Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On 02/09/2011 12:21 PM, ionral wrote: > > > > Felix Frank-2 wrote: >> >> Hi. >> >>> if I check the status of drbd the following response is: >>> >>> 0: cs: Connected ro: Primary / Primary ds: UpToDate / UpToDate C r ---- >>> ns: 640864680 nr: 135234784 dw: 776099464 dr: 1520599328 al: 836478 >>> bm: >>> 2185 lo: 0 pe: 0 ua: 0 ap: 0 ep: 1 wo: b OOS: 0 >>> >>> I do not know if it is positive that the method is to write after is >>> Barrier >>> .... reading the manuals of drbd I noticed that in these cases (BBU) >>> performance would be better for a wo:n >>> >>> What do you think? >> >>>> Possibly? You may want to just test the performance difference. >> >> so there is no certainty that it is more powerful >> I can just do a test I didn't say that. *I* don't have any certainty because I never tried it. If the documentation states that there is a performance gain, there is no reason to believe otherwise. I'm just not handing out confirmations about things I'm clueless about. >> >>> more to this I can tell you that another hardware configuration with a >>> simple SATA disks in software raid 0 configuration (sda and sdb) and >>> without drbd.conf options: no-disk-flushes -no-md-flushes, The drbd uses >>> instead the drain ... that seems to be dangerous without a BBU, but the >>> drbd >>> has preferred this choice, and not clear to me ... >> >>>> Check you kernel logs. DRBD may have noticed that barriers are not >>>> available for your backing device and thus falls back to drain. Is LVM >>>> involved in your that setup per chance? >> >>>> Regards, >>>> Felix >> >> Unfortunately I have nothing in the logs, the rotate deleted the old log, >> but do not understand much because the drbd not find in my backing storage >> support for the barrier, I use LVM on top of drbd and not vice versa, is >> not this strange thing? The setup is fine. If it's not painful for you, you may want to bring the resource down and up again, watch the /proc/drbd output and if it drops from using flush, check your logs again. Except someone comes up with a better idea about why you're on drain. HTH, Felix