[dm-devel] [PATCH 22/30] multipath: Implement 'property' blacklist

Hannes Reinecke hare at suse.de
Fri Nov 7 09:09:58 UTC 2014

On 11/07/2014 10:04 AM, Bart Van Assche wrote:
> On 08/21/14 21:31, Hannes Reinecke wrote:
>> On 08/21/2014 06:37 PM, Bart Van Assche wrote:
>>> Hannes Reinecke <hare <at> suse.de> writes:
>>>> Multipath can only handle device properly which support the VPD
>>>> page 0x83. Originally this was ensured by 'scsi_id', which would
>>>> not present an ID_SERIAL value in these cases.
>>>> With the move to udev 'ID_SERIAL' is now always present, so
>>>> multipath would try to attach to _all_ SCSI devices.
>>>> This patch implements an 'property' blacklist, which allows to
>>>> blacklist a device based on the existence of udev properties.
>>>> Any device not providing the udev property from the whitelist
>>>> will be ignored.
>>>> The default whitelist is set to '(ID_WWN|ID_SCSI_VPD)'.
>>>> [ ... ]
>>> (replying to an e-mail of one year ago)
>>> Hello Hannes,
>>> I have a question about this patch. Which software component should
>>> set the
>>> ID_SCSI_VPD parameter ? Is it udev, now integrated in systemd ? I'm
>>> asking
>>> this because I haven't found any patch in the udev nor in the
>>> systemd
>>> repositories that sets the ID_SCSI_VPD parameter. Does this mean
>>> that
>>> another parameter should be used to restore support for SCSI
>>> devices that
>>> support the VPD page 0x83 but do not report a WWN in that page ?
>>> Or does
>>> this mean that systemd should be modified such that it sets the
>>> ID_SCSI_VPD parameter ?
>> That's actually simple typo. ID_SCSI_VPD was generated by one of the
>> earlier instances of the sg3_utils udev rules.
>> It should read 'SCSI_IDENT_LUN', as this is what the current udev
>> rules
>> from sg3_utils generate.
>> I have a patch queued in my sles12 patchset; but so far haven't found
>> time to clean them up and send upstream.
>> Will be doing so once sles12 is done...
> (replying to an e-mail of two months ago)
> Hello Hannes,
> Have you already been able to free up some time to revisit what has
> been discussed above ?
Not yet. I actually have avoided this issue, as multipath support
with systemd is a _really_ convoluted mess.
Plus there is an odd latency increase when doing a reconfiguration
(a 'resume' device-mapper ioctl can take up to 0.5 seconds !) which
I first need to chase down.
I've already sent a patch for this, but it only covers the
initial configuration; still need to have a look into the
reconfiguration stuff.

But yeah, I need to got through the patches and work on sending
them upstream.

In the meantime my patches can be found as usual under



Dr. Hannes Reinecke		      zSeries & Storage
hare at suse.de			      +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 21284 (AG Nürnberg)

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