[Bug 1032550] Re: [multipath] failed to get sysfs information

[Peter Petrakis]

@Ronald

First, please attach http://www.rmoesbergen.nl/vmcore-crash.tgz to the bug, launchpad
can handle it just fine. Also, this is going to take awhile. We're off all next week so don't
expect any movement on this until early-mid Jan. Feel free to ping me if I forget.

Also, at what time did your testing start? I'm seeing this everywhere almost immediately
         emc: ALUA failover mode detected

Could you also illustrate what the steady state target distribution
should be?

I see targets like this:
        sd 3:0:0:0: [sdb] 41943040 512-byte logical blocks: (21.4 GB/20.0 GiB)
 
in the minority compared to
        sd 3:0:0:1: [sdc] 419430400 512-byte logical blocks: (214 GB/200 GiB)

Wondering if your SAN is misreporting READ CAPACITY.

The dump looks good. Immediately I can tell you that all  the scsi hosts
are still RUNNING and not in error handling. It looks like I'll have examine
the scsi target states and the dm tables.  

So there are these stuck processes

crash> ps | grep UN
   1530      2   0  ffff880415ef9700  UN   0.0       0      0  [jbd2/dm-1-8]
   2180      2   1  ffff88040613ae00  UN   0.0       0      0  [flush-252:1]
   4739      1   2  ffff880418e70000  UN   5.8 16426520 1029488  mysqld

Which adds up, you can't write back.

This also looks really suspicious.

[62856.457650] end_request: I/O error, dev sdf, sector 21272960
[62856.457966] device-mapper: multipath: Failing path 8:80.
[62856.462495] scsi 3:0:0:0: emc: Detached
[62856.462730] device-mapper: multipath: Failing path 8:80.
[62856.462798] sd 4:0:0:0: emc: ALUA failover mode detected
[62856.462806] sd 4:0:0:0: emc: at SP A Port 0 (owned, default SP A)
# sketchy
[62856.462814] device-mapper: multipath: Could not failover the device: Handler scsi_dh_emc Error 15.

# it looks like it's retrying

[63122.241178] sd 3:0:1:0: [sdf]  Result: hostbyte=DID_NO_CONNECT driverbyte=DRIVER_OK
[63122.241185] sd 3:0:1:0: [sdf] CDB: Write(10): 2a 00 01 44 b4 d8 00 00 20 00
[63122.241198] end_request: I/O error, dev sdf, sector 21279960
[63122.241513] device-mapper: multipath: Failing path 8:80.
[63122.244865] scsi 3:0:0:0: emc: Detached
[63122.245045] sd 4:0:0:0: emc: ALUA failover mode detected
[63122.245053] sd 4:0:0:0: emc: at SP A Port 0 (owned, default SP A)
# sketchy
[63122.245062] device-mapper: multipath: Could not failover the device: Handler scsi_dh_emc Error 15. 

...
which comes from: [drivers/md/dm-mpath.c]
        case SCSI_DH_NOSYS:
                if (!m->hw_handler_name) {
                        errors = 0;
                        break;
                }
                DMERR("Could not failover the device: Handler scsi_dh_%s "
                      "Error %d.", m->hw_handler_name, errors);
                /*
                 * Fail path for now, so we do not ping pong
                 */
                fail_path(pgpath);
                break;

Hey, was this intentional?

[    0.018792] Hardware name: ProLiant DL380p Gen8
[    0.018794] Your BIOS is broken and requested that x2apic be disabled
[    0.018795] This will leave your machine vulnerable to irq-injection attacks
[    0.018796] Use 'intremap=no_x2apic_optout' to override BIOS request

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Title:
  [multipath]  failed to get sysfs information

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