In my test it was just recovering some replicas not the whole osd. Am 22.11.2012 um 16:35 schrieb Alexandre DERUMIER <[email protected]>:
>>> But who cares? it's also on the 2nd node. or even on the 3rd if you have >>> replicas 3. > Yes, but rebuilding a dead node use cpu and ios. (but it should be benched > too, to see the impact on the production) > > > > ----- Mail original ----- > > De: "Stefan Priebe - Profihost AG" <[email protected]> > À: "Alexandre DERUMIER" <[email protected]> > Cc: "ceph-devel" <[email protected]>, "Mark Kampe" > <[email protected]>, "Sébastien Han" <[email protected]>, "Mark > Nelson" <[email protected]> > Envoyé: Jeudi 22 Novembre 2012 16:28:57 > Objet: Re: RBD fio Performance concerns > > Am 22.11.2012 16:26, schrieb Alexandre DERUMIER: >>>> Haven't tested that. But does this makes sense? I mean data goes to Disk >>>> journal - same disk then has to copy the Data from part A to part B. >>>> >>>> Why is this an advantage? >> >> Well, if you are cpu limited, I don't think you can use all 8*35000iops by >> node. >> So, maybe a benchmark can tell us if the difference is really big. >> >> Using tmpfs and ups can be ok, but if you have a kernel panic or hardware >> problem, you'll lost your journal. > > But who cares? it's also on the 2nd node. or even on the 3rd if you have > replicas 3. > > Stefan > > >> ----- Mail original ----- >> >> De: "Stefan Priebe - Profihost AG" <[email protected]> >> À: "Mark Nelson" <[email protected]> >> Cc: "Alexandre DERUMIER" <[email protected]>, "ceph-devel" >> <[email protected]>, "Mark Kampe" <[email protected]>, >> "Sébastien Han" <[email protected]> >> Envoyé: Jeudi 22 Novembre 2012 16:01:56 >> Objet: Re: RBD fio Performance concerns >> >> Am 22.11.2012 15:46, schrieb Mark Nelson: >>> I haven't played a whole lot with SSD only OSDs yet (other than noting >>> last summer that iop performance wasn't as high as I wanted it). Is a >>> second partition on the SSD for the journal not an option for you? >> >> Haven't tested that. But does this makes sense? I mean data goes to Disk >> journal - same disk then has to copy the Data from part A to part B. >> >> Why is this an advantage? >> >> Stefan >> >>> Mark >>> >>> On 11/22/2012 08:42 AM, Stefan Priebe - Profihost AG wrote: >>>> Am 22.11.2012 15:37, schrieb Mark Nelson: >>>>> I don't think we recommend tmpfs at all for anything other than playing >>>>> around. :) >>>> >>>> I discussed this with somebody frmo inktank. Had to search the >>>> mailinglist. It might be OK if you're working with enough replicas and >>>> UPS. >>>> >>>> I see no other option while working with SSDs - the only Option would be >>>> to be able to deaktivate the journal at all. But ceph does not support >>>> this. >>>> >>>> Stefan >>>> >>>>> On 11/22/2012 08:22 AM, Stefan Priebe - Profihost AG wrote: >>>>>> Hi, >>>>>> >>>>>> can someone from inktank comment this? Might be using /dev/ram0 with an >>>>>> fs on it be better than tmpfs as we can use dio? >>>>>> >>>>>> Greets, >>>>>> Stefan >>>>>> >>>>>>> ----- Mail original ----- >>>>>>> >>>>>>> De: "Stefan Priebe - Profihost AG" <[email protected]> >>>>>>> À: "Sébastien Han" <[email protected]> >>>>>>> Cc: "Mark Nelson" <[email protected]>, "Alexandre DERUMIER" >>>>>>> <[email protected]>, "ceph-devel" <[email protected]>, >>>>>>> "Mark Kampe" <[email protected]> >>>>>>> Envoyé: Jeudi 22 Novembre 2012 14:29:03 >>>>>>> Objet: Re: RBD fio Performance concerns >>>>>>> >>>>>>> Am 22.11.2012 14:22, schrieb Sébastien Han: >>>>>>>> And RAMDISK devices are too expensive. >>>>>>>> >>>>>>>> It would make sense in your infra, but yes they are really expensive. >>>>>>> >>>>>>> We need something like tmpfs - running in local memory but support >>>>>>> dio. >>>>>>> >>>>>>> Stefan >>> >>> -- To unsubscribe from this list: send the line "unsubscribe ceph-devel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
