Re: [Qemu-devel] [PATCH 9/9] block-migration: add named dirty bitmaps migration

[Paolo Bonzini]

On 12/01/2015 15:20, Vladimir Sementsov-Ogievskiy wrote:
> 
> On 09.01.2015 01:36, Paolo Bonzini wrote:
>> The bitmaps are transmitted many times in their entirety, but only the
>> last copy actually means something. The others are lost. This means
>> you should use the non-live interface (register_savevm). This will
>> simplify the code a lot.
> 
> But what if the dirty bitmap is really big?
> 
> For example, for 5 Pb drive the bitmap with granularity 65536 will be of
> 2 Gb size. So, shouldn't it be migrated iteratively for live migration?

But your code is not attempting to do that.  It is not attempting to
track the dirtiness of the dirty bitmap, so to speak.

For such a huge storage, in any case, I suspect the solution is to not
use QEMU's live operations and, instead, operate at the storage level.

Paolo