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, Feb 28, 2008 at 11:38:24AM -0000, Azeez Ahamed wrote: > > > It has been observed that when protocol A and B is used, there is > some impact on the I/O performance (especially on sequential writes) > compared to protocol C. But theoretically, protocols A and B should be faster > than C. Why Tiobench results (http://www.drbd.org/performance .html) says that > protocol C is good ? > > Even i carried out performance tests (using Tiobench tool) on 8.0.3 build > and i observed that the results are almost same as the one mentioned on the > DRBD site. > > Please let me know the reason behind it. because those results are horribly out of date? note, kernel 2.4 and DRBD-0.6.6 were used for these tests. protocol A and B implementation was broken then. because there are two aspects to protocol choice in DRBD? * latency * data safety because you measured throughput, and the choice of DRBD protocol has no impact on sustainable throughput? we realy should take that page offline. or better yet, replace with some more recent benchmarks. I'll try to dig some up. with recent 8.0 resp. 8.2, the protocols finally are implemented correct, and indeed show the expected latency improvements: A exposes nearly local latency, B has some latency overhead (order of round-trip-time), C latency overhead is (order of round-trip-time plus some). as mentioned, you trade data safety against latency. -- : Lars Ellenberg http://www.linbit.com : : DRBD/HA support and consulting sales at linbit.com : : LINBIT Information Technologies GmbH Tel +43-1-8178292-0 : : Vivenotgasse 48, A-1120 Vienna/Europe Fax +43-1-8178292-82 : __ please use the "List-Reply" function of your email client.