Re: mpt2sas: /sysfs sas_address entries do not show individual port sas addresses.

[Douglas Gilbert <dgilbert@interlog.com>]

On 11-08-17 06:42 AM, Benjamin ESTRABAUD wrote:
> Hi,
>
> I am seing a bug with the mpt2sas driver from the "Release 2.6.35.11" kernel
> (commit d6c90f5b218c1ddf1496045e3939b1c960c7cb9f, tag v2.6.35.11, long term
> support kernel).
>
> I have a system that has both a LSI 1068e B3 (3G) based HBA (a SAS3801E) as well
> as a LSI SAS 2008 03 (6G) HBA (a SAS9200-8e). They both work as expected, but I
> am seeing a major difference in their respective /sysfs structure, especially
> regarding their phy's "sas_address" field, which seems to be a bug.
>
> The 3G HBA's SAS addresses are associated to a specific port in sysfs, while the
> 6G one are associated to the actual HBA.
>
> The 3G HBA is configured to have two wide ports, made up of 4 phys each, port 0
> and port 1, and same configuration applies for the 6G HBA.
> The ports are not in "auto" nor in narrow.
> There are only two enabled ports on each HBA.
>
>
> I get the following sysfs entries regarding the 3G one:
>
> # cat /sys/class/sas_host/host5/device/phy-5\:0/sas_phy\:phy-5\:0/sas_address
> 0x50015b2a2000060f
> # cat /sys/class/sas_host/host5/device/phy-5\:1/sas_phy\:phy-5\:1/sas_address
> 0x50015b2a2000060f
> # cat /sys/class/sas_host/host5/device/phy-5\:2/sas_phy\:phy-5\:2/sas_address
> 0x50015b2a2000060f
> # cat /sys/class/sas_host/host5/device/phy-5\:3/sas_phy\:phy-5\:3/sas_address
> 0x50015b2a2000060f
> # cat /sys/class/sas_host/host5/device/phy-5\:4/sas_phy\:phy-5\:4/sas_address
> 0x50015b2a20000613
> # cat /sys/class/sas_host/host5/device/phy-5\:5/sas_phy\:phy-5\:5/sas_address
> 0x50015b2a20000613
> # cat /sys/class/sas_host/host5/device/phy-5\:6/sas_phy\:phy-5\:6/sas_address
> 0x50015b2a20000613
> # cat /sys/class/sas_host/host5/device/phy-5\:7/sas_phy\:phy-5\:7/sas_address
> 0x50015b2a20000613
>
> And these ones on the 6G:
>
> # cat /sys/class/sas_host/host0/device/phy-0\:0/sas_phy\:phy-0\:0/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:1/sas_phy\:phy-0\:1/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:2/sas_phy\:phy-0\:2/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:3/sas_phy\:phy-0\:3/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:4/sas_phy\:phy-0\:4/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:5/sas_phy\:phy-0\:5/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:6/sas_phy\:phy-0\:6/sas_address
> 0x500605b002c99150
> # cat /sys/class/sas_host/host0/device/phy-0\:7/sas_phy\:phy-0\:7/sas_address
> 0x500605b002c99150
>
> As we can see above, the 3G HBA's phy "sas_address" sysfs entry displays correct
> information: A single SAS address for phy 0-3 and a single one for phy 4-7.
>
> As we can also see using LSIUtil, each phy is numbered from a base address and
> incremented.
> Also, the port sas address corresponds to the address of the starting phy of the
> port.
> Port0's sas address is "0x50015b2a2000060f", which corresponds to the HBA's phy0
> sas address.
> Port1's sas address is "0x50015b2a20000613" which corresponds to the HBA's phy3
> sas address, the starting phys for each of these ports.
>
> Output of menu "16" from LSIUtil on the 3G HBA (1068e):
>
> B___T SASAddress PhyNum Handle Parent Type
> 50015b2a2000060f 0001 SAS Initiator
> 50015b2a20000610 0002 SAS Initiator
> 50015b2a20000611 0003 SAS Initiator
> 50015b2a20000612 0004 SAS Initiator
> 50015b2a20000613 0005 SAS Initiator
> 50015b2a20000614 0006 SAS Initiator
> 50015b2a20000615 0007 SAS Initiator
> 50015b2a20000616 0008 SAS Initiator
>
> However, when looking at the 6G HBA's sysfs information above, we can see that
> all phy's SAS address are identical, like if there was a single port made up of
> the entire 8 phys from the HBA.
>
> When looking at LSIUtil below, we get more strangeness, where all phys have
> exactly the same SAS address:
>
> Output of menu "16" from LSIUtil on the 6G HBA (2008):
>
> B___T SASAddress PhyNum Handle Parent Type
> 500605b002c99150 0001 SAS Initiator
> 500605b002c99150 0002 SAS Initiator
> 500605b002c99150 0003 SAS Initiator
> 500605b002c99150 0004 SAS Initiator
> 500605b002c99150 0005 SAS Initiator
> 500605b002c99150 0006 SAS Initiator
> 500605b002c99150 0007 SAS Initiator
> 500605b002c99150 0008 SAS Initiator
>
> But looking at LSIUtil's menu "13" on the 6G HBA proves that we indeed have 2
> ports on that HBA:
>
> PhyNum Link MinRate MaxRate Initiator Target Port
> 0 Enabled 1.5 6.0 Enabled Disabled 0
> 1 Enabled 1.5 6.0 Enabled Disabled 0
> 2 Enabled 1.5 6.0 Enabled Disabled 0
> 3 Enabled 1.5 6.0 Enabled Disabled 0
> 4 Enabled 1.5 6.0 Enabled Disabled 1
> 5 Enabled 1.5 6.0 Enabled Disabled 1
> 6 Enabled 1.5 6.0 Enabled Disabled 1
> 7 Enabled 1.5 6.0 Enabled Disabled 1
>
> Somehow, on the 6G HBA using mpt2sas, all phys from a HBA seem to have the same
> SAS address, and all ports on that HBA, whether narrow (1Phy) or wide (4Phys),
> will seemingly have the same SAS address.
>
> This is causing a good few issues with our system scripting, as we relied on SAS
> addresses to identify ports.
>
> I searched on Google extensively before posting and couldn't find any mention of
> this issue.
>
> Is this a known issue? If so, will this be resolved in a later version of the
> driver?

Ben,
I noticed something similar when comparing LSI 3 Gbps and
6 Gbps SAS HBAs. I was looking at the same thing but from
an expander's perspective. I'm not so sure that the newer
6 Gbps HBAs are incorrect. IOW the older 3 Gbps HBAs might
be playing some tricks with the HBA's SAS addresses so that
it is not possible to set up a wide link spanning the
lower and upper 4-phy banks (e.g. a 5 phy wide link).

Do you know a reason why it is not preferably for every
phy on a SAS HBA to respond with the same SAS address?


As a practical matter a SAS HBA needs a single SAS address,
preferably printed on the board or its box. Then if you
manage to wipe its SAS address (e.g. by erasing its flash
to move from IR to IT firmware) then you know which SAS
address to re-instate :-)

Doug Gilbert