DO NOT REPLY [Bug 7854] New: Abysmal sparse file performance

samba-bugs at samba-bugs at
Tue Dec 7 20:09:47 MST 2010

           Summary: Abysmal sparse file performance
           Product: rsync
           Version: 3.0.7
          Platform: x86
        OS/Version: FreeBSD
            Status: NEW
          Severity: major
          Priority: P3
         Component: core
        AssignedTo: wayned at
        ReportedBy: grarpamp at
         QAContact: rsync-qa at

I have a 5.5GB file, mostly sparse. Tar performs far[!] better than rsync.
I have no ideas yet, so just an FYI as to current state.
FreeBSD 8.1 i386 zfs
Yes, I know the blocks used differs but don't know why yet, could
be just how zfs does things or related to the large amount of sparseness.
There are no media errors, CPU/IO load or anything like that and the source
and dest paths are on the same filesystem.
I've not tested times for files that are, say, 90% full instead of 90% sparse
Though a 50% 35MB file was 8.5x slower than tar and had identical
block counts and sha256 with both.

/usr/bin/time rsync -HaxiS ./a ../
>f+++++++++ a
      271.13 real       101.44 user        95.62 sys
ls -sl ./a ../a ; rm -f ../a
blocks bytes
3625 5535932416 ./a
3769 5535932416 ../a

/usr/bin/time tar -cf - ./a | /usr/bin/time tar -C .. -Sxf -
       57.67 real         1.10 user        27.77 sys
       57.67 real        10.68 user         5.87 sys
ls -sl ./a ../a ; rm -f ../a
blocks bytes
3625 5535932416 ./a
2977 5535932416 ../a

Configure bugmail:
------- You are receiving this mail because: -------
You are the QA contact for the bug, or are watching the QA contact.

More information about the rsync mailing list