rsync - Apr 2017 - [Bug 12732] hard links can cause rsync to block or to silently skip files

just subscribed for rsync-qa from bugzilla via rsync
wrote:
> Probably using different options? Can this be some sort of Heisenbug,
> nobody can reproduce? Do the two sequences of shell commands work for
> you as expected? Please note that both rsync commands in the mail
> generated by bugzilla are split into two lines (each): Both rsync
> commands should read
>   
---
Actually, I am reproducing your bug exactly as you entered
it. 

And it is very sensitive to options.

When I take out the $PWD it works.

First your case:
/tmp> rsync -aHvv --compare-dest=$PWD/dstlt/. $PWD/srclt/. $PWD/baklt/. 
|& tee testlt.log
sending incremental file list
delta-transmission disabled for local transfer or --whole-file
./
a is uptodate
d is uptodate
b
a => b
/tmp> ll -i srclt dstlt baklt
baklt:
total 8
17305770 -rw-rw-r-- 2 2 Apr  5 15:46 a
17305770 -rw-rw-r-- 2 2 Apr  5 15:46 b
dstlt:
total 8
8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d
srclt:
total 16
8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
8867 -rw-rw-r-- 2 2 Apr  5 15:46 d
----
Then w/o $PWD:
/tmp> rsync -aHvv --compare-dest=dstlt/. srclt/. baklt/. |& tee
testlt.log
sending incremental file list
--compare-dest arg does not exist: dstlt/.
delta-transmission disabled for local transfer or --whole-file
./
b
d
a => b
c => d
/tmp> ll -i srclt dstlt baklt
baklt:
total 16
17305770 -rw-rw-r-- 2 2 Apr  5 15:46 a
17305770 -rw-rw-r-- 2 2 Apr  5 15:46 b
17305782 -rw-rw-r-- 2 2 Apr  5 15:46 c
17305782 -rw-rw-r-- 2 2 Apr  5 15:46 d
dstlt:
total 8
8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d
srclt:
total 16
8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
8867 -rw-rw-r-- 2 2 Apr  5 15:46 d
--------------

However, if "dstl" is a different file system, it
works:
>  rsync -aHv --compare-dest=~/dstlt/. $PWD/srclt/. $PWD/baklt/. |& tee 
testlt.log  
sending incremental file list
--compare-dest arg does not exist: ~/dstlt/.
./
b
d
a => b
c => d

In my usage both the compare-dest & baklt were 'technically'
different file systems (though the compare-dest was a snap
shot).
-----------
ARG: if baklt is on a different FS, but src+dst are same:
/tmp> rsync -aHv --compare-dest=$PWD/dstlt/. $PWD/srclt/. ~/baklt/. |& 
tee testlt.log  
sending incremental file list
./
b
a => b
/tmp> ll -i srclt dstlt ~/baklt
/home/law/baklt:
total 8
3677653445 -rw-rw-r-- 2 2 Apr  5 15:46 a
3677653445 -rw-rw-r-- 2 2 Apr  5 15:46 b

dstlt:
total 8
8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d

srclt:
total 16
8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
8867 -rw-rw-r-- 2 2 Apr  5 15:46 d

----
Ok... something's screwy here.  But no hangs.

Like I said in my 1st response, if some hard links
were missing in the bak directory, I really would be
unlikely to notice, as I didn't even try to check
them (way too many files), but I never got a hang --
and that's the part I'm thinking might be nfs
related, since I've seen several issues with nfs not
working the same way as a local fs.

I usually use smbfs -- in my usage, it's faster and I
usually have fewer compatibility problems.
(faster meaning ~ Reads~162MB/s, W~220MB/s,
though i've seen explorer hit over 400MB/s).
(using a 10Gb link).

But the above testing shows some unexplained behaviors
out of rsync that sure look like a bug.

Good test case!
:-)

Note that in all --*-dest options if the path is relative it is relative
to the target dir not the "$PWD".  I like to always use absolute paths
because of this.  But essentially, the command with the instances of
$PWD vs without them the paths aren't the same.  If you want all
relative to . paths it would be:
rsync -aHvv --compare-dest=../dstlt/. srclt/. baklt/.

