Re: [BackupPC-users] Conf{PoolNightlyDigestCheckPercent} on btrfs and zfs

[Guillermo Rozas]

>
> One ensures against file system bit rot, the other ensures backup file
> consistency.
>

I would say $Conf{PoolNightlyDigestCheckPercent} = 1 is also a check for
bit rot, as the only thing it does is to read the file, re-calculate the
md5 checksum, and compares it with its name (which is the md5 calculated at
the time of writing). It actually says it in the help, "This is check if
there has been any server file system corruption."

What controls the consistency of the backup are
$Conf{PoolSizeNightlyUpdatePeriod} and specially $Conf{RefCntFsck}.

Regards,
Guillermo
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Re: [BackupPC-users] Problem with WakupSchedule and Backupplan

[Les Mikesell]

On Tue, May 4, 2021 at 10:24 AM Ralph Sikau  wrote:
>
> I have a large media library which is too big to be backed
> up on a single day. That's why I'd like to split up the real
> host in several virtual hosts each defining a special part
> of the library and being backed up at night on a special day
> of the week. The PCNightlyJobs shall run during daytime.
> Can you give me an example of a correct configuration for
> this? Thanks in advance!
>

One approach to this is to make up several hostnames for your virtual
hosts, using $Conf{ClientNameAlias} to point them to the correct real
host.  Then use includes/excludes to specify the directories you want
each to contain and the blackout periods to define the times you do
not want each to be backed up - leaving the window you want for each
so normal scheduling will queue them.   Just be aware that if you only
include specific directories you may miss later additions or changes
on the host.

-- 
   Les Mikesell
 lesmikes...@gmail.com


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Re: [BackupPC-users] Conf{PoolNightlyDigestCheckPercent} on btrfs and zfs

[Michael Huntley]

On 2021-05-04 00:45, Ghislain Adnet wrote:
No, because that's like turning off the airbags on your car because 
you already have seatbelts.


thanks for your answer, i am trying to understand more about this.

If this check is to prevent bitrot or disk corruption of an existing
file, and if rsync is sure the file is ok, and then that ZFS keep the
checksum
and guarantee that the file did not change (assuming raidz1 at least
of course) then, at the end what could be the case where this check
help find issue ?

--
cordialement,
Ghislain


One ensures against file system bit rot, the other ensures backup file 
consistency.


Cheers!

mph


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Re: [BackupPC-users] Problem with WakupSchedule and Backupplan

[Ralph Sikau]

Thanks, Adam, for the detailed explanation. Just one more
question:
What happens if $Conf{BackupsDisable} is set to 1 and the
backup of Host A is started on Monday and of Host B on
Tuesday each at a given time by a cron job? How does this
interact with the WakeupSchedule?
I have a large media library which is too big to be backed
up on a single day. That's why I'd like to split up the real
host in several virtual hosts each defining a special part
of the library and being backed up at night on a special day
of the week. The PCNightlyJobs shall run during daytime.
Can you give me an example of a correct configuration for
this? Thanks in advance!

Regards, Ralph



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Re: [BackupPC-users] Problem with WakupSchedule and Backupplan

[Adam Goryachev via BackupPC-users]

On 4/5/21 22:00, Ralph Sikau wrote:

Am Mittwoch, den 28.04.2021, 16:30 + schrieb backuppc-
users-requ...@lists.sourceforge.net

:

However, I have a suspicion that you are on the right track.  If a backup is 
missed, then it is put into the queue and it will start as soon as it is able 
to.  You may be able to use the blackout hours to help.

Greg,
I think it would help if I could get answers to these
questions:
1. For how long does the backup system STAY awake after
having been awakened according to the WakeupSchedule?

Until the queue is empty.

2. When a backup starts at 11:30 pm will it go on then over
midnight during the following night or will ist go on hold
at midnight?
A started backup will continue until finished regardless of blackout 
periods etc.

3. Is there a possibility to see what is hold in the backup
queue?

Yes, on the web interface, click "Current Queues"

Maybe you have the answers.


More information:

When backuppc wakes up, it will put all hosts that are due to be backed 
up on the queue (ie, their backup schedule and last backup completed 
times are too far apart). It will then take the number of jobs from the 
queue that your config says it can run in parallel, and starts them. If 
a backup starts but is inside the blackout winder, then it is 
immediately stopped (ie, it never really actually starts the xfer), and 
is removed from the queue. Same if the ping time is too long, or 
whatever other constraint that suggests the backup has failed/can't 
start. The next backup on the queue will then start. Eventually, all 
backups on the queue will complete, and backuppc goes back to sleep.


If the backups took too long, and continued past the next wakup period, 
then all due hosts not already on the queue will be added to the queue. 
This is why you can set wakeup schedule every 5 minutes, without causing 
a problem. The wakeup schedule basically just defines the minimum amount 
of time after a backup becomes due, before the backup will be placed on 
the queue.


Regards,
Adam

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Re: [BackupPC-users] Problem with WakupSchedule and Backupplan

[Ralph Sikau]

Am Mittwoch, den 28.04.2021, 16:30 + schrieb 
backuppc-users-requ...@lists.sourceforge.net:
> However, I have a suspicion that you are on the right
> track.  If a backup is missed, then it is put into the
> queue and it will start as soon as it is able to.  You may
> be able to use the blackout hours to help.

Greg,
I think it would help if I could get answers to
thesequestions:1. For how long does the backup system STAY
awake afterhaving been awakened according to the
WakeupSchedule?2. When a backup starts at 11:30 pm will it
go on then overmidnight during the following night or will
ist go on holdat midnight?3. Is there a possibility to see
what is hold in the backupqueue?Maybe you have the answers.
Thanks, Ralph
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Re: [BackupPC-users] Conf{PoolNightlyDigestCheckPercent} on btrfs and zfs

[Ghislain Adnet]

No, because that's like turning off the airbags on your car because you already 
have seatbelts.


thanks for your answer, i am trying to understand more about this.

If this check is to prevent bitrot or disk corruption of an existing file, and 
if rsync is sure the file is ok, and then that ZFS keep the checksum
and guarantee that the file did not change (assuming raidz1 at least of course) 
then, at the end what could be the case where this check help find issue ?

--
cordialement,
Ghislain
--
cordialement,
Ghislain ADNET.
AQUEOS.


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