SCSI device names

JoeBre at exabyte.com JoeBre at exabyte.com
Wed Oct 23 15:31:14 PDT 2002


* From the T10 Reflector (t10 at t10.org), posted by:
* JoeBre at exabyte.com
*
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I would like to see all protocols employing a consistant name format.
The ability of a device to have a name that differs per protocol has
been a headache for some time. In fact, I would tend to claim that a
name with such a property is not a name at all, but rather some weaker
degenerate identifier.

Rob's suggestion has merit, as it seems to provide a clear path from the
current confusion to a situation wherein a name is a deterministic,
uniquely identifying attribute of the named object.

Joe Breher 
Exabyte Corp 

> -----Original Message----- 
> From: Elliott, Robert (Server Storage) [ mailto:Elliott at hp.com
 ] 
> Sent: Wednesday, October 23, 2002 9:24 AM 
> To: George Penokie 
> Cc: t10 
> Subject: RE: SCSI device names 
> 
> 
> * From the T10 Reflector (t10 at t10.org), posted by: 
> * "Elliott, Robert (Server Storage)" <Elliott at hp.com> 
> * 
> A SAS-only device would still base its device name off an NAA 
> identifier.  It would just be expressed as 
> "naa.5WWWXXXXYYYYZZZZ" rather 
> than as an 8 byte binary value. 
> 
> We can mandate that those identifiers still share the NAA 
> namespace (as 
> "eui." would share the EUI-64 namespace). 
> 
> What it helps solve is a device that has both ports using different 
> transport protocols, where two or more device names would be needed 
> under current rules.  This is a big complication for 
> software. Since the 
> string format is capable of expressing all 3 in use today - "iqn." 
> "eui." and "naa." - it seems like the best candidate. 
> 
> This problem also affects the logical unit name (association 0h).  A 
> native SAS or FC device will want to use an NAA format; an InfiniBand 
> SRP device will want to use an EUI-64 format; an iSCSI device 
> will want 
> to use an "iqn." based format.  If the target device has target ports 
> with all those protocols, how does it choose?  I think the only answer

> is "any of them it wants." 
> 
> -- 
> Rob Elliott, elliott at hp.com 
> Industry Standard Server Storage Advanced Technology 
> Hewlett-Packard 
> 
> 
> 
> > -----Original Message----- 
> > From: George Penokie [ mailto:gop at us.ibm.com 
] 
> > Sent: Wednesday, October 23, 2002 10:03 AM 
> > To: Elliott, Robert (Server Storage) 
> > Cc: t10 
> > Subject: Re: SCSI device names 
> > 
> > 
> > 
> > 
> > 
> > 
> > Rob, 
> > My first reaction was 'are you crazy'!  My second reaction 
> > was 'we maybe that would be a good idea'. But after thinking 
> > about it for awhile I don't know why we would want to define 
> > a device name for SAS devices that is a different format than 
> > the SAS address we already have which is already unique. So 
> > we would end up with two different formats for WWN is SAS for 
> > no real good reason. Also one of the formats would be 
> > ridiculously long. 
> > 
> > Bye for now, 
> > George Penokie 
> > 
> > Dept 2C6  114-2 N212 
> > E-Mail:    gop at us.ibm.com 
> > Internal:  553-5208 
> > External: 507-253-5208   FAX: 507-253-2880 
> > 
> > 
> > 
> > 
> >                                                               
> >                                                               
> >            
> >                       "Elliott, Robert                        
> >                                                               
> >            
> >                       (Server Storage)"        To:       
> > <t10 at t10.org>                                                 
> >                 
> >                       <Elliott at hp.com>         cc:            
> >                                                               
> >            
> >                       Sent by:                 Subject:  SCSI 
> > device names                                                  
> >            
> >                       owner-t10 at t10.org                       
> >                                                               
> >            
> >                                                               
> >                                                               
> >            
> >                                                               
> >                                                               
> >            
> >                       10/22/02 07:23 PM                       
> >                                                               
> >            
> >                                                               
> >                                                               
> >            
> >                                                               
> >                                                               
> >            
> > 
> > 
> > 
> > 
> > The current rule in SAM-3 is that a device may have one 
> > device name per transport protocol.  This means, for example, 
> > that a target device with both SAS and iSCSI target ports has 
> > two device names - the iSCSI name and the SAS device name. 
> > 
> > 
> > Assuming 02-254 (WWNs for W-LUNs) passes, these would be 
> > returned as two device identifiers in VPD data: 1. SAS device 
> > name association=target device (2h) protocol identifier=SAS 
> > (6h) identifier type=NAA (3h) identifier=IEEE Registered 
> > format (NAA=5h), 8 bytes long 
> > 
> > 
> > 2. iSCSI device name 
> > association=target device (2h) 
> > protocol identifier=iSCSI (5h) 
> > identifier type=iSCSI name-based (7h)    (to be proposed in 02-419) 
> > identifier=UTF-8 format string, up to 224 bytes long 
> > 
> > 
> > It would be simpler if there were only one device name for a device.

