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

[Stefan G. Weichinger]

Am 12.09.18 um 15:07 schrieb J. Roeleveld:

> 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)

thanks for the links etc

To me it seems that the former administrator somehow tried to set that 
up but failed.

This corresponds to something he wrote when leaving the company.

There is no multipathd-daemon enabled or running.

# multipath
Sep 14 08:31:10 | MSA2040_SAMBA_storage: ignoring map
Sep 14 08:31:10 | MSA2040_SAMBA_storage: ignoring map

# multipath -l
#

# ls /dev/mapper/
control


so nothing gets mapped here ;-)

-

# /etc/multipath.conf

defaults {
#  udev_dir                /dev
   polling_interval        15
#  selector                "round-robin 0"
   path_grouping_policy    group_by_prio
   failback                5
   path_checker            tur
#  prio_callout            "/sbin/mpath_prio_tpc /dev/%n"
   rr_min_io               100
   rr_weight               uniform
   no_path_retry           queue
   user_friendly_names     yes
}
blacklist {
   devnode cciss
   devnode fd
   devnode hd
   devnode md
   devnode sr
   devnode scd
   devnode st
   devnode ram
   devnode raw
   devnode loop
   devnode sda
   devnode sdb
}

multipaths {
   multipath {
     wwid  3600c0ff0001e91b2c1bae25601000000
     ## To find your wwid, please use /usr/bin/sg_vpd --page=di /dev/DEVICE.
     ## The address will be a 0x6. Remove the 0x and replace it with 3.
     alias MSA2040_SAMBA_storage
   }
}


--- I will check docs etc asap
That is a productive server a few 100 kms away from me, so I have to be 
careful.

Users can work, so no hurry here, just interest.