[Beowulf] Rsync - checksums
bill at princeton.edu
Mon Sep 30 10:09:29 PDT 2019
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.
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.
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