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Re: I don't understand that at least one full backup
2009-08-05 08:22:43
liang cao wrote:
hello
I have read some documents about amanda.I don't understand that at
least one full backup within 7days(if I set dumpcycle 7 days).Is it a
real full backup?
For example,I have directories
(home1,home2,home3,home4,home5,home6,home7) and the dumpcycle is 7
days.As the documents said,amanda will perform a full dump of 1/7th
of all file systems each day, and perform incremental dumps on the
rest of the 6/7th of file systems.
If the day is first day(monday) of the first week,first day to use
amanda,does that mean no incremental dumps on the day ?
Suppose that I want to recover all of my data on tuesday of the second
week,will amanda use the dump image in the first week ?
Suppose that home1 is full backed up on monday,but the full back up of
home1 has been destroyed,does that mean the after 6 days' dump images
can't be used(because they only have the incremental dumps,it's
useless if we don't have the full dump)?
In a word ,I can't understand how to recover the data if amanda use a
different backup scheduling.
Could you describe the exact processes of recovering or give me a
document ?
If the data which is dumping is changed,what will amanda do?
My mother tongue is not English,wish that you could understand my meaning.
thank you!
You seem to be doing just fine with your English.
When you first ask Amanda to back up a particular directory, it will
necessarily do a full backup. As you say, it cannot do an incremental
until it first has a full. Because of this, in a new installation, it
may be a good idea to add a few directories each day until they are all
added to the configuration. Of course, that depends in part on how large
the amount of data in all those directories is in relation to your
backup resources (size of tapes, network bandwidth, server capabilities,
disk space for virtual tapes, etc.)
I would suggest that you have a tape cycle at least twice your dump
cycle, preferably even more. This would ensure that your full backups
don't get overwritten until you have at least one more cycle of full
backups. More redundancy is always better with backups.
Amanda handles the recovery and tells you what tapes it needs (or
recovers from appropriate virtual tapes). From it's indexes, it knows
what full backup to refer back to and which incremental backups should
be applied as well. For example, if I ask Amanda to recover home2 to its
state on August 1, 2009, Amanda will look for the first full backup on
or before that date. It will also look for incremental backups between
the full backup and August 1. Then it will inform me what it needs.
Finally it will proceed to get the full backup recovered and then to get
the incremental backups recovered and apply them to that.
I hope that makes sense.
Good luck. Make use of the wiki -- http://wiki.zmanda.com, and ask the
list if you need more help.
--
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Chris Hoogendyk
-
O__ ---- Systems Administrator
c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~~~~~~~~~ - University of Massachusetts, Amherst
<hoogendyk AT bio.umass DOT edu>
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Erdös 4
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