zfs discuss - Dec 2011 - Any rhyme or reason to disk dev names?

Hello,

I am curious to know if there is an easy way to guess or identify the
device names of disks. Previously the /dev/dsk/c0t0d0s0 system made sense
to me... I had a SATA controller card with 8 ports, and they showed up with
the numbers 1-8 in the "t" position of the device name.

But I just built a new system with two LSI SAS HBAs in it, and my device
names are along the lines of:
/dev/dsk/c0t5000CCA228C0E488d0

I could not find any correlation between that identifier and the a)
controller the disk was plugged in to, or b) the port number on the
controller. The only way I could make a mapping of device name to
controller port was to add one drive at a time, reboot the system, and run
"format" to see which new disk name shows up.

I''m guessing there''s a better way, but I can''t find
any obvious answer as
to how to determine which port on my LSI controller card will correspond
with which seemingly random device name. Can anyone offer any suggestions
on a way to predict the device naming, or at least get the system to list
the disks after I insert one without rebooting?

Thank you!
-Matthew
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> I am curious to know if there is an easy way to guess or identify
> the device names of disks.
Have a look at the file /etc/path_to_inst.  There you will find all
device instances managed by a particular driver.  The first entry of
each line is the physical device.

If you then look in /dev/rdsk and check which symbolic link of the
form c<N>t<N>d<N>s<N> points to this physical device,
you have your match.

One caveat is that if you move disks around, /etc/path_to_inst will
grow, and there is no guarantee that any device listed in this file is
really present in the running system.


HTH -- Volker
-- 
------------------------------------------------------------------------
Volker A. Brandt               Consulting and Support for Oracle Solaris
Brandt & Brandt Computer GmbH                   WWW: http://www.bb-c.de/
Am Wiesenpfad 6, 53340 Meckenheim, GERMANY            Email: vab at bb-c.de
Handelsregister: Amtsgericht Bonn, HRB 10513              Schuhgr??e: 46
Gesch?ftsf?hrer: Rainer J.H. Brandt und Volker A. Brandt

"When logic and proportion have fallen sloppy dead"

On 2011-12-21 09:22, vab at bb-c.de wrote:
>> I am curious to know if there is an easy way to guess or identify
>> the device names of disks.
>
> Have a look at the file /etc/path_to_inst.  There you will find all
> device instances managed by a particular driver.  The first entry of
> each line is the physical device.
>
> If you then look in /dev/rdsk and check which symbolic link of the
> form c<N>t<N>d<N>s<N>  points to this physical
device, you have your match.
>
> One caveat is that if you move disks around, /etc/path_to_inst will
> grow, and there is no guarantee that any device listed in this file is
> really present in the running system.
>
>
> HTH -- Volker

Take a look at ''diskinfo'' - should be in Solaris 10U10 and
Solaris 11.


Cheers,
  Henrik

On 21/12/11 05:58 PM, Matthew R. Wilson wrote:
> Hello,
>
> I am curious to know if there is an easy way to guess or identify the
> device names of disks. Previously the /dev/dsk/c0t0d0s0 system made sense
> to me... I had a SATA controller card with 8 ports, and they showed up
> with the numbers 1-8 in the "t" position of the device name.
>
> But I just built a new system with two LSI SAS HBAs in it, and my device
> names are along the lines of:
> /dev/dsk/c0t5000CCA228C0E488d0
>
> I could not find any correlation between that identifier and the a)
> controller the disk was plugged in to, or b) the port number on the
> controller. The only way I could make a mapping of device name to
> controller port was to add one drive at a time, reboot the system, and run
> "format" to see which new disk name shows up.
>
> I''m guessing there''s a better way, but I can''t
find any obvious answer as
> to how to determine which port on my LSI controller card will correspond
> with which seemingly random device name. Can anyone offer any suggestions
> on a way to predict the device naming, or at least get the system to list
> the disks after I insert one without rebooting?
Hi Matthew,
By default the names for disks attached via mpt_sas(7d), or
mpt(7d) if your disks are new enough, is to use their WWN
as reported in the SCSI INQUIRY Page83 response.

The old paradigm you refer to is based on the physical id
of the device on a parallel SCSI bus. That doesn''t scale
with SAS, and is something we''re trying to move away from.

