Hi Eric,
I've seen client-side dedup be slower on 1Gb/s networks every time I test
it, every single time.
It doesn't surprise me at all just looking at the added latency to check if
a chunk is already in Spectrum Protect or not, sending it via the network,
network latency (big one), reading form the database and than all the way
back to the client has got to be a LOT slower than doing it all in the
server, at least when the local cache isn't very effective and with two
million files I doubt it is very effective (but I don't know this, haven't
done enough testing with different data source types).
Network latency on a round trip alone probably adds a lot of time (% wise)
to just a local SSD database read alone, SSD's have a latency of
0.0something ms and everything stay's in compute with server side dedup.
I only use client-side dedup with WAN networks or when I test and would see
that the speeds are comparable, I think this would be due to a very low
latency network but I wonder if others here have done more testing on this.
I believe that when you have very heavy loads you can put more in the
server in an night of backups because there is a smaller load on the server
because the clients do some work but again, I only use it when sending data
thru WAN connections, for those scenario's it's perfect especially in
combination with 8.1 B/A client-side compression.
On Fri, May 12, 2017 at 1:52 PM, Loon, Eric van (ITOPT3) - KLM <
Eric-van.Loon AT klm DOT com> wrote:
> Dear TSM-ers,
> We are almost in production with our first directory containerpool TSM
> server. We did a lot of testing with client vs server-side dedup and
> overall client-side was faster. But not on one of our Linux clients. This
> machine has a filesystem with nearly two million files, total amount of
> data is 227 GB. The server backs up through 1Gb Ethernet and with
> server-side dedup the backup takes 03:54. With client-side dedup enabled,
> the backup runs for 12:02! The client contains 16 CPU's and average
> utilization is no more than 10%. No swapping during a backup.
> I opened a PMR, but the support offices tries to convince me that
> client-side dedup is slower (twice as slow) by default. I really have a
> very hard time believing this. What is your experience with client-side
> dedup in combination with a large amount of smaller (approx. 1 Mb) files?
> Thanks for any help in advance!
> Kind regards,
> Eric van Loon
> Air France/KLM Storage Engineering
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