[Beowulf] Rsync - checksums

[Stu Midgley]

That's pretty awesome, are you going to make it available?  or push it
upstream?

If not... how can we get it?

On Tue, Oct 1, 2019 at 1:09 AM Bill Wichser <bill at princeton.edu> wrote:

> Just wanted to circle back on my orginal question.  I changed the rsync
> code adding xxhash and we see about a 3x speedup.  Good enough since it
> is very close to not using any checksum speedups.
>
> Bill
>
> On 6/17/19 9:43 AM, Bill Wichser wrote:
> > We have moved to a rsync disk backup system, from TSM tape, in order to
> > have a DR for our 10 PB GPFS filesystem.  We looked at a lot of options
> > but here we are.
> >
> > md5 checksums take a lot of compute time with huge files and even with
> > millions of smaller ones.  The bulk of the time for running rsync is
> > spent in computing the source and destination checksums and we'd like to
> > alleviate that pain of a cryptographic algorithm.
> >
> > Googling around, I found no mention of using a technique like this to
> > improve rsync performance.  I did find reference to a few hashing
> > algorithms though which could certainly work here (xxhash, murmurhash,
> > sbox, cityhash64).
> >
> > Rsync has certainly been around for a few years!  We are going to pursue
> > changing the current checksum algorithm and using something much faster.
> >   If anyone has done this already and would like to share their
> > experiences that would be wonderful. Ideally this could be some optional
> > plugin for rsync where users could choose which checksummer to use.
> >
> > Bill
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-- 
Dr Stuart Midgley
sdm900 at gmail.com
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