore. So Duplicity will often end up
using significantly more bandwidth and storage.
Systems like Borg that keep things in smaller chunks do better in terms of
bandwidth and storage, but the multiple round-trips needed to update the
various chunk stores and indices result in fairly significant latency
unless all the Tahoe nodes are on your LAN.
Tahoe's built-in backup option does a good job of being bandwidth and
latency efficient, and easily allows expiring old datasets without losing
deduplication, but it loses permissions and xattrs and doesn't have any
built-in retry functionality if grid connectivity is interrupted.
So it all depends on what it is you're backing up. Having some
documentation about which backup programs are known to support Tahoe as a
backing store would be good, but the built-in backup function is not so
terrible that people should necessarily be encouraged to use something
else. With a simple wrapper to detect failed backup attempts and retry it
is more than sufficient for simple data sets and the fact that it knows a
little about Tahoe internals and will perform rudimentary checking on
leases and integrity simplifies its use a little.
--
Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2919#comment:3>
Tahoe-LAFS <https://Tahoe-LAFS.org>
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