On 11-08-12 09:28 AM, joystick wrote:

Hi all IDE and SCSI ml's,

is it guaranteed by the standards that reading from a device a region that has
been TRIMmed (IDE) or UNMAPped (SCSI) will certainly return zeroes?

ATA:
In 'hdparm -I' you need to see this line:
    *  Deterministic read ZEROs after TRIM
[See the ATA IDENTIFY DEVICE command]

SCSI:
In the READ CAPACITY (16) response the LBPRZ needs to
be set to 1. Recently the same LBPRZ bit was added to
the Logical Block Provisioning VPD page (sbc3r27.pdf).

Doug Gilbert