On 20/10/15 01:52 PM, Joeri Casteels wrote: > >> On 20 Oct 2015, at 19:20, Digimer <[email protected]> wrote: >> >> On 20/10/15 12:25 PM, Joeri Casteels wrote: >>> >>>> On 20 Oct 2015, at 17:47, Lionel Sausin <[email protected]> wrote: >>>> >>>> Le 20/10/2015 17:30, Joeri Casteels a écrit : >>>>>> Protocol A an async, C is sync. So you're probably hitting the network >>>>>> limit on C. >>>>> I don’t think so since it has a direct 20G trunk in-between with perf i >>>>> get 19.6Gbit/s on single threat. With A (async when i monitor the network >>>>> it also hits 2x the network speed as C does) >>>> "sync" means the round-trip time (down to the remote disks) is what >>>> counts, not the bandwidth. >>> So what causes the 1/2 difference then if i read on forum’s most people >>> don’t even see a speed difference between protocol A and C… btw both’s >>> primary and slave node are identical hardware wise so it’s not that the >>> disks are the limiting factor. >> >> It could easily be the hardware, or configuration, or any number of things. >> >> To diagnose, you'll want to test each node's storage on its own, test >> the network links in isolation, etc. You need to find the location of >> the performance issue (or confirm there is no issue) before you burn >> time debugging higher-level applications like DRBD. >> > I did all the debugging on lower level before posting here, sorry i should > have mentioned this but i thought that was logical :-) > So no bottlenecks on local level and also not on network isolated level… > > >> Protocol A says to call the write complete when it's on the local node's >> network send buffers, so the slow-down could be on the peer's network >> receive buffers. Try testing Protocol B. That calls the write complete >> when it's received by the peer, but not yet committed to persistent storage. > > I tried protocol B and also have the same effect as protocol C so 1/2 > performance drop compared to protocol A… i played with send and receive > buffers but still no change… > I did find a performance increase today with the al-extents but that’s on all > protocols so still end up with 1/2 the performance on protocol B and C.
Strikes me as something to do with the sender's network... Have you tested in the other direction? -- Digimer Papers and Projects: https://alteeve.ca/w/ What if the cure for cancer is trapped in the mind of a person without access to education? _______________________________________________ drbd-user mailing list [email protected] http://lists.linbit.com/mailman/listinfo/drbd-user
