[DRBD-user] performance issues with DRBD :(

Jakov Sosic jakov.sosic at srce.hr
Thu Dec 10 17:00:05 CET 2009

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.

On Thu, 2009-12-10 at 16:52 +0100, Lars Ellenberg wrote:

> This likely has been correct at some point in time, or for 100 MBit/s.
> In my experience, bonding two 1GBit links can yield about 1.7 to 1.8,
> adding the third drops back to about 1.0 but adds latency,
> and adding a forth will deteriorate to less then a single link.
> This is for a _sinlge_ tcp bulk transfer.  Of course, the sum total over
> all transfers on those bonded links will be higher.
> But for the single tcp bulk transfer, in my experience, more than two
> 1GBit links in bonding-rr are counterproductive.
> May be highly variable with different NICs, boards,
> processors and bus and processor speeds.

I've tested the network and there is no evident problems with netcat
transfers. Also, i don't see how high disk IO on secondary can be result
of the network interfaces, because according to atop, interfaces are
loaded only approx 1-3% each. 

I've tried LACP too, and I have exact the same problems with drbd. When
DRBD is disconnected, device gives me double to triple performance, also
changing from protocol C to A or B gives no significant improvement.

|    Jakov Sosic    |    ICQ: 28410271    |   PGP: 0x965CAE2D   |
|                                                               |

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