Sage, thanks! I'm missing your email until i saw it in GMANE today. Thanks again! 2015-11-26 21:30 GMT+08:00 Sage Weil <sage@xxxxxxxxxxxx>: > On Thu, 26 Nov 2015, hzwulibin wrote: >> Hi, Sage >> >> I has a question about min_size of pool. >> >> The default value of min_size is 2, but in this setting, when two OSDs >> are down(mean two replicas lost) at same time, the IO will be blocked. >> We want to set the min_size to 1 in our production environment as we >> think it's normal case when two OSDs are down(sure on different host) at >> same time. >> >> So is there anypotential problem of this setting? > > min_size = 1 is okay, but be aware that it will increase the risk of a > situation of a pg history like > > epoch 10: osd.0, osd.1, osd.2 > epoch 11: osd.0 (1 and 2 down) > epoch 12: - (osd.0 fails hard) > epoch 13: osd.1 osd.2 > > i.e., a pg is serviced by a single osd for some period (possibly very > short) and then fails permanently, and any writes during that period are > *only* stored on that osd. It'll require some manual recovery to get past > it (mark that osd as lost, and accept that you may have lost some recent > writes to the data). > > sage > > > > > >> >> We use 0.80.10 version. >> >> Thanks! >> >> >> ------------------ >> hzwulibin >> 2015-11-26 >> >> ------------------------------------------------------------- >> ????"hzwulibin"<hzwulibin@xxxxxxxxx> >> ?????2015-11-23 09:00 >> ????Sage Weil,Haomai Wang >> ???ceph-devel >> ???Re: why my cluster become unavailable >> >> Hi, Sage >> >> Thanks! Will try it when next testing! >> >> ------------------ >> hzwulibin >> 2015-11-23 >> >> ------------------------------------------------------------- >> ????Sage Weil <sage@xxxxxxxxxxxx> >> ?????2015-11-22 01:49 >> ????Haomai Wang >> ???Libin Wu,ceph-devel >> ???Re: why my cluster become unavailable >> >> On Sun, 22 Nov 2015, Haomai Wang wrote: >> > On Thu, Nov 19, 2015 at 11:26 PM, Libin Wu <hzwulibin@xxxxxxxxx> wrote: >> > > Hi, cepher >> > > >> > > I have a cluster of 6 OSD server, every server has 8 OSDs. >> > > >> > > I out 4 OSDs on every server, then my client io is blocking. >> > > >> > > I reboot my client and then create a new rbd device, but the new >> > > device also can't write io. >> > > >> > > Yeah, i understand that some data may lost as threee replicas of some >> > > object were lost, but why the cluster become unavailable? >> > > >> > > There 80 incomplete pg and 4 down+incomplete pg. >> > > >> > > Any solution i could solve the problem? >> > >> > Yes, if you doesn't have a special crushmap to control the data >> > replcement policy, pg will lack of necessary metadata to boot. If need >> > to readd outed osds or force remove pg which is incomplete(hope it's >> > just a test). >> >> Is min_size 2 or 1? Reducing it to 1 will generally clear some of the >> incomplete pgs. Just remember to raise it back to 2 after the cluster >> recovers. >> >> sage >> >> >> -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
