Re: [gentoo-user] Rebuilding a kernel on a hardened gentoo

[J. Roeleveld]

On Wednesday, September 12, 2018 2:14:05 PM CEST J. Roeleveld wrote:
> On September 12, 2018 7:43:12 AM UTC, "Stefan G. Weichinger"
<lists@×××××.at> wrote:
> >Am 12.09.18 um 08:42 schrieb J. Roeleveld:
> >> On Tuesday, September 11, 2018 11:48:59 AM CEST Stefan G. Weichinger
> >
> >wrote:
> >>> At first I emerged latest stable gentoo-sources, enabled these flags
> >
> >and
> >
> >>> compiled ... but the lpfc module didn't detect the SAN devices
> >>> correctly, so I switched back to 4.1.15 (mark this as another todo
> >
> >here
> >
> >>> ... sooner or later I want a more recent kernel working with lpfc
> >
> >... I
> >
> >>> have no clue about multipath so far)
> >>
> >> I found multipath quite "simple" to implement when following the
> >
> >documentation
> >
> >> for this.
> >
> >*which* documentation, please?
> >
> >with the newer kernel I got:
> >
> >[  864.521464] lpfc 0000:02:00.1: 1:1303 Link Up Event x7b received
> >Data: x7b x0 x20 x0 x0 x0 0
> >[  868.693743] lpfc 0000:02:00.0: 0:1305 Link Down Event x7c received
> >Data: x7c x20 x80011 x0 x0
> >[  869.523664] lpfc 0000:02:00.0: 0:1303 Link Up Event x7d received
> >Data: x7d x0 x20 x0 x0 x0 0
> >[  873.691535] lpfc 0000:02:00.1: 1:1305 Link Down Event x7c received
> >Data: x7c x20 x80011 x0 x0
> >[  874.521185] lpfc 0000:02:00.1: 1:1303 Link Up Event x7d received
> >Data: x7d x0 x20 x0 x0 x0 0
> >[  878.694259] lpfc 0000:02:00.0: 0:1305 Link Down Event x7e received
> >Data: x7e x20 x80011 x0 x0
> >
> >
> >and no /dev/sdX created for the relevant LUN (is that the term?)
> >
> >I see a multipath.conf on the system, will try to understand that.
>
> Multipath devices end up under /dev/mapper/...
>
> I think it was Redhat who had most decent docs. Will check my bookmarks
> tonight and give you the full list.

Bit sooner:
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/
dm_multipath/mpio_overview

https://www.thegeekdiary.com/beginners-guide-to-device-mapper-dm-multipathing/


I use multipath from a SAS-controller to a dual-backplane and SAS-disks.
From the controller, I have 2 paths to each disk, which means I have twice the 
amount of "sd?" entries.

==
# multipath -l
35000cca25d8ec910 dm-4 HGST,HUS726040ALS210
size=3.6T features='1 retain_attached_hw_handler' hwhandler='0' wp=rw
|-+- policy='service-time 0' prio=0 status=active
| `- 0:0:7:0  sdh 8:112  active undef running
`-+- policy='service-time 0' prio=0 status=enabled
  `- 0:0:20:0 sdt 65:48  active undef running
==
(This is only the first device)

It shows that device "35000cca25d8ec910" is mapped to "sdh" and "sdt".
To use the disk correctly, I need to access "/dev/mapper/35000cca25d8ec910", 
which is:
# ls -lsa /dev/mapper/35000cca25d8ec910
0 lrwxrwxrwx 1 root root 7 Sep  4 11:43 /dev/mapper/35000cca25d8ec910 -> ../
dm-4

I have "multipathd" in the "boot" runlevel.

Version info:
# eix -I multipath
[I] sys-fs/multipath-tools
     Available versions:  0.5.0-r1 0.6.4-r1{tbz2} ~0.7.6^t ~0.7.7^t {rbd 
systemd KERNEL="linux"}
     Installed versions:  0.6.4-r1{tbz2}(10:51:01 AM 01/23/2018)(-rbd -
systemd)
     Homepage:            http://christophe.varoqui.free.fr/
     Description:         Device mapper target autoconfig

# uname -a
Linux san1 4.9.76-gentoo-r1-generic #1 SMP Tue Jan 23 12:05:11 CET 2018 x86_64 
Intel(R) Xeon(R) CPU E5-2620 v4 @ 2.10GHz GenuineIntel GNU/Linux

As for the terms, a LUN is a Logical disk provided by a SAN to a different 
system. I have multipath inside my SAN and have a single path to iSCSI 
clients. (Single switch with bonded NICs)

--
Joost