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.
