Re: [Xen-devel] Xen and 4K Sectors (was blkback and bcache)

[James Harper <james.harper@xxxxxxxxxxxxxxxx>]

> 
> I'm curious as to how you came to the conclusion that qemu always presents
> 512 byte sectors?

I checked the code. I could be wrong but the value 512 seemed pretty much 
hardcoded.

> When using bcache formatted to a 4k sector size, Windows Server 2008 just
> flat out refuses to install...
> This is true regardless of whether I'm passing an LV directly to the DomU
> (phy), or whether I'm using tap::aio or file.
> 
> When formatting the bcache to 512 byte size, Windows tries to install. I say
> "tries" as then my system kernel panics and reboots, but that's a bcache
> issue (I've posted the trace to the bcache list).
> 

I'm watching your thread on bcache list too.

Ideally, we'd be able to emulate 512e so windows can know that the underlying 
block size is 4k and will (in win7 and newer) align to that boundary where 
possible.

lvm seems pretty flexible wrt block size. I had my lvm with a pv with 4k block 
size and wanted 512 byte block size, so I split my raid, created a new raid 
with the now spare disk and created bcache with 512 byte block size, added the 
512 byte pv to the lvm (which is now 2 pv's one 512, one 4k), pvmove'd 
everything across, then removed the 4k pv and joined it to the new raid.
 
James

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel