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On Tue, Dec 3, 2013 at 5:22 PM, Jc García <jyo.garcia@×××××.com> wrote: |
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> 2013/12/3 Canek Peláez Valdés <caneko@×××××.com>: |
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>> On Tue, Dec 3, 2013 at 12:06 AM, Canek Peláez Valdés <caneko@×××××.com> wrote: |
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>>> On Mon, Dec 2, 2013 at 10:34 PM, Jc García <jyo.garcia@×××××.com> wrote: |
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>>>> 2013/12/2 William Kenworthy <billk@×××××××××.au> |
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>>>>> |
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>>>>> You are looking far too deep .... |
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>>>>> |
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>>>>> |
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>>>>> just rsync -avP to /newusr |
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>>>> |
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>>>> +1 |
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>>>> I have done this more or less the same way |
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>>>>> |
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>>>>> reboot to livecd |
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>>>>> |
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>>>>> rsync again with --delete to update ... takes a only few seconds this |
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>>>>> time - minimal downtime :) |
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>>>>> mv /usr /oldusr |
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>>>>> mv /newusr /usr |
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>>>>> reboot |
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>>>> |
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>>>> |
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>>>> Let's make this thread more interesting, would it be possible to do |
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>>>> this without a reboot? ie: going single user mode, kill anything that |
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>>>> might still be running from usr, umount /usr, mount it to /mnt, rsync |
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>>>> -avP to usr, going again into runlevel 3 or 5. |
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>>>> Obviously not possible if running systemd. |
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>>> |
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>>> I'm not so sure it's not possible. Perhaps it's even easier. |
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>> |
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>> So, yeah, I think it's easier with systemd. You just: |
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>> |
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>> 1. systemctl isolate emergency.target |
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>> 2. log in again (all the normal gettys are killed with the above command) |
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>> 3. rsync -PvasHA /usr/ /newusr/ |
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>> 4. mv /usr /oldusr # mv is on /bin, so no problems here |
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>> 5. mv /newusr /usr |
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>> 6. rm -rf /oldusr (to make sure nothing uses it anymore) |
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>> 7. systemctl isolate multi-user.target |
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>> 8. You have your system again. |
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>> |
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> Nice, I thought systemd residing within /usr would be the limitation, |
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> i haven't used systemd very much , so i don't really know it's options, |
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> but later after thinking about it, i thought that using the initramfs |
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> would be a way to go, |
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> but as i understand here systemd already has an option to make use of it. |
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Yeah, you can create an initramfs with dracut that uses systemd; the |
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initramfs mounts /usr, and then handles back control to the systemd |
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instance in it. When shutting down, the inverse occurs; the systemd in |
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/usr handles back control to the systemd in the initramfs, which in |
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turns shutdowns the machine. |
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I don't know exactly how problematic would be for a complex setup |
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(/usr using LVM+cryptfs+mdraid, for example), but if the necessary |
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tools are available in the initramfs, then I think it could be done. |
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Of course, the simplest and easiest thing to do is to use a live CD. |
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Regards. |
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-- |
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Canek Peláez Valdés |
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Posgrado en Ciencia e Ingeniería de la Computación |
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Universidad Nacional Autónoma de México |
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