Date: Tue, 12 Dec 2006 13:47:49 +0100 From: "Julian H. Stacey" <jhs@flat.berklix.net> To: "Pascal Hofstee" <caelian@gmail.com> Cc: FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: umass intermittently "stalling" ... processes seemingly stuck in "wdrain" state Message-ID: <200612121247.kBCClnAG002515@fire.jhs.private> In-Reply-To: <d8a0b7620612120254p44a96f63gcfa06debc3f73e82@mail.gmail.com> References: <d8a0b7620612120254p44a96f63gcfa06debc3f73e82@mail.gmail.com>
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"Pascal Hofstee" wrote: > I recently bought an USB Mass Storage unit (about 300GB) and a 4+1 > slot PCI USB2.0 card (since it's an old box that didn't have USB 2 on > board yet), and i have noticed that intermittently the device "stalls" > any operations that try to access it: > > - copying data onto the disk > - reading data from the disk > - running an ls while inside a directory on the disk's mount point > > Today while trying to scp a fairly large set of files from my office > system to my umass disk at home i noticed the similar stalling > behaviour and decided to check ps output on my home system. There i > noticed that every single time to scp session would begin stalling > (lasting up to about 30-40s per stall) ... the scp process on my > home-system would have dropped into a wdrain state. > > As soon as the scp process (after about 30 or more seconds) would > finally get out of this wdrain state (usually into an sbwait state) > the scp process on my work system would start picking up transfer > speed again until the next slip into wdrain. > > I haven't been able to test this on a non-CURRENT system yet so i am > not sure wether or not this is a CURRENT only issue or a more generic > problem, but if somebody could give some pointers on where to start > looking on fixing this ... i am open for suggestions. I've seen stalling on 1 of 2 x 6.1-RELEASE hosts. I was given an 80 Gig external USB (Freecom) (disc reported to be unstable on XP, but as I don't run XP ... :-). I ran disc for a long time OK via a Zediworks USB2 powered hub, to a Belkin USB2 Cardbus on my laptop with 6.1-RELEASE. No recent problems (OK, various USB2 devices on laptop used to cause crashes, (that didnt crash on the inbuilt USB-1), I assumed it was because Belkin overheating - card got too hot to touch in middle ! (My brother reckons his Belkin may have died in my laptop under FreeBSD, his identical laptop didnt kill his Belkin under XP - my guess was maybe FreeBSD wasn't switching Belkin card into idle state to keep it cool ? but that's another issue)). Moved 80G drive to a direct connection on main 6.1-RELEASE tower. Persistent hangs. umount -f would eventually work, then I did fsck & mount, & repeated. I didnt observe ps states. Moved disc back to laptop, no hangs. I'd assumed hardware problem & thought next to try moving hub too. Now I've read your post I'll look at PS states too. (My 80G drive is a 3.5" with own power supply, not a laptop drive in external unpowered box needing more than the 0.5A delivered by a USB connection.) -- Julian Stacey. BSD Unix C Net Consultancy, Munich/Muenchen http://berklix.com Mail Ascii, not HTML. Ihr Rauch = mein allergischer Kopfschmerz. http://berklix.org/free-software
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