Date: Tue, 4 Feb 2014 21:36:15 -0800 From: aurfalien <aurfalien@gmail.com> To: Graham Allan <allan@physics.umn.edu> Cc: FreeBSD FS <freebsd-fs@freebsd.org> Subject: Re: practical maximum number of drives Message-ID: <7D20F45E-24BC-4595-833E-4276B4CDC2E3@gmail.com> In-Reply-To: <52F1BDA4.6090504@physics.umn.edu> References: <52F1BDA4.6090504@physics.umn.edu>
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Hi Graham, When you say behaved better with 1 HBA, what were the issues that made = you go that route? Also, curious that you have that many drives on 1 PCI card, is it PCI 3 = etc=85 and is saturation an issue? - aurf On Feb 4, 2014, at 8:27 PM, Graham Allan <allan@physics.umn.edu> wrote: > 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"
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