@George: George Moutsopoulos (gmoutso) wrote on 2015-04-29: > OK, I managed! I had to add more modules > > sudo echo "dm_cache" >> /etc/initramfs-tools/modules > sudo echo "dm_cache_mq" >> /etc/initramfs-tools/modules > sudo echo "dm_persistent_data" >> /etc/initramfs-tools/modules > sudo echo "dm_bufio" >> /etc/initramfs-tools/module --- Not exactly related to the original bug, but wanted to address a boo-boo in the above. sudo echo "string" won't use root's access/permissions to write to the files when using the shell-redirection operators '>' or '>>'. sudo will execute 'echo' with root privs, and that will echo "dm_cache" (et al.), however, that output is redirected by the *SHELL* (running as "whoever is running the shell") -- usually the user.
To get around this problem (and not saying there might not be any easier ways, as this seemed a bit roundabout to get what I wanted (have root write the output to "wherever"), I used "dd", as in: echo "dm_cache"|sudo dd of=destination status=none or to append: echo "dm_cache"|sudo dd status=none oflag=append conv=notrunc of=/etc /initramfs-tools/modules or to do all at once: (echo dm_cache echo dm_cache_mq echo dm_persistent_data echo dm_bufio)|sudo dd status=none oflag=append conv=notrunc of=/initramfs-tools/modules I wanted to write a single "char" to a file in /proc/sys/vm (drop_caches). Perhaps needless to say, I put it in a script file to save on typing. :-) -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lvm2 in Ubuntu. https://bugs.launchpad.net/bugs/1423796 Title: Unable to mount lvmcache root device at boot time Status in initramfs-tools package in Ubuntu: Confirmed Status in linux package in Ubuntu: Confirmed Status in lvm2 package in Ubuntu: Confirmed Bug description: I'm experimenting with Vivid Vervet on a virtual machine and tried a new LVM feature, lvmcache. I made a cache for the root file system, rebuilt the initrd and rebooted the VM. At boot time, the system failed to activate the root LV. After some investigation, I found out, it's because the initrd is missing some essential stuff needed for activating a cached LV. The initrd was missing the dm-cache module. I regenerated the initrd with explicitly listing dm-cache in /etc/initramfs-tools/modules, but the system still can't boot up, because now it is missing the /usr/sbin/cache_check utility. As SSDs are becoming more and more common, I think it will be common to use them as cache for root file systems, thus it is mandatory to make sure that an initrd can mount an lvmcached root device when necessary, preferably without /etc/initramfs-tools/modules and other manual initrd hacking. System details: Linux lvmvm 3.18.0-13-generic #14-Ubuntu SMP Fri Feb 6 09:55:14 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux Distributor ID: Ubuntu Description: Ubuntu Vivid Vervet (development branch) Release: 15.04 Codename: vivid LVM version: 2.02.111(2) (2014-09-01) Library version: 1.02.90 (2014-09-01) Driver version: 4.28.0 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/initramfs-tools/+bug/1423796/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : email@example.com Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp