Bug 24113

Summary: Newly added local disks cannot be formatted due to multipath
Product: Mageia Reporter: Frank Griffin <ftg>
Component: RPM PackagesAssignee: Kernel and Drivers maintainers <kernel>
Status: RESOLVED FIXED QA Contact:
Severity: major    
Priority: Normal CC: marja11
Version: Cauldron   
Target Milestone: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Source RPM: multipath-tools CVE:
Status comment:

Description Frank Griffin 2019-01-02 17:47:08 CET
I added a new hard drive to my existing cauldron system, and found that while I could delete and create partitions on it, I could not create an ext4 filesystem.  Formatting either with diskdrake or directly with mkfs.ext4 got the error:

/dev/sdc1 is apparently in use by the system; will not make a filesystem here!

Googling this turned up a lot of useless stuff blaming this on leftover RAID signatures, but I finally found the diagnosis in a RedHat post.  It appears that MGA makes any newly-detected disk eligible for multipath, and *that* constitutes being "in use by the system".

[root@ftgme2 dev]# multipath -ll               
Hitachi_HUA723030ALA640_MK0373YHJU4VVC dm-1 ATA,Hitachi HUA72303
size=2.7T features='0' hwhandler='0' wp=rw
`-+- policy='service-time 0' prio=1 status=active
  `- 3:0:0:0 sdc 8:32 active ready running

The RedHat suggestion was to put the following into /etc/multipath.conf (we ship an empty file):

blacklist {
        devnode "^sd[a-z]"
}

which prevents multipath processing for sd* disks.  Doing this followed by

[root@ftgme2 dev]# systemctl restart multipathd
[root@ftgme2 dev]# multipath -ll
[root@ftgme2 dev]#

worked, and I was able to format sdc1.

I am totally unfamiliar with RAID and multipath, so I don't know what the recommendation should be for MGA, but the current state of affairs is going to drive people nuts.  Nobody who adds a disk to a system is going to expect formaat to fail with a cryptic message, and it took me a day and a half of researching to find this diagnosis.

We should either ship the above blacklist or else improve on it.
[
Comment 1 Marja Van Waes 2019-01-02 21:24:59 CET
Assigning to the Kernel & Drivers maintainers, because multipath-tools belongs to the "System/Kernel and hardware" group.

CC: (none) => marja11
Source RPM: multipath => multipath-tools
Assignee: bugsquad => kernel

Comment 2 Frank Griffin 2020-01-18 05:15:16 CET
Closing, as /etc/multipath.conf no longer seems to exist.  multipath-tools is still installed, and there is a man page for multipath.conf, but we no longer ship an empty file, and I haven't seen the error again.

Status: NEW => RESOLVED
Resolution: (none) => FIXED