Re: [BackupPC-users] Question about "link pending".

Bruno Faria wrote:
> Hi,
>
> I've posted a similar a question before but since I didn't get any response
> the first time, I guess I'll try again . :)
>   

You might be edified by reading the documentation 
(http://backuppc.sourceforge.net/faq/BackupPC.html).  I highly recommend 
the section detailing how the software works 
(http://backuppc.sourceforge.net/faq/BackupPC.html#backuppc_operation).  
If you are not the document reading type, I have excerpted some 
pertinent details below...

> For some reason I'm getting alot of "link pending". During the first backups
> I didn't have any problem with link pending since once a backup was done it
> would be done without any link pending. But whenever BackupPC_Nightly
> started, all the backups are getting "link pending" for hours and hours
> (about 7+ hours of link pending for each host).
>
> So here are my questions:
>
> 1) Is it normal for links to be pending this long?
>   

 From the document section on $Conf{MaxBackupPCNightlyJobs} (under 
http://backuppc.sourceforge.net/faq/BackupPC.html#general_server_configuration):

"Each night, at the first wakeup listed in $Conf{WakeupSchedule} 
<http://backuppc.sourceforge.net/faq/BackupPC.html#item__conf_wakeupschedule_>, 
BackupPC_nightly is run. Its job is to remove unneeded files in the 
pool, ie: files that only have one link. To avoid race conditions, 
BackupPC_nightly and BackupPC_link cannot run at the same time."

> 2) Would it be bad if I just increase the max amount of "link pending" on
> the config.pl file to allow about 20+ pending links?
>   

Personally, I have "$Conf{MaxPendingCmds} = 50;"  My nightly job* (which 
removes between 6 and 9 GB of data from  a pool size of about 240GB on a 
pair of software mirrored SCSI drives) is currently taking between 9 and 
14 hours.  I get close to 30 link jobs queued, and they all clear out 
less than an hour after the nightly job finishes.  Since I run all my 
backups at night (blackout period of 07:00 to 19:30) I'll probably wind 
up making the "nightly" job run in the morning.

> 3) What's the job of "link pending"?
>   

Also from the docs :

"BackupPC_link reads the NewFileList written by BackupPC_dump and 
inspects each new file in the backup. It re-checks if there is a 
matching file in the pool (another BackupPC_link could have added the 
file since BackupPC_dump checked). If so, the file is removed and 
replaced by a hard link to the existing file. If the file is new, a hard 
link to the file is made in the pool area, so that this file is 
available for checking against each new file and new backup."

> Thanks for help in advance!
>
> --Bruno

Hope this helps.

Chris

* Using the term job loosely here, as I personally have 
$Conf{MaxBackupPCNightlyJobs} = 8.

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