Date: Fri, 1 Apr 2011 18:20:13 +0200 (CEST) From: Oliver Fromme <olli@lurza.secnetix.de> To: freebsd-geom@FreeBSD.ORG Subject: gmirror question Message-ID: <201104011620.p31GKDbM036600@lurza.secnetix.de>
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Hi, I just logged into a machine when my zsh shell died before even printing the prompt. The machine runs with a gmirror of two disks (ad0 and ad1). ad1 has always been a little flaky, throwing errors every few weeks or months, then being disconnected by gmirror. This never caused any problems in the past; the machine just continued running with ad0 alone. A reboot always brought ad1 back, and after syncing gmirror, everything continued running fine for some weeks or months. However, when the same thing happened today, gmirror wasn't able to reroute all requests to ad0, it seems. That's why my shell died. I would like to understand *why* this could happen. I thought that it's the purpose of gmirror to keep everything running when one disk dies. This is what the kernel logged during the event: 17:50:42 ad1: TIMEOUT - READ_DMA retrying (1 retry left) LBA=778951 17:50:53 ad1: TIMEOUT - READ_DMA retrying (1 retry left) LBA=778215 17:51:36 unknown: TIMEOUT - READ_DMA retrying (1 retry left) LBA=777767 17:51:36 ata3: timeout waiting to issue command 17:51:36 ata3: error issuing READ_DMA command 17:51:36 GEOM_MIRROR: Request failed (error=6). ad1[WRITE(offset=155136, length=16384)] 17:51:36 GEOM_MIRROR: Device gm0: provider ad1 disconnected. 17:51:36 g_vfs_done():mirror/gm0s1a[READ(offset=398176256, length=45056)]error = 5 17:51:36 vnode_pager_getpages: I/O read error 17:51:36 vm_fault: pager read error, pid 78331 (zsh) 17:51:36 pid 78331 (zsh), uid 1000: exited on signal 11 (core dumped) In particular, I wonder about the third line which mentions an "unknown" device. I assume this comes from ad1 while it is being disconnected. Can anybody explain why the I/O error on gm0s1a happened? If it matters, this is a single-core machine (not SMP) running FreeBSD running 8-stable csupped on 2010-10-22. Best regards Oliver -- Oliver Fromme, secnetix GmbH & Co. KG, Marktplatz 29, 85567 Grafing b. M. Handelsregister: Registergericht Muenchen, HRA 74606, Geschäftsfuehrung: secnetix Verwaltungsgesellsch. mbH, Handelsregister: Registergericht Mün- chen, HRB 125758, Geschäftsführer: Maik Bachmann, Olaf Erb, Ralf Gebhart FreeBSD-Dienstleistungen, -Produkte und mehr: http://www.secnetix.de/bsd C++: "an octopus made by nailing extra legs onto a dog" -- Steve Taylor, 1998
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