Jim Leonard wrote at about 19:45:57 -0500 on Tuesday, August 18, 2009:
> Holger Parplies wrote:
> > first of all, where are you seeing these figures, and what are you
> measuring?
>
> Rather than try to convince you of my competence, I will offer up these
> benchmarks for the exact same endpoint machines and file (a 2 gigabyte
> uncompressable *.avi file that did NOT exist on the target):
>
> Unix rsync->Unix rsync: 60MB/s
> Windows SMB->Unix smbclient: 65MB/s
> Windows rsyncd->Unix rsync: 5MB/s
> Windows rsyncd->BackupPC_dump: 5MB/s
>
> As you can see, something is now clearly wrong with the windows rsyncd
> source. I confirmed this by profiling actual rsync in Unix and saw that
> 77% of its time was spent waiting for data (which mirrors exactly what
> File::RsyncP::pollsys was doing, wasting 77% of its time waiting for
> data). So the problem isn't BackupPC, it's windows rsyncd.
>
> I initially used cygwin rsync; for the above test, I switched it out for
> DeltaCopy's rsync. BOTH VERSIONS had this kind of crappy speed. Both
> versions showed hardly any CPU or filesystem usage; they just simply run
> slowly for a reason I can't figure out. The network isn't slow (gigabit
> ethernet), the checksums aren't taking a long time (it's a brand new
> file that doesn't exist on the target so there's nothing to checksum),
> the hard drive isn't slow (raid-0 SATA stripe capable of 130GB/s read
> speeds) -- it just simply serves data really really slowly.
>
I believe that I have noticed similar behavior with rsyncd processes
throttled down to near 0% cpu on Windoze machines and backups taking
similarly long.
> I can't believe this is an isolated incident. Other people have got to
> be seeing this. Other than cygwin and DeltaCopy, is there any specific
> version of rsyncd I should be using? Any flags I can set in BackupPC
> that can improve speed?
>
> > The primary purpose of the rsync protocol is to save network
> bandwidth. So if,
> > for example, you are transferring only one tenth the amount of data
> for a full
> > backup, and that takes the same time as with SMB, your network
> throughput will
>
> These are not incrementals, but full backups, and the speed as
> previously mentioned is 1/10th that of SMB. SMB backups are quite fast
> on this same infrastructure (around 65MB/s) but I can't use SMB because
> of XP/Vista/Win7 permission problems.
>
> > I believe Craig is researching other alternatives (a fuse FS to handle
> > compression and deduplication, so BackupPC could, in fact, use native
> rsync).
>
> I hope that doesn't become mandatory, because that would limit BackupPC
> to Unix versions that support FUSE (not all do).
> --
> Jim Leonard (trixter AT oldskool DOT org) http://www.oldskool.org/
> Help our electronic games project: http://www.mobygames.com/
> Or check out some trippy MindCandy at http://www.mindcandydvd.com/
> A child borne of the home computer wars: http://trixter.wordpress.com/
>
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