> > 
> > 
> > Since only iSCSI has defined device names to date (SAS is 
> > just planning to include a device name now, and FCP-3 might 
> > define one too), we have an opportunity to make all device 
> > names follow the iSCSI name-based format and let each device 
> > have a single device name regardless of protocol. 
> > 
> > 
> > The iSCSI name format is a UTF-8 (similar to ASCII) string 
> > that starts with a naming authority: "iqn."  for an 
> > iSCSI-defined reverse domain name string (e.g. 
> > "iqn.2001-04.com.acme:storage.disk2.sys1.xyz") 
> > "eui."  for a hexadecimal representation of an EUI-64 
> identifier (e.g. 
> > "eui.02004567A425678D") 
> > 
> > 
> > iSCSI could easily add an "naa." type to carry a hexadecimal 
> > representation of an NAA identifier (e.g. 
> > "naa.52004567A425678D"), needed to carry the format used by 
> > SAS and Fibre Channel port names. 
> > 
> > 
> > Then, a target device with target ports of different 
> > protocols could use any string format it likes as its sole 
> > device name. 
> > 
> > 
> > Likely choices: 
> > iSCSI-only device: "iqn." (it may have no hardware names 
> > available) SAS-only device: "naa." FC-only device: "naa." 
> > SRP-only device: "eui." SBP-2-only device: "eui." iSCSI/SAS 
> > combination device: "naa." since it is already using NAA 
> > identifiers available for port names SRP/iSCSI/SAS 
> > combination device: "naa." or "eui." since it already has NAA 
> > and EUI-64s for port names 
> > 
> > 
> > This would divorce the device name concept from the transport 
> > protocols. Transport protocols could still require their 
> > devices have a device name, but wouldn't comment on the format. 
> > 
> > 
> > -- 
> > Rob Elliott, elliott at hp.com 
> > Industry Standard Server Storage Advanced Technology Hewlett-Packard

> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> * 
> * For T10 Reflector information, send a message with 
> * 'info t10' (no quotes) in the message body to majordomo at t10.org 
> 


