[LP: #1491148] growpart doesn't work with mdraid devices

[paride]

Originally reported by: Mario Villaplana on 2015-09-01
Original bug URL: https://bugs.launchpad.net/cloud-utils/+bug/1491148
Last Launchpad Status: Triaged
Last Launchpad Importance: Medium

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I was attempting to run growpart when booting off of a RAID device and noticed that growpart never grows the root partition properly.

During boot, I get the message:

GROWROOT: FAILED: /dev/md126p: does not exist

I then modified the "growroot" wrapper that gets put into the initramfs that takes the root partition and finds the name of the root disk from it. It looks like that script simply takes the root partition and strips the last consecutive numbers to find the root disk. For example:

/dev/sda1 -> /dev/sda
/dev/md126p1 -> /dev/md126p

/dev/md126p doesn't exist because the RAID disk name is /dev/md126.

I changed it so that the script always uses /dev/md126 as the disk with 2 variations: one that uses "1" as the partition number, and one that uses "p1" as the partition number. The former fails because "/dev/md1261 does not exist", and the latter fails because the growpart script checks to see that the partition number is actually a numerical value.

This can probably be fixed by modifying growpart to allow the use of numerical values prefixed by "p" for partition numbers and modifying the growroot script that gets put in the initramfs to properly do string formatting with mdraid device names.

Thanks for your time.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: cloud-utils 0.25-0ubuntu5.1
Uname: Linux 4.0.3 x86_64
NonfreeKernelModules: ext4 crc16 mbcache jbd2 raid1 md_mod mousedev hid_generic usbhid hid sd_mod coretemp x86_pkg_temp_thermal kvm_intel kvm ahci crc32c_intel libahci aesni_intel iTCO_wdt aes_x86_64 glue_helper squashfs libata iTCO_vendor_support i2c_i801 ehci_pci lpc_ich xhci_pci sb_edac lrw ixgbe gf128mul ipmi_ssif ablk_helper hwmon xhci_hcd ptp ehci_hcd loop cryptd edac_core usbcore microcode firmware_class scsi_mod tpm_tis pps_core i2c_core mfd_core usb_common mdio tpm ipmi_si ipmi_msghandler evdev button sch_fq_codel autofs4
ApportVersion: 2.0.1-0ubuntu17.9
Architecture: amd64
Date: Tue Sep 1 20:45:44 2015
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm-256color
 PATH=(custom, no user)
 SHELL=/bin/bash
SourcePackage: cloud-utils
UpgradeStatus: No upgrade log present (probably fresh install)

Related bugs:
bug 1799953: growpart does not work for lvm