Date: Wed, 5 Feb 2014 10:42:45 -0800 From: aurfalien <aurfalien@gmail.com> To: Daniel Kalchev <daniel@digsys.bg> Cc: freebsd-fs <freebsd-fs@freebsd.org> Subject: Re: practical maximum number of drives Message-ID: <785DBF11-1550-4918-B346-4843D7E2AF0B@gmail.com> In-Reply-To: <52F1FBBA.1000909@digsys.bg> References: <52F1BDA4.6090504@physics.umn.edu> <7D20F45E-24BC-4595-833E-4276B4CDC2E3@gmail.com> <52F1DEBC.9020304@digsys.bg> <CAOeNLuqhT1y7rzA2=80jzXByrYy0cbCTaFv-5=X1KOnkFtRN8Q@mail.gmail.com> <52F1FBBA.1000909@digsys.bg>
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Cool. But I was more curious about what lead you to using 1 HBA over using a = few more. You mentioned something about interrupts, what problems manifested as a = result of multi HBAs? - aurf On Feb 5, 2014, at 12:52 AM, Daniel Kalchev <daniel@digsys.bg> wrote: > Ok, two things. >=20 > First, it was a typo -- the number is 122 devices and I actually got = it from the likes of this FAQ entry: = http://www.supermicro.com/support/faqs/faq.cfm?faq=3D10004 > I never use these for anything other than HBA. >=20 > It is interesting to see that LSI claims 3000 devices. Might be, = firmware has changed? Or there are different variations of the = chip/implementation? >=20 > Daniel >=20 > On 05.02.14 10:08, Rich wrote: >> The SAS2008 has a limit of 112 drives? >>=20 >> = http://www.lsi.com/downloads/Public/SAS%20ICs/LSISAS2008/SCG_LSISAS2008_PB= _043009.pdf >> claims "up to 3000 devices." >>=20 >> SAS2008 is a PCIe gen 2 x8 chip. >>=20 >> I suspect the bottleneck order would go SAS expander then SAS2008 = then PCIe. >>=20 >> - Rich >>=20 >> On Wed, Feb 5, 2014 at 1:48 AM, Daniel Kalchev <daniel@digsys.bg> = wrote: >>> I also wonder how you managed to go over the LSI2008's limit of 112 >>> drives... >>>=20 >>>=20 >>> On 05.02.14 07:36, aurfalien wrote: >>>> Hi Graham, >>>>=20 >>>> When you say behaved better with 1 HBA, what were the issues that = made you >>>> go that route? >>>>=20 >>>> Also, curious that you have that many drives on 1 PCI card, is it = PCI 3 >>>> etc... and is saturation an issue? >>>>=20 >>>> - aurf >>>>=20 >>>> On Feb 4, 2014, at 8:27 PM, Graham Allan <allan@physics.umn.edu> = wrote: >>>>=20 >>>>> This may well be a question with no real answer but since we're = speccing >>>>> out a new ZFS-based storage system, I've been asked what the = maximum number >>>>> of drives it can support would be (for a hypothetical expansion = option). >>>>> While there are some obvious limits such as SAS addressing, I = assume there >>>>> must be more fundamental ones in the kernel or drivers, and the = practical >>>>> limits will be very different from the hypothetical ones. >>>>>=20 >>>>> So far the largest system we've built is using three 45-drive = chassis on >>>>> one SAS2008 (mps) controller, so 135 drives total. Over many = months of >>>>> running we had several drives fail and be replaced, and eventually = the OS >>>>> (9.1) failed to assign new da devices. It was time to patch the = system and >>>>> reboot anyway, which solved it, but we did wonder if we were = running into >>>>> some kind of limit around 150 drives - though I don't see why. >>>>>=20 >>>>> Interestingly we initially built this system with each drive = chassis on >>>>> its own SAS2008 HBA, but it ultimately behaved better = daisy-chained with >>>>> only one. I think I saw a hint somewhere this could be to do with = interrupt >>>>> sharing... >>>>>=20 >>>>> Thanks for any insights, >>>>>=20 >>>>> Graham >>>>> _______________________________________________ >>>>> freebsd-fs@freebsd.org mailing list >>>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >>>>> To unsubscribe, send any mail to = "freebsd-fs-unsubscribe@freebsd.org" >>>> _______________________________________________ >>>> freebsd-fs@freebsd.org mailing list >>>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >>>> To unsubscribe, send any mail to = "freebsd-fs-unsubscribe@freebsd.org" >>>=20 >>>=20 >>> _______________________________________________ >>> freebsd-fs@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-fs >>> To unsubscribe, send any mail to = "freebsd-fs-unsubscribe@freebsd.org" >=20 > _______________________________________________ > freebsd-fs@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-fs > To unsubscribe, send any mail to "freebsd-fs-unsubscribe@freebsd.org"
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