Missing SAS phy enumeration in newer versions of udev path_id
Hi,
We recently upgraded our version of udev and I saw that the symlinks under /dev/disk/by-path/ have changed since udev started using the path_id C code to no longer include phy enumeration for SAS disks. Was this change intentional? Would anyone mind if i re-create the behavior of the old bash script as we were using it?
Best Regards,
Nils Carlson
Quoted 8 lines · Nils Carlson
Hi,
We recently upgraded our version of udev and I saw that the symlinks under
/dev/disk/by-path/have changed since udev started using thepath_idC code to no longer include phy enumeration for SAS disks. Was this change intentional? Would anyone mind if i re-create the behavior of the old bash script as we were using it?
Not everybody at once ... I've just had several customer calls for exactly the same issue.
Actually ... the company name seems to be vaguely familiar ...
To quote myself:
Quoted 6 lines
Problem is that SAS has something called 'wide-ports', ie inherent port-bonding for SAS. When a system has wide ports, several PHYs are merged _physically_ together into a single connector. However, on the system side we're only seeing PHYs, so it' impossible to tell which of the phy has been used.
Quoted 7 lines
So to handle this correctly we would need to generate symlinks for each phy in a wide port; however, currently the
path_idprogram is only capable of printing out _one_ link per wide port.And actually, the original
path_idscript also printed out only one symlink, so even there it didn't handle wide ports correctly.
I've discussed this issue with Kay Sievers, and we agreed that we should be fixing this.
It should be relatively easy to update the path_id program to print out a link for each phy in a wide-port, and then we could do a static enumeration via udev rules like
$env{ID_SAS_PHY0}="?*", SYMLINK+="/dev/disk/by-path/$ID_SAS_PHY0" $env{ID_SAS_PHY1}="?*", SYMLINK+="/dev/disk/by-path/$ID_SAS_PHY1"
seeing that there is currently a max of 8 phys per wide port, we only would need to specify 8 lines here. Which should be too bad.
You're welcome to lend a hand ...
Cheers,
Hannes
Signature · 4 lines
Dr. Hannes Reinecke zSeries & Storage [email protected] +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)