Date: Fri, 14 Apr 2017 15:43:34 -0500 From: Larry Rosenman <ler@lerctr.org> To: "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com> Cc: "src-committers@freebsd.org" <src-committers@freebsd.org>, Alan Somers <asomers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, Slawa Olhovchenkov <slw@zxy.spb.ru>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, Ngie Cooper <ngie@freebsd.org> Subject: Re: svn commit: r316938 - head/sbin/savecore Message-ID: <AB41FBB8-12D6-48D7-BE34-664D2F267A2F@lerctr.org> In-Reply-To: <12820BAB-D8BA-4EDE-89BC-4BDB56B1E57A@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> <A0AA951D-6F45-46E3-8B95-4254AA7899E6@lerctr.org> <12820BAB-D8BA-4EDE-89BC-4BDB56B1E57A@gmail.com>
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On 4/14/17, 3:39 PM, "Ngie Cooper (yaneurabeya)" <owner-svn-src-all@freebsd=
.org on behalf of yaneurabeya@gmail.com> wrote:
=20
> On Apr 14, 2017, at 13:37, Larry Rosenman <ler@lerctr.org> wrote:
>=20
> On 4/14/17, 3:33 PM, "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.c=
om> wrote:
>=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@=
freebsd.org on behalf of yaneurabeya@gmail.com> wrote:
>>=20
>>> On Apr 14, 2017, at 13:14, Slawa Olhovchenkov <slw@zxy.spb.ru> wrot=
e:
>>>=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> wr=
ote:
>>>>> 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 chec=
k_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 spa=
ce,
>>>>> 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-use=
rs
>>>>> 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 (earl=
ier diff)
>>>>> Tested with: positive/negative cases (see review); make tinderbo=
x
>>>>> Sponsored by: Dell EMC Isilon
>>>>> Differential Revision: D10379
>>>>=20
>>>> The free space calculation is still uselessly conservative, becaus=
e 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 unti=
l
>>>> after the compressed core dump feature was merged, because then mo=
stly
>>>> 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 s=
wap? 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=98=
dumpdir=3D/crashdumps=E2=80=99
>=20
> ?
> HTH,
> -Ngie
>=20
> PS The issue with lack of space might be the issue that Alan broug=
ht up earlier with compressed dumps and overly conservative free space check=
s, or it might be the fact that dumpdir (default: /var/crash) is full.
>=20
>=20
> I was talking about the actual crashdump to swap by the system. /var=
/crash has 10T of space (my root pool).
=20
If your memory is bigger than your swap, you=E2=80=99re unfortunately not abl=
e to save the mini dump if the size of the saved pages exceed the space on s=
wap. I think this is where markj=E2=80=99s compressed dumps feature will come in h=
andy.
Thanks!
-Ngie
Yeah, I have the following:
borg.lerctr.org /home/ler $ swapctl -l
Device: 1024-blocks Used:
/dev/mfid0p3 8388608 0
/dev/mfid1p3 8388608 0
/dev/mfid2p3 8388608 0
/dev/mfid3p3 8388608 0
/dev/mfid4p3 8388608 0
/dev/mfid5p3 8388608 0
borg.lerctr.org /home/ler $ sysctl hw.physmem
hw.physmem: 137368682496
borg.lerctr.org /home/ler $
SO 6 8G partitions (48G), but the dump is larger than 8G.=20
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