Date: Mon, 15 Jan 2018 16:54:09 +0100 From: Borja Marcos <borjam@sarenet.es> To: Borja Marcos <borjam@sarenet.es> Cc: freebsd-fs@freebsd.org Subject: Re: Academic exercise: trying to recover a corrupted pool Message-ID: <1DB0315C-D267-4571-864F-73D1B275111B@sarenet.es> In-Reply-To: <F6B823C4-313E-4AF2-B1F6-6AFE8E17458B@sarenet.es> References: <F6B823C4-313E-4AF2-B1F6-6AFE8E17458B@sarenet.es>
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> On 8 Jan 2018, at 15:25, Borja Marcos <borjam@sarenet.es> wrote:
>
>
> Hi,
>
> ONLY AS AN ACADEMIC EXERCISE, WARNING :)
>
> I have a broken ZFS pool and I’m wondering wether it should be readable. The pool was made with four
> apparently troublesome OCZ SSD drives pulled from other systems. They are connected to a LSI2008 adapter.
>
> The pool was created as a raidz2, so it’s supposed to survive the loss of two drives. It has lost two of them
> and I am unable to import it.
>
> I have lost no useful data, I was using it just for testing. Now it has become an interesting study subject though :)
>
> Any ideas? I have tried to recover even doing the “radical thing” (zdb -Z -AAA -e -p /dev poolname). No success.
Now this is interesting. I copied the two surviving drives to data files on another system using “dd”.
And I used mdconfig to create file backed ram disks.
mdconfig -a -f /pool/disk1
mdconfig -a -f /pool/disk2
Trying an import with
zpool import -R /mnt -N -m -f -F -X poolname
I got a panic.
Fatal trap 12: page fault while in kernel mode
cpuid = 1; apic id = 02
fault virtual address = 0x188
fault code = supervisor read data, page not present
instruction pointer = 0x20:0xffffffff81381901
stack pointer = 0x28:0xfffffe046bf2b250
frame pointer = 0x28:0xfffffe046bf2b270
code segment = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process = 0 (zio_read_intr_6_0)
trap number = 12
panic: page fault
cpuid = 1
KDB: stack backtrace:
#0 0xffffffff806e3c17 at kdb_backtrace+0x67
#1 0xffffffff806a0176 at vpanic+0x186
#2 0xffffffff8069ffe3 at panic+0x43
#3 0xffffffff809953bd at trap_fatal+0x34d
#4 0xffffffff80995419 at trap_pfault+0x49
#5 0xffffffff80994c6a at trap+0x29a
#6 0xffffffff80979bb1 at calltrap+0x8
#7 0xffffffff81380fba at vdev_queue_io_to_issue+0x23a
#8 0xffffffff81380d33 at vdev_queue_io+0x103
#9 0xffffffff813a3bbc at zio_vdev_io_start+0x24c
#10 0xffffffff813a05bc at zio_execute+0xac
#11 0xffffffff8139ff0b at zio_nowait+0xcb
#12 0xffffffff8138205c at vdev_raidz_io_start+0x48c
#13 0xffffffff813a3c1d at zio_vdev_io_start+0x2ad
#14 0xffffffff813a05bc at zio_execute+0xac
#15 0xffffffff8139ff0b at zio_nowait+0xcb
#16 0xffffffff813802f1 at vdev_mirror_io_done+0x1f1
#17 0xffffffff813a3f58 at zio_vdev_io_done+0x1c8
Uptime: 27d3h5m23s
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