[Bug 1441930] Re: Fix handling of multipathed disks with 4k-sectors

[Mauricio Faria de Oliveira]

Description updated w/ QEMU/KVM command line for 4k-sector disks.
It reproduces this bug and the fix.

	[    0.221249] scsi 0:0:1:0: Direct-Access     QEMU     QEMU HARDDISK    2.1. PQ: 0 ANSI: 5
	[    0.221382] scsi 0:0:2:0: Direct-Access     QEMU     QEMU HARDDISK    2.1. PQ: 0 ANSI: 5
	...
	[    0.254668] sd 0:0:1:0: [sda] 4194304 4096-byte logical blocks: (17.1 GB/16.0 GiB)
	...
	[    0.255837] sd 0:0:2:0: [sdb] 4194304 4096-byte logical blocks: (17.1 GB/16.0 GiB)
	
	~ # blockdev --getss /dev/sda
	4096
	~ # blockdev --getss /dev/sdb
	4096

	~ # cmp /sys/block/sd[ab]/device/vpd_pg83; echo $?
	0

** Description changed:

  The packages for libparted and kpartx don't have the patches for using
  multipath (actually device-mapper) on 4k-sector disks (generally: 'non
  512-byte sector disks')
  
  This causes the number of sectors of each device-mapper partition to be 1/8th (512/4096) of that expected.
  These 3 errors were identified:
  1) Partition sizes on multipath are 1/8th of the intended size
  2) The filesystem on the underlying device is not-accessible (only in the dm mapped device)
  3) grub-install fails w/ 'Unknown filesystem'
  
  The 2 patches attached contains upstream patches from parted and
  multipath-tools, and fix the issues (the installation finishes without
  errors and the system boots).
+ 
+ 
+ QEMU/KVM
+ --------
+ 
+ If you don't have 4k-sector disks handy :)
+ 
+ An example for multipath on 4k-sector disks, with 2 underlying devices:
+ 
+         $ qemu-img create -f raw disk.img 16g
+ 
+ 	$ qemu-system-ppc64 -enable-kvm \
+ 	  -nographic -nodefaults \
+ 	  -monitor stdio -serial pty \
+ 	  -M pseries -m 2G \
+ 	  -net nic -net user \
+ 	  -drive media=cdrom,file=../../iso/vivid-server-ppc64el.iso.0408 \
+ 	  \
+ 	  -drive file=disk.img,if=none,cache=none,serial=my-serial,id=drive0 \
+ 	  -drive file=disk.img,if=none,cache=none,serial=my-serial,id=drive1 \
+ 	  -device scsi-hd,physical_block_size=4096,logical_block_size=4096,drive=drive0 \
+ 	  -device scsi-hd,physical_block_size=4096,logical_block_size=4096,drive=drive1

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https://bugs.launchpad.net/bugs/1441930

Title:
  Fix handling of multipathed disks with 4k-sectors

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