Hello,

I've more then 6000 MD5 hashes, reported by BackupPC_refCountUpdate.
I startet to create empty files with the hash, reported by 
BackupPC_refCountUpdate as missing.
But than it will be reported as poolfile with wrong hash. BackupPC is 
stubborn🤣️.

Currently I'm working on a Perl programm:
- reading all this error hashes from the LOG files
- compare it with the global ../[c]pool/*/poolCnt references
- searching the remaining hashes in the backups 
../pc/<host>/<bckNr>/refCnt/poolCnt.*.*
- search the hashes in the attrib- and index-files of the affected backups
- print a list of files, affected by thus corrupt pool files
- offer to cut this file from the attrib-file or delete the whole backup

I expect to be ready and tested till end of september and I'll send it here 
into the mailing list.

Br
Matthias

Am Montag, dem 03.08.2026 um 14:11 -0400 schrieb Ronald Colcernian:
> Hi Ged,
> 
> Sorry it took a while to get back to you.
> I spend an amount of time running
> BackuPC_refCountUpdate -h <host> -c -f -o 3 
> on all  of my backups as you pointed out in a previous email, they were 
> batched in 11 backups that
> were very old and deletable.
> 
> So now I'd like to clean up this problem. Here is one example of an actual 
> message:
> 2026-08-03 01:22:41  admin : BackupPC_refCountUpdate: ERROR pool file
> /bkpcdata/new_BackupPC_Data/cpool/1c/56/1d5621373a63a74a8872a46f02b40850
> has digest d41d8cd98f00b204e9800998ecf8427e
> instead of 1d5621373a63a74a8872a46f02b40850
> Note that digest d41d8.....427e  is the digest of an empty file.
> 
> I have about 48 of these messages from the last three days.
> I have researched each of these and they all point to a zero sized file.
> 
> Understanding that, I ran the command find cpool -type f -size 0 | wc -l 
> and there are 798 of these zero sized files.
> 
> I have noticed that the nightly while it complains about these cpool file(s), 
> it does not remedy
> it.
> 
> I've spend a while reading backuppc-users email list, and have not really got 
> a good answer, or
> course of action.
> 
> Questions:
> 1) Can I remediate by deleting those files, would be easy with a short bash 
> script.
> 
> 2) Is there a way to take the "has digest number" and find the backup it came 
> from?
> and then delete that backup, perhaps
> 
> 3) I could with a bash script  change the instead of digest  to the zero file 
> size digest.
> 
> What is your best advice?
> 
> Thank you in advance.
> 
> Ron Colcernian
> 
> 
> 
> An important note in my opinion these have accumulated to this extend as a 
> result of
> years of running BackupPC, hard drive failures, rsync  TopDir to a new 
> machine (that was brutal
> BTW), conversion V3 to V4, and gross neglect.
> 
> 
> 
> I ran find cpool 
> 
> 
> On Thu, Jul 23, 2026 at 6:41 PM G.W. Haywood <[email protected]> 
> wrote:
> > Hi there,
> > 
> > Long day today, sorry.
> > 
> > On Thu, 23 Jul 2026, Ronald Colcernian wrote:
> > 
> > > I have 1/2 dozen of these errors in the main BackupPC Log file.
> > > 
> > > Run: I found the following recommendations:
> > > 
> > > BackupPC_refCountUpdate -m -f -c
> > > 
> > > *Questions:*
> > > 1) Is this the proper tool to address this type of error?
> > 
> > Not necessarily.  I'd want to know *why* this has happened.  This tool
> > won't tell you that.  When the problem is fixed, I'd want to know that
> > it has stopped happening.  It's a good tool for that.
> > 
> > The errors are presumably generated and logged by the nightly checks.
> > If you have $Conf{PoolNightlyDigestCheckPercent} at the default 1% per
> > nightly run, each nightly run checks a random 1% of the pool files.
> > If that's the case and you have half a dozen of the errors it could be
> > that there are a lot more waiting to be discovered.  I'd be more than
> > a little uncomfortable with that.  Have you done checks on the storage
> > medium/filesystem(s)?  I'd be wondering about their reliability.  On
> > the systems here I'm almost sure I've never seen this error message.
