Re: I don't understand that at least one full backup

[Chris Hoogendyk]

Amanda will not split up your directory. You decide how to configure 
your disk list entries.


Amanda will start out by backing it up with a full backup. Then the next 
time it will ask for an incremental backup of that directory. An 
incremental backup finds those things that have changed in the directory 
since the last full backup, and then backs up just those things. So, a 
full backup backs up every single item in the directory. An incremental 
backup backs up only those things that have been changed. OK?



---

Chris Hoogendyk

-
  O__   Systems Administrator
 c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~ - University of Massachusetts, Amherst 




--- 


Erdös 4




liang cao wrote:

thank you for answering my questions
but if there is only one directory (even only one file) I want to 
backup (set the dumpcycle 7days), will amanda divide the file into 7 
parts ?

and If the data which is been backed up is changed,what will amanda do?


2009/8/5, Chris Hoogendyk >:



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.


-- 
Chris Hoogendyk

Re: I don't understand that at least one full backup

[Gene Heskett]

On Wednesday 05 August 2009, 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 ?

Only marginally true for a system that is just getting setup.  Once it has 
been running for a while, it will shuffle the backup schedule around so that 
the size of the backups (total size to tape) are more equal on a day to day 
basis.  It will do this by, if there is space on the media, promoting a level 
2 to a level 1, or even a level 0, those dle's that it now knows are smaller 
ones, while not delaying a full level 0 by more than 1 day.  If the media is 
being under-utilized, one can shorten the dumpcycle by one day, which would 
have the effect of making it use 90% of a tape rather than 70% of a tape after 
it has adjusted to the shortened dumpcycle.  But I wouldn't do that without at 
least a months observation & a bit of calculator tapping to see if it will fit 
the media.

I ran with DDS2 tapes for quite a while, and when it worked, the tape filling 
was 95+% every night.  But the service dependability of the DDS2 format 
eventually broke me of that habit, and I have now been running with a vtape 
setup for about 4 years.  Hundreds of times more dependable, random access to 
the backups and now with SATA drives, about 10x faster.

>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 ?

Amanda has all sorts of those abilities.  Reading the man-pages should show 
you how to work that magic.  It will in effect, use all dump images up to that 
date, recovering the last level 0 before the date set, and all incrementals 
between that level 0 and the preset date/time

>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)?

See above.

>In a word ,I can't understand how to recover the data if amanda use a
>different backup scheduling.

Amanda keeps records, and deletes records.  Basically, if you have an existing 
tape that has not, due to the length of the tapecycle set in amanda.conf and 
it has been running for as long as the tapecycle, then amanda has the records 
and can use them.

Here I am using a 1TB SATA drive as the storage medium, dumpcycle is 4 days, 
and tapecycle is 30.  So at any one time I actually have 7.5 full dumpcycles 
of data on hand I can restore from.  So if I delete something and don't find I 
still need it for 3 weeks, then it is still available and recoverable.

>Could you describe the exact processes of recovering or give me a document ?

That is pretty complex.  I would recommend you pull the tarballs from zmanda's 
site, build it, and study the man pages.

   

>If the data which is dumping is changed,what will amanda do?

This is what the 'level's of backups are.  A level 0 is a full image.  A level 
1 is everything that has changed since that level 0.  A level 2 is everything 
that changed since the level 1.  And within the limits of the dumpcycle, could 
even goto level 6 for a 7 day dumpcycle.  OTOH, I don't recall seeing it go 
beyond a level 4.

>My mother tongue is not English,wish that you could understand my meaning.
>thank you!

Your English is good.

-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
The NRA is offering FREE Associate memberships to anyone who wants them.


Habit is habit, and not to be flung out of the window by any man, but coaxed
down-stairs a step at a time.
-- Mark Twain, "Pudd'nhead Wilson's Calendar

Re: I don't understand that at least one full backup

[Chris Hoogendyk]

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.



--
---

Chris Hoogendyk

-
  O__   Systems Administrator
 c/ /'_ --- Biology & Geology Departments
(*) \(*) -- 140 Morrill Science Center
~~ - University of Massachusetts, Amherst 




--- 


Erdös 4