Kernel Live Patch...

From: Dennis Ullrich
Date: Fri May 08 2015 - 14:04:45 EST


Dear all,

I want to make a proposal which is similar to online kernel patching without reboot... The idea is to do something which could work similar to the live kernel patching method. I don't know how difficult it would be, to implement my proposal, but here it comes.

For example I have a HDD with one partiton and a Oracle DB on the ext4 filesystem. I want to migrate it live to another storage (for example a LPFC LUN via Multipath) with all processes etc. on the FS.
My idea is to modify the IOStack that it is able to make a "bitwise" copy and "simply" move the Filesystem to its new place on a blockdevice.
The point is, to have control about the copy-progress and tell the IOStack which device is to use for the requested data, on every access. When the copy is done, the admin should be able to remove the old drive. All processes should be on the new blockdevice after the movement.

What do you think about this idea?


Best regards,
Dennis

P.S. I know that there are solutions (md, lvm) to do this, if its configured in the first place. But you will need a downtime for the final switch between new and old (because of the processes).
But in this case I really mean a function which is independent from any partiton table, filesystem etc.
and works only on blockdevices.
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