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RE: SCSI device names I would like to see all protocols employing a = consistant name format. The ability of a device to have a name that = differs per protocol has been a headache for some time. In fact, I = would tend to claim that a name with such a property is not a name at = all, but rather some weaker degenerate identifier. Rob's suggestion has merit, as it seems to provide a = clear path from the current confusion to a situation wherein a name is = a deterministic, uniquely identifying attribute of the named = object. Joe Breher 
Exabyte Corp > -----Original Message----- 
> From: Elliott, Robert (Server Storage) [mailto:Elliott at hp.com] 
> Sent: Wednesday, October 23, 2002 9:24 = AM 
> To: George Penokie 
> Cc: t10 
> Subject: RE: SCSI device names 
> 
> 
> * From the T10 Reflector (t10 at t10.org), posted = by: 
> * ;Elliott, Robert (Server Storage); = <Elliott at hp.com> 
> * 
> A SAS-only device would still base its device = name off an NAA 
> identifier.  It would just be expressed as = 
> ;naa.5WWWXXXXYYYYZZZZ; rather 
> than as an 8 byte binary value. 
> 
> We can mandate that those identifiers still = share the NAA 
> namespace (as 
> ;eui.; would share the EUI-64 = namespace). 
> 
> What it helps solve is a device that has both = ports using different 
> transport protocols, where two or more device = names would be needed 
> under current rules.  This is a big = complication for 
> software. Since the 
> string format is capable of expressing all 3 in = use today - ;iqn.; 
> ;eui.; and ;naa.; - it = seems like the best candidate. 
> 
> This problem also affects the logical unit name = (association 0h).  A 
> native SAS or FC device will want to use an NAA = format; an InfiniBand 
> SRP device will want to use an EUI-64 format; = an iSCSI device 
> will want 
> to use an ;iqn.; based format.  = If the target device has target ports 
> with all those protocols, how does it = choose?  I think the only answer 
> is ;any of them it wants.; 
> 
> -- 
> Rob Elliott, elliott at hp.com 
> Industry Standard Server Storage Advanced = Technology 
> Hewlett-Packard 
> 
> 
> 
> > -----Original Message----- 
> > From: George Penokie [mailto:gop at us.ibm.com] 
> > Sent: Wednesday, October 23, 2002 10:03 = AM 
> > To: Elliott, Robert (Server = Storage) 
> > Cc: t10 
> > Subject: Re: SCSI device names 
> > 
> > 
> > 
> > 
> > 
> > 
> > Rob, 
> > My first reaction was 'are you = crazy'!  My second reaction 
> > was 'we maybe that would be a good idea'. = But after thinking 
> > about it for awhile I don't know why we = would want to define 
> > a device name for SAS devices that is a = different format than 
> > the SAS address we already have which is = already unique. So 
> > we would end up with two different formats = for WWN is SAS for 
> > no real good reason. Also one of the = formats would be 
> > ridiculously long. 
> > 
> > Bye for now, 
> > George Penokie 
> > 
> > Dept 2C6  114-2 N212 
> > E-Mail:    = gop at us.ibm.com 
> > Internal:  553-5208 
> > External: 507-253-5208   FAX: = 507-253-2880 
> > 
> > 
> > 
> > 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           = ;Elliott, = Robert           =             = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           = (Server Storage);        = To:       
> > = <t10 at t10.org>        ;           ;           ;           ;    
> = >           bsp;     
> = >           bsp;           = <Elliott at hp.com>         = cc:            = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           Sent = by:           sp;     Subject:  SCSI 
> > device = names           nbsp;           nbsp;           nbsp;           nbsp;  
> = >            = 
> = >           bsp;           = owner-t10 at t10.org         nbsp;           nbsp; 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> >       bsp;           bsp;           bsp;           bsp;           bsp;       
> = >            = 
> = >           bsp;           = 10/22/02 07:23 = PM           p;           
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >           bsp;           bsp;           bsp;           bsp;           bsp;   
> = >            = 
> > 
> > 
> > 
> > 
> > The current rule in SAM-3 is that a device = may have one 
> > device name per transport protocol.  = This means, for example, 
> > that a target device with both SAS and = iSCSI target ports has 
> > two device names - the iSCSI name and the = SAS device name. 
> > 
> > 
> > Assuming 02-254 (WWNs for W-LUNs) passes, = these would be 
> > returned as two device identifiers in VPD = data: 1. SAS device 
> > name association=3Dtarget device (2h) = protocol identifier=3DSAS 
> > (6h) identifier type=3DNAA (3h) = identifier=3DIEEE Registered 
> > format (NAA=3D5h), 8 bytes long 
> > 
> > 
> > 2. iSCSI device name 
> > association=3Dtarget device (2h) 
> > protocol identifier=3DiSCSI (5h) 
> > identifier type=3DiSCSI name-based = (7h)    (to be proposed in 02-419) 
> > identifier=3DUTF-8 format string, up to = 224 bytes long 
> > 
> > 
> > It would be simpler if there were only one = device name for a device. 
> > 
> > 
> > Since only iSCSI has defined device names = to date (SAS is 
> > just planning to include a device name = now, and FCP-3 might 
> > define one too), we have an opportunity to = make all device 
> > names follow the iSCSI name-based format = and let each device 
> > have a single device name regardless of = protocol. 
> > 
> > 
> > The iSCSI name format is a UTF-8 (similar = to ASCII) string 
> > that starts with a naming authority: = ;iqn.;  for an 
> > iSCSI-defined reverse domain name string = (e.g. 
> > = ;iqn.2001-04.com.acme:storage.disk2.sys1.xyz;) 
> > ;eui.;  for a hexadecimal = representation of an EUI-64 
> identifier (e.g. 
> > ;eui.02004567A425678D;) 
> > 
> > 
> > iSCSI could easily add an ;naa.; = type to carry a hexadecimal 
> > representation of an NAA identifier (e.g. = 
> > ;naa.52004567A425678D;), needed = to carry the format used by 
> > SAS and Fibre Channel port names. 
> > 
> > 
> > Then, a target device with target ports of = different 
> > protocols could use any string format it = likes as its sole 
> > device name. 
> > 
> > 
> > Likely choices: 
> > iSCSI-only device: ;iqn.; (it = may have no hardware names 
> > available) SAS-only device: = ;naa.; FC-only device: ;naa.; 
> > SRP-only device: ;eui.; = SBP-2-only device: ;eui.; iSCSI/SAS 
> > combination device: ;naa.; since = it is already using NAA 
> > identifiers available for port names = SRP/iSCSI/SAS 
> > combination device: ;naa.; or = ;eui.; since it already has NAA 
> > and EUI-64s for port names 
> > 
> > 
> > This would divorce the device name concept = from the transport 
> > protocols. Transport protocols could still = require their 
> > devices have a device name, but wouldn't = comment on the format. 
> > 
> > 
> > -- 
> > Rob Elliott, elliott at hp.com 
> > Industry Standard Server Storage Advanced = Technology Hewlett-Packard 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> * 
> * For T10 Reflector information, send a message = with 
> * 'info t10' (no quotes) in the message body to = majordomo at t10.org 
> 
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