HAMMER filesystem check / CRC verification

[Matthew Dillon]

Older versions of HAMMER could cause some 'B'ad flags in the show output
due to the mirror_tid not being updated up the chain properly.  This should
have been fixed a few years ago.

-Matt

On Fri, Jan 22, 2016 at 11:01 AM, PeerCorps Trust Fund <
ipc at peercorpstrust.org> wrote:

> Thank you. These are quite useful.
>
> On 01/22/2016 05:57 PM, Tomohiro Kusumi wrote:
> > If you are to redirect the hammer show output to a file, it's better to
> > write to a file on different filesystem (e.g. ufs or another hammer).
> >
> > It's possible that hammer show never ends because what hammer show does
> is
> > run through all ondisk btree nodes. Writing a file is adding nodes into
> the
> > btree of that filesystem.
> >
> >
> > 2016-01-23 0:44 GMT+09:00 Tomohiro Kusumi <kusumi.tomohiro at gmail.com>:
> >
> >> (resending as i forgot to send to users at ...)
> >>
> >> # hammer -v -f ${DEV} blockmap
> >> # hammer -v -f ${DEV} checkmap
> >> # hammer -v -f ${DEV} show
> >>
> >> These three do some validation from different point of view.
> >> If the last two lines of each output says 0 error, then no error was
> found
> >> at least by what these 3 commands test for.
> >>
> >> Note that there seems to be a bug in hammer where a valid filesystem
> would
> >> still show ^B in hammer show output. I usually run some test scripts
> (that
> >> contain there 3 commands) before I commit something, but I see ^B in
> hammer
> >> show every once in a while. It could be that the way hammer show tests
> the
> >> filesystem is missing something and results in showing errors that
> aren't
> >> really errors. This occurred at least back in DragonFly 4.0 era in 2014,
> >> and it still does on 4.4. It has been on my todo list for a long time.
> >>
> >>
> >> 2016-01-22 23:59 GMT+09:00 PeerCorps Trust Fund <ipc at peercorpstrust.org
> >:
> >>
> >>> Hi All,
> >>>
> >>> In ZFS, the command "zpool status" gives a succinct overview of the
> >>> status of mounted file systems. In particular, whether there might be
> >>> checksum errors on files or other data structures.
> >>>
> >>>         NAME        STATE     READ WRITE CKSUM
> >>>         tank        ONLINE       0     0     0
> >>>           ada0p2    ONLINE       0     0     0
> >>>
> >>> In HAMMER the "show" command provides an extremely detailed output of
> all
> >>> data structures and CRC verifications.
> >>>
> >>> I've used the command:
> >>>
> >>> hammer -f /dev/serno/disk-serial-number show |grep B------
> >>>
> >>> On a mounted disk and the output was clean (nothing) after running for
> >>> some time with noted disk activity. Does this mean that all CRCs are
> valid?
> >>> Are there other commands in addition to "show" that allow for
> validation
> >>> and examination of data structures on HAMMER volumes?
> >>>
>
> Mike
>
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