Date: Fri, 14 Apr 2017 15:37:10 -0500 From: Larry Rosenman <ler@lerctr.org> To: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> Cc: Slawa Olhovchenkov <slw@zxy.spb.ru>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, Ngie Cooper <ngie@freebsd.org>, Alan Somers <asomers@freebsd.org> Subject: Re: svn commit: r316938 - head/sbin/savecore Message-ID: <A0AA951D-6F45-46E3-8B95-4254AA7899E6@lerctr.org> In-Reply-To: <EC89EB67-7854-4DE6-BD40-2626FF993181@gmail.com> References: <201704141941.v3EJfmCW003347@repo.freebsd.org> <CAOtMX2gPHWRGiE9UA5AevZz=cTv_qksAWX0H-xRjDEHp0huCVg@mail.gmail.com> <20170414201431.GF20974@zxy.spb.ru> <CEC6CDCF-2EF2-4CEF-BF54-91F3021EF262@gmail.com> <0CAE4B1C-228B-4C71-86E9-4337753DFF74@lerctr.org> <EC89EB67-7854-4DE6-BD40-2626FF993181@gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On 4/14/17, 3:33 PM, "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> wr=
ote:
=20
> On Apr 14, 2017, at 13:26, Larry Rosenman <ler@lerctr.org> wrote:
>=20
> On 4/14/17, 3:19 PM, "Ngie Cooper (yaneurabeya)" <owner-svn-src-all@f=
reebsd.org on behalf of yaneurabeya@gmail.com> wrote:
>=20
>> On Apr 14, 2017, at 13:14, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote=
:
>>=20
>> On Fri, Apr 14, 2017 at 01:49:51PM -0600, Alan Somers wrote:
>>=20
>>> On Fri, Apr 14, 2017 at 1:41 PM, Ngie Cooper <ngie@freebsd.org> wro=
te:
>>>> Author: ngie
>>>> Date: Fri Apr 14 19:41:48 2017
>>>> New Revision: 316938
>>>> URL: https://svnweb.freebsd.org/changeset/base/316938
>>>>=20
>>>> Log:
>>>> savecore: fix space calculation with respect to `minfree` in check=
_space(..)
>>>>=20
>>>> - Use strtoll(3) instead of atoi(3), because atoi(3) limits the
>>>> representable data to INT_MAX. Check the values received from
>>>> strtoll(3), trimming trailing whitespace off the end to maintain
>>>> POLA.
>>>> - Use `KiB` instead of `kB` when describing free space, total spac=
e,
>>>> etc. I am now fully aware of `KiB` being the IEC standard for 10=
24
>>>> bytes and `kB` being the IEC standard for 1000 bytes.
>>>> - Store available number of KiB in `available` so it can be more
>>>> easily queried and compared to ensure that there are enough KiB =
to
>>>> store the dump image on disk.
>>>> - Print out the reserved space on disk, per `minfree`, so end-user=
s
>>>> can troubleshoot why check_space(..) is reporting that there isn=
't
>>>> enough free space.
>>>>=20
>>>> MFC after: 7 weeks
>>>> Reviewed by: Anton Rang <rang@acm.com> (earlier diff), cem (earli=
er diff)
>>>> Tested with: positive/negative cases (see review); make tinderbox
>>>> Sponsored by: Dell EMC Isilon
>>>> Differential Revision: D10379
>>>=20
>>> The free space calculation is still uselessly conservative, because=
it
>>> doesn't account for the fact that core dumps will always be either
>>> spare or compressed. The result is that savecore will frequently
>>> refuse to save corefiles even when there's plenty of space. I
>>> proposed removing the space check altogether in
>>> https://reviews.freebsd.org/D2587. However, I agreed to wait until
>>> after the compressed core dump feature was merged, because then mos=
tly
>>> accurate space checks will be possible. AFAIK the compressed core
>>> dump feature still hasn't been finished.
>>=20
>> Is posible (in the future) to use multiple swaps (on multiple disks)
>> for save core dumps?
>=20
> Multiple swap devices is already handled by savecore(8), if one us=
es fstab(5) or dumpon(8). Otherwise, you must invoke savecore(8) on individu=
al devices.
>=20
> As far as saving to multiple disks is concerned, I would hope that=
one is using a redundancy capable filesystem (zfs) or RAID-like technology =
(gmirror, graid, LSI Fusion=E2=80=99s RAID product line) to stripe and/or mirror t=
he data across multiple disks.
=20
=E2=80=A6
=20
> How do I use multiple devices to have the system dump on all of my sw=
ap? I got a message about not enough space, but there (I think) was enough =
between multiple drives=E2=80=A6.
=20
Something like:
=20
- Create a zpool
- Mount zpool to /crashdumps
- Change dumpdir in /etc/rc.conf to be /crashdumps, e.g., echo =E2=80=98dumpd=
ir=3D/crashdumps=E2=80=99
=20
?
HTH,
-Ngie
=20
PS The issue with lack of space might be the issue that Alan brought up=
earlier with compressed dumps and overly conservative free space checks, or=
it might be the fact that dumpdir (default: /var/crash) is full.
I was talking about the actual crashdump to swap by the system. /var/crash=
has 10T of space (my root pool).
=20
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?A0AA951D-6F45-46E3-8B95-4254AA7899E6>