If you''d like some info about how we use devids and guids,
please refer to my presentation

http://www.jmcp.homeunix.com/~jmcp/WhatIsAGuid.pdf


For your particular configuration, if you note the serial
number and WWN of the device before you insert them, you
can match that up with info from  iostat -En  and/or prtconf -v.


hth,
James C. McPherson
--
Oracle
http://www.jmcp.homeunix.com/blog

On Wed, Dec 21, 2011 at 1:58 AM, Matthew R. Wilson
<mwilson at mattwilson.org> wrote:
> Hello,
>
> I am curious to know if there is an easy way to guess or identify the
device
> names of disks. Previously the /dev/dsk/c0t0d0s0 system made sense to me...
> I had a SATA controller card with 8 ports, and they showed up with the
> numbers 1-8 in the "t" position of the device name.
>
> But I just built a new system with two LSI SAS HBAs in it, and my device
> names are along the lines of:
> /dev/dsk/c0t5000CCA228C0E488d0
>
> I could not find any correlation between that identifier and the a)
> controller the disk was plugged in to, or b) the port number on the
> controller. The only way I could make a mapping of device name to
controller
> port was to add one drive at a time, reboot the system, and run
"format" to
> see which new disk name shows up.
>
> I''m guessing there''s a better way, but I can''t
find any obvious answer as to
> how to determine which port on my LSI controller card will correspond with
> which seemingly random device name. Can anyone offer any suggestions on a
> way to predict the device naming, or at least get the system to list the
> disks after I insert one without rebooting?
Depending on the hardware you are using, you may be able to benefit
from croinfo.

$ croinfo
D:devchassis-path                  t:occupant-type  c:occupant-compdev
---------------------------------  ---------------  ---------------------
/dev/chassis//SYS/SASBP/HDD0/disk  disk             c0t5000CCA012B66E90d0
/dev/chassis//SYS/SASBP/HDD1/disk  disk             c0t5000CCA012B68AC8d0

The text in the left column represents text that should be printed on
the corresponding disk slots.

-- 
Mike Gerdts
http://mgerdts.blogspot.com/

On Dec 21, 2011, at 2:58, "Matthew R. Wilson" <mwilson at
mattwilson.org> wrote:
> Can anyone offer any suggestions on a way to predict the device naming, or
at least get the system to list the disks after I insert one without rebooting?
You have gotten some good responses that should help you out.

However, you shouldn''t have to reboot to see the new disks try
devfsadm.

On Dec 21, 2011, at 3:14 AM, James C. McPherson wrote:
> On 21/12/11 05:58 PM, Matthew R. Wilson wrote:
>> Hello,
>> 
>> I am curious to know if there is an easy way to guess or identify the
>> device names of disks. Previously the /dev/dsk/c0t0d0s0 system made
sense
>> to me... I had a SATA controller card with 8 ports, and they showed up
>> with the numbers 1-8 in the "t" position of the device name.
>> 
>> But I just built a new system with two LSI SAS HBAs in it, and my
device
>> names are along the lines of:
>> /dev/dsk/c0t5000CCA228C0E488d0
>> 
>> I could not find any correlation between that identifier and the a)
>> controller the disk was plugged in to, or b) the port number on the
>> controller. The only way I could make a mapping of device name to
>> controller port was to add one drive at a time, reboot the system, and
run
>> "format" to see which new disk name shows up.
>> 
>> I''m guessing there''s a better way, but I
can''t find any obvious answer as
>> to how to determine which port on my LSI controller card will
correspond
>> with which seemingly random device name. Can anyone offer any
suggestions
>> on a way to predict the device naming, or at least get the system to
list
>> the disks after I insert one without rebooting?
> 
> Hi Matthew,
> By default the names for disks attached via mpt_sas(7d), or
> mpt(7d) if your disks are new enough, is to use their WWN
> as reported in the SCSI INQUIRY Page83 response.
> 
> The old paradigm you refer to is based on the physical id
> of the device on a parallel SCSI bus. That doesn''t scale
> with SAS, and is something we''re trying to move away from.
More to the point, on SAS and other similar busses, there simply
*isn''t* such a thing as a simple target number.  The old numbering
scheme from parallel SCSI was suitable when you could have only 7 or 15 or so
devices on a single bus.  With modern busses you can have many thousands of
devices on the same fabric.  So we address them by WWN.

