multipath usage

[Gabi Neculai]

Hello,

   I have compiled Esos 1.3.4 with lpfc (for Emulex initiator support) as a module, but I can't figure out how to use the multipath. I have activated "rc.multipathd_enable=YES" in rc.conf but "multipath -ll" shows nothing. All drives are present twice for every FC switch, the wwn appears in "/dev/disk/by-id/wwn-*", but there is no dm* device. Also I don't know how I can pass the configuration options to multipath in esos and what to use for getuid_callout.

   To keep the story short, below is my previous setup:

  I have some disk shelfs from a HP EVA, each with 14 FC drives. I have been using all with a Dell R710 (storage) server with:

- 4 x Emulex Zephyr-X 2Gb FC cards

- 2 x Qlogic ISP2432 4Gb FC cards

- Debian 9 and a custom compiled kernel 4.9.18 with scst support

  The disk shelfs are connected with 2 HP switches and with all Emulex cards (4 pieces x 2G = 8Gbps) and the 2 qla2432 cards (2 pieces x 4G = 8Gbps) are used as target for one host for now also with multipath support.

  There are a few soft raid devices over the multipathed disks which are presented as LUNs over the 2 qla2432 used as target cards.

  I can give more info if needed. Thank you.

[Marc Smith]

On Tue, Jan 23, 2018 at 6:07 AM, Gabi Neculai <gabi.n...@gmail.com> wrote:
> Hello,
>
> I have compiled Esos 1.3.4 with lpfc (for Emulex initiator support) as a
> module, but I can't figure out how to use the multipath. I have activated
> "rc.multipathd_enable=YES" in rc.conf but "multipath -ll" shows nothing. All
> drives are present twice for every FC switch, the wwn appears in
> "/dev/disk/by-id/wwn-*", but there is no dm* device. Also I don't know how I
> can pass the configuration options to multipath in esos and what to use for
> getuid_callout.

It should be the same as just about any other Linux distro... you'll
need to configure multipath.conf to your liking (namely whitelist your
devices as needed). We may use a slightly new version than RHEL for
example, and I believe getuid_callout has changed a bit over the years
-- check the documentation for version 0.7.3.

I'm not sure multipathd is needed to construct to table, but you
should probably start that too: /etc/rc.d/rc.multipathd start

>
> To keep the story short, below is my previous setup:
>
> I have some disk shelfs from a HP EVA, each with 14 FC drives. I have been
> using all with a Dell R710 (storage) server with:
> - 4 x Emulex Zephyr-X 2Gb FC cards
> - 2 x Qlogic ISP2432 4Gb FC cards
> - Debian 9 and a custom compiled kernel 4.9.18 with scst support
>
> The disk shelfs are connected with 2 HP switches and with all Emulex cards
> (4 pieces x 2G = 8Gbps) and the 2 qla2432 cards (2 pieces x 4G = 8Gbps) are
> used as target for one host for now also with multipath support.
> There are a few soft raid devices over the multipathed disks which are
> presented as LUNs over the 2 qla2432 used as target cards.
>
> I can give more info if needed. Thank you.

Commercial support for ESOS is available as well, if needed.

--Marc


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[Gabi Neculai]

Hello,

I don't have much experience with multipath and devmaper, but on Debian 9 just worked almost out of the box with only a few configuration touches (like use friendly names = no).

The getuid_callout for esos don't need to be defined, scsi_id is in /usr/local/lib/scsi_id and multipath get it by default correctly.

The multipathd daemon got started but all the maps are ignored, while the devices are not blacklisted. Some relevant portion of "multipath -v3 -ll" is below:

Jan 24 07:59:40 | 32000001862b1ae8b: assembled map [1 queue_if_no_path 0 1 1 service-time 0 2 1 65:176 1 8:240 1

]

Jan 24 07:59:40 | 32000001862b1ae8b: set ACT_CREATE (map does not exist)

Jan 24 07:59:40 | 32000001862b1ae8b: failed to load map, error 22

Jan 24 07:59:40 | 32000001862b1ae8b: domap (0) failure for create/reload map

Jan 24 07:59:40 | 32000001862b1ae8b: ignoring map

Using no firendly names, the map is the serial number of the drive, it's correctly build with all the paths but it is ignored. Leaving friendly names on it even creates the bindings file correctly, but the wwids is empty.

I hope I'll have more time later today to dig in to this... I'll post if I'll come up with a solution.

Thank you for your time.