>>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. ----- Mail original ----- De: "Stefan Priebe - Profihost AG" <s.pri...@profihost.ag> À: "Mark Nelson" <mark.nel...@inktank.com> Cc: "Alexandre DERUMIER" <aderum...@odiso.com>, "ceph-devel" <ceph-devel@vger.kernel.org>, "Mark Kampe" <mark.ka...@inktank.com>, "Sébastien Han" <han.sebast...@gmail.com> 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" <s.pri...@profihost.ag> >>>>> À: "Sébastien Han" <han.sebast...@gmail.com> >>>>> Cc: "Mark Nelson" <mark.nel...@inktank.com>, "Alexandre DERUMIER" >>>>> <aderum...@odiso.com>, "ceph-devel" <ceph-devel@vger.kernel.org>, >>>>> "Mark Kampe" <mark.ka...@inktank.com> >>>>> 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