	- Garrett
> 
> If you''d like some info about how we use devids and guids,
> please refer to my presentation
> 
> http://www.jmcp.homeunix.com/~jmcp/WhatIsAGuid.pdf
> 
> 
> For your particular configuration, if you note the serial
> number and WWN of the device before you insert them, you
> can match that up with info from  iostat -En  and/or prtconf -v.
> 
> 
> hth,
> James C. McPherson
> --
> Oracle
> http://www.jmcp.homeunix.com/blog
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss

Thank you for all of the good pointers, everyone. croinfo and diskinfo
don''t give me any output, but that''s not surprising since this
is a
home-built system. But it''s good to know those utilities exist for
production hardware.

Making the association between the disk serial number and target number by
matching them up in the iostat -En or prtconf output looks like it will
work for me.

Thanks again!

-Matthew

On Wed, Dec 21, 2011 at 8:21 AM, Garrett D''Amore <Garrett.DAmore at
nexenta.com
> wrote:
>
> On Dec 21, 2011, at 3:14 AM, James C. McPherson wrote:
>
> > On 21/12/11 05:58 PM, Matthew R. Wilson wrote:
> >> Hello,
> >>
> >> I am curious to know if there is an easy way to guess or identify
the
> >> device names of disks. Previously the /dev/dsk/c0t0d0s0 system
made
> sense
> >> to me... I had a SATA controller card with 8 ports, and they
showed up
> >> with the numbers 1-8 in the "t" position of the device
name.
> >>
> >> But I just built a new system with two LSI SAS HBAs in it, and my
device
> >> names are along the lines of:
> >> /dev/dsk/c0t5000CCA228C0E488d0
> >>
> >> I could not find any correlation between that identifier and the
a)
> >> controller the disk was plugged in to, or b) the port number on
the
> >> controller. The only way I could make a mapping of device name to
> >> controller port was to add one drive at a time, reboot the system,
and
> run
> >> "format" to see which new disk name shows up.
> >>
> >> I''m guessing there''s a better way, but I
can''t find any obvious answer
> as
> >> to how to determine which port on my LSI controller card will
correspond
> >> with which seemingly random device name. Can anyone offer any
> suggestions
> >> on a way to predict the device naming, or at least get the system
to
> list
> >> the disks after I insert one without rebooting?
> >
> > Hi Matthew,
> > By default the names for disks attached via mpt_sas(7d), or
> > mpt(7d) if your disks are new enough, is to use their WWN
> > as reported in the SCSI INQUIRY Page83 response.
> >
> > The old paradigm you refer to is based on the physical id
> > of the device on a parallel SCSI bus. That doesn''t scale
> > with SAS, and is something we''re trying to move away from.
>
> More to the point, on SAS and other similar busses, there simply
*isn''t*
> such a thing as a simple target number.  The old numbering scheme from
> parallel SCSI was suitable when you could have only 7 or 15 or so devices
> on a single bus.  With modern busses you can have many thousands of devices
> on the same fabric.  So we address them by WWN.
>
>        - Garrett
> >
> > If you''d like some info about how we use devids and guids,
> > please refer to my presentation
> >
> > http://www.jmcp.homeunix.com/~jmcp/WhatIsAGuid.pdf
> >
> >
> > For your particular configuration, if you note the serial
> > number and WWN of the device before you insert them, you
> > can match that up with info from  iostat -En  and/or prtconf -v.
> >
> >
> > hth,
> > James C. McPherson
> > --
> > Oracle
> > http://www.jmcp.homeunix.com/blog
> > _______________________________________________
> > zfs-discuss mailing list
> > zfs-discuss at opensolaris.org
> > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
>
>
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Dear Matthew,

