rsync folks,
Henri Shustak <henri.shus...@gmail.com> wrote:
LBackup always starts a new backup snapshot with an empty directory. I
have been looking at extending --link-dest options to scan beyond just
the previous successful backup to (failed backups / older backups).
However, there are all kinds of edge cases which are worth considering
with such a changes. At present LBackup is focused on reliability as
such, this R&D is quite slow given limited resources. The current
version of LBackup offers IMHO reliable backups of user data and the
scripting sub-system offers a high degree of flxibility.
We recycle directories in our backup scheme, and on tests it is 3
to 6 times faster than creating a new directory tree and then deleting
an old one. Your timing will be different - the speed depends on the relative
numbers of files and directories I'd imagine.
Half our recycled directories are 5 to 6 days old, and our churn rate
is typically only 0.5% of files and 1% of data each day. So, the
recycled directory is usually about 95% right.
Our backup procudures have provision for looking back at previous
directories, but there is not much to be gained with recycled
directories. Without recycling, and after a failure, the latest
available backup may not have much in it, and won't be a good place to
link-dest from - you need to go further back, as Henry is considering.
Yes, every time you start a backup snapshot, a directory is
re-populated from scratch and this takes time with LBackup. However,
if you are seeking reliability then you may wish to check out the
following URL : http://www.lbackup.org
We rarely have a failure with our backups. If we do, our procedure
just re-labels the unfinished directory, and re-syncs as normal on the
next attempt.
And, in another post, Henri Shustak <henri.shus...@gmail.com> gave
good advice on splitting up backups, etc to get performance, for someone
whose original post I didn't find.
Ill take a look but I imagine I cant backup the 80 Million files I
need to in under the 5 hours i have for nightly maintenance/backups.
Currently it's possible by recycling directories...
Here are some performance figures from our backup yesterday. (We have
multiple streams to several filesystems).
The backups completed in 41 minutes.
They transferred:
80533 files out of 18127734 files available (0.4%)
57871616693 bytes out of 6827716377557 bytes available (0.8%)
- so, with this low churn rate, we could backup 80 million files in
about 3 hours.
Our backup target filesystems include SSD and are managed by SGI's DMF.
Hope this helps.
Rob.
Dr Robert C. Bell
HPC National Partnerships | Scientific Computing
Information Management and Technology
CSIRO
T +61 3 9669 8102 Alt +61 3 8601 3810 Mob +61 428 108 333
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