On Wed, Jun 7, 2017 at 12:30 PM Jonas Jaszkowic < jonasjaszko...@googlemail.com> wrote:
> > Am 07.06.2017 um 20:29 schrieb Gregory Farnum <gfar...@redhat.com>: > > We prevent PGs from going active (and serving writes or reads) when they > have less than "min_size" OSDs participating. This is generally set so that > we have enough redundancy to recover from at least one OSD failing. > > > Do you mean the min_size value from the crush rule? I set min_size = 2, so > a 2+3 EC pool with 3 killed OSDs still has the minimum amount of 2 OSDs and > should be able > to fully recover data, right? > If you set min_size 2 before taking the OSDs down, that does seem odd. > > In your case, you have 2 OSDs and the failure of either one of them > results in the loss of all written data. So we don't let you go active as > it's not safe. > > > I get that it makes no sense to serve *writes* at this point because we > cannot provide the desired redundancy, but how is preventing me from going > active more safe than just serving *reads*? I think what bugs me is that > by definition of the used erasure code, we should be able to loose 3 OSDs > and still get our data back - which is not the case in this scenario > because our cluster refuses to go active. > Yeah, we just don't have a way of serving reads without serving writes at the moment. It's a limit of the architecture. -Greg PS: please keep this on the list. It spreads the information and archives it for future reference by others. :)
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