On Mon, Nov 13, 2017 at 08:37:37PM -0800, L A Walsh wrote:
> Karel Zak wrote:
> > On Sat, Nov 04, 2017 at 02:09:51AM -0700, L A Walsh wrote:
> > > I just tried blockdev on a HW raid device (/dev/sdb) composed of
> > > 4K disks that can (w/performance penalty) emulate 512 byte disk
> > > (i.e. have the 512e feature). It is returning 512.
> > >
> > > Any idea where this info should be showing up?
> >
> > Try
> >
> > --getiomin get minimum I/O size
> > --getioopt get optimal I/O size
> ----
>
> > sudo blockdev --getiomin /dev/sdb
> 512
> > sudo blockdev --getioopt /dev/sdb
> 0
> > or
> >
> > lsblk --topology
> -----
> (some lines deleted for brevity):
>
> NAME ALIGN IO:MIN OPT PHYSEC LOGSEC ROT SCHED RQSZ RA
> WSAME
> sda 0 512 0 512 512 1 bfq 256 512
> 0B
> └─sda1 0 512 0 512 512 1 bfq 256 512
> 0B
> └─Backup-Media 0 512 0 512 512 1 128 128
> 0B
> sdb 0 512 0 512 512 1 bfq 256 512
> 0B
> └─sdb1 0 512 0 512 512 1 bfq 256 512
> 0B
> ├─Data-Home 0 512 0 512 512 1 128 128
> 0B
> └─Data-Edge 0 512 0 512 512 1 128 128
> 0B
> sdc 0 512 0 512 512 1 bfq 256 512
> 0B
> ├─sdc1 0 512 0 512 512 1 bfq 256 512
> 0B
> └─sdc10 0 512 0 512 512 1 bfq 256 512
> 0B
>
> > It's possible that RAID (or another stacked device) uses 512
> > addressing, but for partitioning or mkfs-like tools we care about
> > minimal and optimal I/O.
> ----
> Nothing but the RAID controller seems to know about the 4096 physical
> size.
> (attached jpg from disk controller SW -- can see size under physical on
> right).
>
> If anything used a 512 byte offset anywhere, it would really impact
> performance, thus my concern about how or where a util would be able to read
> it...
Unfortunately userspace tools cannot play any usable role in this
story if your system (kernel) does not provide relevant information.
For mkfs and partitioning tools it's 512-bytes based devices...
Let's ask kernel developers.
Karel
--
Karel Zak <kzak@xxxxxxxxxx>
http://karelzak.blogspot.com
--
To unsubscribe from this list: send the line "unsubscribe util-linux" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