> > I grepped the last seven years of logs on my busiest backup machine
> > and found none.
> > 
> > > if not what would be the better tool?
> > 
> > You could change the 1% setting (if it is still at the default) to
> > check files more quickly, or try the tool posted in the Wiki here:
> > 
> > https://github.com/guille2306/backuppc_check_pool
> > 
> > it will check all the pool if you want to.  (Strictly speaking the cpool.)
> > 
> > > 2) How long will it take using the tool?
> > > I understand this is a function of the speed of the machine and disk
> > > subsystem.
> > 
> > Hmmmm... perhaps more to the point it will depend on how many pool
> > files there are and how large they are.  Very difficult to say, but
> > you can at least get an idea using the 'progress' option.  Probably
> > with a 3TByte pool it won't be like greased lightning on *anything*.
> > You can stop a test at any time with CTRL-C, it won't break things.
> > That means you can try a test with one set of options and, if looks
> > like it's going to take too long for you stop it and try again with
> > different options.
> > 
> > > I prefer that BackupPC is not shutdown for days.
> > 
> > :)
> > 
> > I'd probably try doing a chunk of checks each day, adjusting 'chunk'
> > to suit the hardware performance and your waking hours. :/
> > 
> > > Can the tool be run by host?
> > 
> > Yes.  If you run it without any options it prints a help page:
> > 
> > 8<--------------------------------------------------------------------------
> > 
> > $ /usr/local/BackupPC/bin/BackupPC_refCountUpdate
> > Usage:
> >    BackupPC_refCountUpdate -h HOST [-c] [-f] [-F] [-o N] [-p] [-v]
> >        With no other args, updates count db on backups with poolCntDelta 
> > files
> >        and computes the host's total reference counts.  Also builds refCnt 
> > for
> >        any >=4.0 backups without refCnts.
> >          -f     - do an fsck on this HOST, which involves a rebuild of the
> >                   last two backup refCnts.  poolCntDelta files are ignored.
> >                   Also forces fsck if requested by needFsck flag files
> >                   in TopDir/pc/HOST/refCnt.  Equivalent to -o 2.
> >          -F     - rebuild all the >=4.0 per-backup refCnt files for this
> >                   host.  Equivalent to -o 3.
> >          -c     - compare current count db to new db before replacing
> >          -o N   - override $Conf{RefCntFsck}.
> >          -p     - don't show progress
> >          -v     - verbose
> >      Notes: in case there are legacy (ie: <=4.0.0alpha3) unapplied 
> > poolCntDelta
> >      files in TopDir/pc/HOST/refCnt then the -f flag is turned on.
> > 
> >    BackupPC_refCountUpdate -m [-f] [-p] [-c] [-r N-M] [-s] [-v] [-P phase]
> >          -m       Updates main count db, based on each HOST
> >          -f     - do an fsck on all the hosts, ignoring poolCntDelta files,
> >                   and replacing each host's count db.  Will wait for backups
> >                   to finish if any are running.
> >          -F     - rebuild all the >=4.0 per-backup refCnt files.
> >          -p     - don't show progress
> >          -c     - clean pool files
> >          -r N-M - process a subset of the main count db, 0 <= N <= M <= 255
> >          -s     - prints stats
> >          -v     - verbose
> >          -P phase Phase from 0..15 each time we run BackupPC_nightly.  Used
> >                   to compute exact pool size for portions of the pool based
> >                   on the phase and $Conf{PoolSizeNightlyUpdatePeriod}.
> > 
> > 8<--------------------------------------------------------------------------
> > 
> > HTH
> > 
> > _______________________________________________
> > BackupPC-users mailing list
> > [email protected]
> > List:    https://lists.sourceforge.net/lists/listinfo/backuppc-users
> > Wiki:    https://github.com/backuppc/backuppc/wiki
> > Project: https://backuppc.github.io/backuppc/




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