Hi,
On 12/11/2009 11:19 AM, Mark Watts wrote:
On Thu, 2009-12-10 at 16:58 +0100, Florian Haas wrote:
Lars beat me to this but anyway...
On 2009-12-10 13:23, Beck Ingmar wrote:
Hi Florian,
why improves bonding of the replication-connection not the performance.
I did not say that. :) I said round-robin bonding _over 4 NICs_ would be
detrimental to performance.
We currently have a direct connection for the 1 Gb DRBD replication and
I
wanted to activate an active-active bonding (with a further LAN-port). I
would expect nearly double of replication-performance.
All of the following applies to DRBD Connected in protocol C:
- With 1 GBit Ethernet link, you can do about 110 MB/s (provided your
storage subsystem has that bandwidth);
- With 2 GBit links bonded in round-robin mode, you top out at around
160-170 MB/s (even then you may have to tune kernel TCP parameters);
- with 3 Gbit links, your throughput will drop down to around 110 MB/s;
- with 4 links or more, you will get _significantly less_ throughput
than a single unbonded link.
Reason for all this: TCP reordering.
Or depends it on whether the connection between the nodes directly or
via 1-n switches.
I am talking about back-to-back connections. Switches could make it worse.
Do Jumbo Frames make any difference here?
Yes they help, in both cases (with switch and in b2b scenario). Please
test everything and put everything working without jumbo frames. Use
jumbo frames only if you need extra performance and after you have
everything working.
But there are some other settings, search in google for "linux kernel
tcp optimizations".
Mark.
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