From: L A Walsh <lkml@tlinx.org>
To: Karel Zak <kzak@redhat.com>
Cc: util-linux@vger.kernel.org
Subject: Re: what should blockdev getbpsz return 4k disks w/512e?
Date: Mon, 13 Nov 2017 20:37:37 -0800 [thread overview]
Message-ID: <5A0A7311.8040007@tlinx.org> (raw)
In-Reply-To: <20171106101938.a6l6t3r37qtqtuks@ws.net.home>
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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...
[-- Attachment #2: disk_sizes1.jpg --]
[-- Type: image/jpeg, Size: 175005 bytes --]
next prev parent reply other threads:[~2017-11-14 4:37 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-04 9:09 what should blockdev getbpsz return 4k disks w/512e? L A Walsh
2017-11-06 10:19 ` Karel Zak
2017-11-14 4:37 ` L A Walsh [this message]
2017-11-14 10:08 ` Karel Zak
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