[Bug 1641078] Re: System cannot be booted up when root filesystem is on an LVM on two disks

[Marcin Janowski]

Edit, i havent upgrade jet ubuntu 18.04 to 20.04, so i dont know if this
work on upgraded.

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Title:
  System cannot be booted up when root filesystem is on an LVM on two
  disks

Status in Ubuntu on IBM z Systems:
  Invalid
Status in s390-tools package in Ubuntu:
  Invalid

Bug description:
  ---Problem Description---
  LVMed root file system acrossing multiple disks cannot be booted up 
    
  ---uname output---
  Linux ntc170 4.4.0-38-generic #57-Ubuntu SMP Tue Sep 6 15:47:15 UTC 2016 s390x s390x s390x GNU/Linux
   
  ---Patches Installed---
  n/a
   
  Machine Type = z13 
   
  ---System Hang---
   cannot boot up the system after shutdown or reboot
   
  ---Debugger---
  A debugger is not configured
   
  ---Steps to Reproduce---
   Created root file system on an LVM and the LVM crosses two disks. After shut down or reboot the system, the system cannot be up. 
   
  Stack trace output:
   no
   
  Oops output:
   no
   
  System Dump Info:
    The system is not configured to capture a system dump.
   
  Device driver error code:
   Begin: Mounting root file system ... Begin: Running /scripts/local-top ...   lvmetad is not active yet, using direct activation during sysinit 
    Couldn't find device with uuid 7PC3sg-i5Dc-iSqq-AvU1-XYv2-M90B-M0kO8V. 
   
  -Attach sysctl -a output output to the bug.

  More detailed installation description:

  The installation was on a FCP SCSI SAN volumes each with two active
  paths.  Multipath was involved.  The system IPLed fine up to the point
  that we expanded the /root filesystem to span volumes.  At boot time,
  the system was unable to locate the second segment of the /root
  filesystem.   The error message indicated this was due to lvmetad not
  being not active.

  Error message:   
         Begin: Running /scripts/local-block ...   lvmetad is not active yet, using direct activation during sysinit 
         Couldn't find device with uuid 7PC3sg-i5Dc-iSqq-AvU1-XYv2-M90B-M0kO8V 
          Failed to find logical volume "ub01-vg/root" 
          
  PV Volume information: 
  physical_volumes { 

                 pv0 { 
                         id = "L2qixM-SKkF-rQsp-ddao-gagl-LwKV-7Bw1Dz" 
                         device = "/dev/sdb5"        # Hint only 

                         status = ["ALLOCATABLE"] 
                         flags = [] 
                         dev_size = 208713728        # 99.5225 Gigabytes 
                         pe_start = 2048 
                         pe_count = 25477        # 99.5195 Gigabytes 
                 } 

                 pv1 { 
                         id = "7PC3sg-i5Dc-iSqq-AvU1-XYv2-M90B-M0kO8V" 
                         device = "/dev/sda"        # Hint only 

                         status = ["ALLOCATABLE"] 
                         flags = [] 
                         dev_size = 209715200        # 100 Gigabytes 
                         pe_start = 2048 
                         pe_count = 25599        # 99.9961 Gigabytes 

  
  LV Volume Information: 
  logical_volumes { 

                 root { 
                         id = "qWuZeJ-Libv-DrEs-9b1a-p0QF-2Fj0-qgGsL8" 
                         status = ["READ", "WRITE", "VISIBLE"] 
                         flags = [] 
                         creation_host = "ub01" 
                         creation_time = 1477515033        # 2016-10-26 16:50:33 -0400 
                         segment_count = 2 

                         segment1 { 
                                 start_extent = 0 
                                 extent_count = 921        # 3.59766 Gigabytes 

                                 type = "striped" 
                                 stripe_count = 1        # linear 

                                 stripes = [ 
                                         "pv0", 0 
                                 ] 
                         } 
                         segment2 { 
                                 start_extent = 921 
                                 extent_count = 25344        # 99 Gigabytes 

                                 type = "striped" 
                                 stripe_count = 1        # linear 

                                 stripes = [ 
                                         "pv1", 0 
                                 ] 
                         } 
                 } 

  
  Additional testing has been done with CKD volumes and we see the same behavior.   Only the UUID of the fist volume in the VG can be located at boot, and the same message:  lvmetad is not active yet, using direct activation during sysinit 
  Couldn't find device with uuid xxxxxxxxxxxxxxxxx  is displayed for CKD disks. Just a different UUID is listed.   
  If the file /root file system only has one segment on the first volume,  CKD or SCSI  volumes, the system will IPL.  Because of this behavior, I do not believe the problem is related to SAN disk or multipath.   I think it is due to the system not being able to read the UUID on any PV in the VG other then the IPL disk.

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