[dm-crypt] Alignment issue with 4K disk

Yves-Alexis Perez corsac at debian.org
Tue Jan 5 11:14:02 CET 2016


On mar., 2016-01-05 at 00:02 +0100, Sven Eschenberg wrote:
> Hi Alexis,

(Yves-Alexis actually)
> 
> I stumbled over this line:
> 
> I/O size (minimum/optimal): 4096 bytes / 33553920 bytes
> 
> The latter resembles 65535 sectors (512 Byte logical ones), which 
> explains why the automated alignment was done at sector 65535. This 
> value seems extremely weird though.
> 
> You said the drive was external, connected how? USB maybe?

Yes. It's a Samsung T3 disk, so everything is integrated (disk+sata/usb3
adapter), not much chance I can do anything here.

I'll try to force the alignment to 2048s for part1 and see what happens.
> 
> Can you take a look at hdparm -I /dev/sdc? Anything unusual there?

I'll try tonight (I don't have it at hand).

Thanks for the pointers though.
-- 
Yves-Alexis

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