Also, all these params that end with /. the . is kinda pointless despite
being points ;)

On 04/05/2017 07:19 PM, L A Walsh via rsync wrote:
> just subscribed for rsync-qa from bugzilla via rsync wrote:
>> Probably using different options? Can this be some sort of Heisenbug,
>> nobody can reproduce? Do the two sequences of shell commands work for
>> you as expected? Please note that both rsync commands in the mail
>> generated by bugzilla are split into two lines (each): Both rsync
>> commands should read
>>   
> ---
> Actually, I am reproducing your bug exactly as you entered
> it.
> And it is very sensitive to options.
> 
> When I take out the $PWD it works.
> 
> First your case:
> /tmp> rsync -aHvv --compare-dest=$PWD/dstlt/. $PWD/srclt/. $PWD/baklt/.
> |& tee testlt.log
> sending incremental file list
> delta-transmission disabled for local transfer or --whole-file
> ./
> a is uptodate
> d is uptodate
> b
> a => b
> /tmp> ll -i srclt dstlt baklt
> baklt:
> total 8
> 17305770 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 17305770 -rw-rw-r-- 2 2 Apr  5 15:46 b
> dstlt:
> total 8
> 8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
> 8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d
> srclt:
> total 16
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 d
> ----
> Then w/o $PWD:
> /tmp> rsync -aHvv --compare-dest=dstlt/. srclt/. baklt/. |& tee
testlt.log
> sending incremental file list
> --compare-dest arg does not exist: dstlt/.
> delta-transmission disabled for local transfer or --whole-file
> ./
> b
> d
> a => b
> c => d
> /tmp> ll -i srclt dstlt baklt
> baklt:
> total 16
> 17305770 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 17305770 -rw-rw-r-- 2 2 Apr  5 15:46 b
> 17305782 -rw-rw-r-- 2 2 Apr  5 15:46 c
> 17305782 -rw-rw-r-- 2 2 Apr  5 15:46 d
> dstlt:
> total 8
> 8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
> 8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d
> srclt:
> total 16
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 d
> --------------
> 
> However, if "dstl" is a different file system, it works:
>>  rsync -aHv --compare-dest=~/dstlt/. $PWD/srclt/. $PWD/baklt/. |&
tee
> testlt.log  sending incremental file list
> --compare-dest arg does not exist: ~/dstlt/.
> ./
> b
> d
> a => b
> c => d
> 
> In my usage both the compare-dest & baklt were 'technically'
> different file systems (though the compare-dest was a snap
> shot).
> -----------
> ARG: if baklt is on a different FS, but src+dst are same:
> /tmp> rsync -aHv --compare-dest=$PWD/dstlt/. $PWD/srclt/. ~/baklt/.
|&
> tee testlt.log  sending incremental file list
> ./
> b
> a => b
> /tmp> ll -i srclt dstlt ~/baklt
> /home/law/baklt:
> total 8
> 3677653445 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 3677653445 -rw-rw-r-- 2 2 Apr  5 15:46 b
> 
> dstlt:
> total 8
> 8474888 -rw-rw-r-- 1 2 Apr  5 15:46 a
> 8474896 -rw-rw-r-- 1 2 Apr  5 15:46 d
> 
> srclt:
> total 16
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 a
> 8866 -rw-rw-r-- 2 2 Apr  5 15:46 b
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 c
> 8867 -rw-rw-r-- 2 2 Apr  5 15:46 d
> 
> ----
> Ok... something's screwy here.  But no hangs.
> 
> Like I said in my 1st response, if some hard links
> were missing in the bak directory, I really would be
> unlikely to notice, as I didn't even try to check
> them (way too many files), but I never got a hang --
> and that's the part I'm thinking might be nfs
> related, since I've seen several issues with nfs not
> working the same way as a local fs.
> 
> I usually use smbfs -- in my usage, it's faster and I
> usually have fewer compatibility problems.
> (faster meaning ~ Reads~162MB/s, W~220MB/s,
> though i've seen explorer hit over 400MB/s).
> (using a 10Gb link).
> 
> But the above testing shows some unexplained behaviors
> out of rsync that sure look like a bug.
> 
> Good test case!
> :-)
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
-- 
~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,
	Kevin Korb			Phone:    (407) 252-6853
	Systems Administrator		Internet:
	FutureQuest, Inc.		Kevin at FutureQuest.net  (work)
	Orlando, Florida		kmk at sanitarium.net (personal)
	Web page:			http://www.sanitarium.net/
	PGP public key available on web site.
~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,-*~'`^`'~*-,._.,

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Kevin Korb via rsync wrote:
> Note that in all --*-dest options if the path is relative it is relative
> to the target dir not the "$PWD".  I like to always use absolute
paths
> because of this.  But essentially, the command with the instances of
> $PWD vs without them the paths aren't the same.  If you want all
> relative to . paths it would be:
> rsync -aHvv --compare-dest=../dstlt/. srclt/. baklt/.
>   
---
    Good point -- though it still doesn't explain the differing
output when dstlt or baklt are on different file systems (one
works, while the other was worse)....