Re: multipath-tools: symlinks and block devices in /dev/mapper

Re: multipath-tools: symlinks and block devices in /dev/mapper

[Xose Vazquez Perez]

Sean Stewart wrote:

> I've seen a couple of cases on distros that use system (RHEL7 and SLES12) where after the
> system boots, if you go to /dev/mapper, you will see the mpath entries are a mix of symlinks
> to the respective /dev/dm- device, and others are a block device.

It was reported to SuSE time ago, and it was fixed recently.
I did not see this bug in CentOS_7 1503+updates.

multipath-tools: symlinks and block devices in /dev/mapper

[Stewart, Sean]

Hi all,

I've seen a couple of cases on distros that use system (RHEL7 and SLES12) where after the
system boots, if you go to /dev/mapper, you will see the mpath entries are a mix of symlinks
to the respective /dev/dm- device, and others are a block device.

After some investigation, it looks like the symlink is created by udev, and the block device
file gets created with the call to dm_lib_exit(), from the multipath command. Of course, if
one has already created its device file, the other can't.

So I'm wondering why do we have both mechanism to create /dev/mapper/ links and files? It
doesn't really hurt anything, but I think it's strange that it's not consistent.

Thoughts?


Thanks,

Sean Stewart
Linux Software Engineer
Hyperscale Storage Group
NetApp