Date: Mon, 27 Jun 2005 21:40:08 +0800 From: Xin LI <delphij@frontfree.net> To: Skylar Thompson <skylar@cs.earlham.edu> Cc: fs@freebsd.org Subject: Re: Snapshot problems Message-ID: <20050627134008.GA5764@frontfree.net> In-Reply-To: <20050626182031.GA5268@quark.cs.earlham.edu> References: <20050626182031.GA5268@quark.cs.earlham.edu>
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[-- Attachment #1 --] On Sun, Jun 26, 2005 at 01:20:31PM -0500, Skylar Thompson wrote: > I've discovered a repeatable problem with FreeBSD's UFS2 snapshots. If I > create several snapshots, and then do heavy disk I/O on the original > filesystem (deletions, creations, simple touches, etc.) I can cause the I/O > system to crash. There is no kernel panic, and the machine still answers > pings, but no disk I/O occurs. I can replicate this on a dual-processor > beige-box system with a Mylex RAID controller and a RAID-5 set, and also on > a dual-processor Dell Poweredge 2650 with a PERC 3/i RAID controller and a > RAID-5 set and RAID-1 set. FreeBSD 5.4-RELEASE is installed on both > systems, and SMP is enabled as well, with HTT disabled on the Poweredge. I > have DDB compiled in, so I can get debug information but I don't know what > to look for. I think a script that can reliably trigger the "crash" would be helpful. What do you mean by "IO system crash", BTW? I got confused since it does not cause kernel panic and stop ping responses. Do you mean that the I/O system was stalled/suspended when there is heavy disk operations? My guess is that there is some underlying deadlock(s) present. Would you mind compiling WITESS/WITESS_SUPPORT into your kernel and give it a try? This will reduce performance, but would also be helpful for picking locking bugs. Thanks in advance! Cheers, -- Xin LI <delphij frontfree net> http://www.delphij.net/ See complete headers for GPG key and other information. [-- Attachment #2 --] -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.1 (FreeBSD) iD8DBQFCwAG4/cVsHxFZiIoRAsDvAKCIIHcGqSx3btWHVgfqE2s9HmMNFACfYRdh TTmCWZEvoMVYBK1buCScNDY= =Iqkn -----END PGP SIGNATURE-----help
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