Some methods were not mentioned that have been discussed on zfs-discuss@
in the past several times. Useful for list archives at least:
. One easy way to detect disk locations is to make the lights blink if you
have lights per drive in your chassis. But it does not scale. For example
something similar to dd if=/dev/dsk/c0t5000CCA228C0E488d0 of=/dev/null
. Other methods have been discussed (check the archives), for example:
http://mail.opensolaris.org/pipermail/zfs-discuss/2011-June/048982.html
Quoting one example from above post by Richard:
> For the later Nexenta, OpenSolaris or Solaris 11 Express releases the
mpt_sas driver will try to light the
> OK2RM (ok to remove) LED for a disk when you use cfgadm to disconnect
the paths. Apparently this also
> works for SATA disks in an enclosure that manages SATA disks. The
process is documented very nicely
> by Cindy in the ZFS Admin Guide. However, there are a number of
enclosures that do not have an OK2RM
> LED. YMMV.
If you got other good pointers off-list, may I suggest to make a summary
for the list as this question pops up often.


Regards,

Ville


From: zfs-discuss-bounces at opensolaris.org
[mailto:zfs-discuss-bounces at opensolaris.org] On Behalf Of Matthew R.
Wilson
Sent: Thursday, December 22, 2011 1:39 AM
To: zfs-discuss at opensolaris.org
Subject: Re: [zfs-discuss] Any rhyme or reason to disk dev names?

Thank you for all of the good pointers, everyone. croinfo and diskinfo
don''t give me any output, but that''s not surprising since this
is a
home-built system. But it''s good to know those utilities exist for
production hardware.

Making the association between the disk serial number and target number by
matching them up in the iostat -En or prtconf output looks like it will
work for me.

Thanks again!

-Matthew
On Wed, Dec 21, 2011 at 8:21 AM, Garrett D''Amore
<Garrett.DAmore at nexenta.com> wrote:

On Dec 21, 2011, at 3:14 AM, James C. McPherson wrote:
> On 21/12/11 05:58 PM, Matthew R. Wilson wrote:
>> Hello,
>>
>> I am curious to know if there is an easy way to guess or identify the
>> device names of disks. Previously the /dev/dsk/c0t0d0s0 system made
sense
>> to me... I had a SATA controller card with 8 ports, and they showed up
>> with the numbers 1-8 in the "t" position of the device name.
>>
>> But I just built a new system with two LSI SAS HBAs in it, and my
device
>> names are along the lines of:
>> /dev/dsk/c0t5000CCA228C0E488d0
>>
>> I could not find any correlation between that identifier and the a)
>> controller the disk was plugged in to, or b) the port number on the
>> controller. The only way I could make a mapping of device name to
>> controller port was to add one drive at a time, reboot the system, and
run
>> "format" to see which new disk name shows up.
>>
>> I''m guessing there''s a better way, but I
can''t find any obvious answer
as
>> to how to determine which port on my LSI controller card will
correspond
>> with which seemingly random device name. Can anyone offer any
suggestions
>> on a way to predict the device naming, or at least get the system to
list
>> the disks after I insert one without rebooting?
>
> Hi Matthew,
> By default the names for disks attached via mpt_sas(7d), or
> mpt(7d) if your disks are new enough, is to use their WWN
> as reported in the SCSI INQUIRY Page83 response.
>
> The old paradigm you refer to is based on the physical id
> of the device on a parallel SCSI bus. That doesn''t scale
> with SAS, and is something we''re trying to move away from.
More to the point, on SAS and other similar busses, there simply
*isn''t*
such a thing as a simple target number. ?The old numbering scheme from
parallel SCSI was suitable when you could have only 7 or 15 or so devices
on a single bus. ?With modern busses you can have many thousands of
devices on the same fabric. ?So we address them by WWN.

? ? ? ?- Garrett
>
> If you''d like some info about how we use devids and guids,
> please refer to my presentation
>
> http://www.jmcp.homeunix.com/~jmcp/WhatIsAGuid.pdf
>
>
> For your particular configuration, if you note the serial
> number and WWN of the device before you insert them, you
> can match that up with info from ?iostat -En ?and/or prtconf -v.
>
>
> hth,
> James C. McPherson
> --
> Oracle
> http://www.jmcp.homeunix.com/blog
> _______________________________________________
> zfs-discuss mailing list
> zfs-discuss at opensolaris.org
> http://mail.opensolaris.org/mailman/listinfo/zfs-discuss