On Mon, Sep 26, 2016 at 09:25:11AM -0700, Christoph Hellwig wrote: > On Mon, Sep 26, 2016 at 12:19:26PM -0400, Theodore Ts'o wrote: > > Is this a problem with the hardware, or with the UAS driver? > > UAS is just SCSI transport, and doesn't touch the content of command, > so it's a very unlikely culprit. The SCSI layer intreprets it, but I > don't really think it's doing any of this either.. Your bridge most > likely always reports 4k sectors when using UAS for some reason. > > To verify this call sg_readcap on the device node for both the > usb-storage and uas mode. sg_readcap doesn't report the physical sector size, just the logical block size: # sg_readcap /dev/sdd Read Capacity results: Last logical block address=4000797359 (0xee7752af), Number of blocks=4000797360 Logical block length=512 bytes Hence: Device size: 2048408248320 bytes, 1953514.3 MiB, 2048.41 GB And this is the same for both with and with UAS. So with UAS we get: # blockdev --getpbsz /dev/sdd 4096 ...even though hdparm -I reports: Logical Sector size: 512 bytes Physical Sector size: 512 bytes I guess this is mostly cosmetic, since although lsblk -t reports: # lsblk -t NAME ALIGNMENT MIN-IO OPT-IO PHY-SEC LOG-SEC ROTA SCHED RQ-SIZE RA WSAME sdd 0 4096 33553920 4096 512 1 cfq 128 128 32M ├─sdd2 0 4096 33553920 4096 512 1 cfq 128 128 32M │ └─callcc_crypt -1 4096 0 4096 512 1 128 128 0B nothing is actually _breaking_ since the logical sector size is still 512, and the minimum I/O and physical sector size are performance hints. - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
