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Message #180897
[Bug 1567602] Comment bridged from LTC Bugzilla
------- Comment From BBLOCK@xxxxxxxxxx 2016-05-25 12:17 EDT-------
Hello Canonical,
after talking with different folks here and trying to figure out why this
fails, we found the likely bug here, and its in the kernel after all.
When scanning the SCSI LUNs behind a found FCP remote port (during activation
of a FCP device) linux will also try to attach a device-handler to each found
LUN - with our storages it will try to attach the ALUA device handler
(scsi_dh_alua). In parallel to attaching the DH it will also activate the
scsi-disk driver for the found LUN. Those two will run in parallel. Schematic
this looks roughly like this (I hope this ASCII-Art survives in the Bugzilla):
Thread A | Thread B
|
scsi_report_lun_scan() |
: |
| send REPORT LUNS |
: |
| for each LUN sequentially: |
: : |
+------>| scsi_probe_and_add_lun() |
| : | Kick SD for this LUN:
| | scsi_dh_add_device() | :
| : | :
| | alua_bus_attach() | :
| : | :
| | alua_vpd_inquiry() | | sd_spinup_disk()
| :
| .............
| :
| | continue with next LUN
+-------+
:
| exit
v
Now it happens that sd_spinup_disk() sends the first command (a TUR) that is
not an INQURY or REPORT LUNS in parallel to the INQURY that is send by
alua_vpd_inquiry().
This TUR will raise a Check Condition with Sense Unit Attention because of a
reset in the storage - this is normal if the LUN was just attached the first
time after the remote port open (SAM-4, 5.14).
And because the storage has a default value of QErr=01b set in the Control
Mode Page (SPC-4, 7.5.8) this raised Check Condition will cause an Abort of all
running command in the same task set (same I_T nexus; SAM-4, 5.6).
But for this Abort no status will be returned for the affected commands in
the same I_T nexus as the command that received the Check Condition (also
SPC-4, 7.5.8).
So in essence the storage just forgets all other commands, other than the
first TUR, and that gets the Unit Attention (all other commands send before the
TUR are either INQURY or REPORT LUNS, and those will never raise a Unit
Attention; SAM-4, 5.14).
This is why the INQURY send by alua_vpd_inquiry() will ultimately time out
after one minute. And this will abort the whole LUN scan in
scsi_report_lun_scan().
Ofc this depends on specific timings - when arrives the INQURY and when the
TUR. But like written in this report, we have seen this in multiple completely
independent setups.
I looked at changes made by the maintainer of scsi_dh_alua upstream since
release of 4.4 and there has been some very substantial changes (recent changes
were titled "ALUA device handler update, part II" on LKML). And those changes
mitigate this problem. They change the timing of commands sent in scsi_dh_alua
and remove the send of own INQURYs completely (it uses already gathered
information instead).
With the removed INQURY and the changed timing, there are no overlaps
anymore and the LUN-scan doesn't abort half-way through (which BTW. was also
changed in 4.5: failures in scsi_dh_add_device() won't abort the whole scan
anymore).
In my own small tests I couldn't reproduce this problem with 4.6 yet.
Although I might add, the main issue here - sending commands in parallel with
QErr set to 01b might lead to forgotten commands in case of a Check Condition
in the same I_T nexus - is not yet fixed in my opinion.
I have spend quite some time reading the mentioned parts in the SCSI standards
and have not reached any other conclusion as of now, but I am also not that
fluent with them yet.
I hope this helps you finding a good solution here.
- Benjamin
--
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https://bugs.launchpad.net/bugs/1567602
Title:
FCP devices are not detected correctly nor deterministically
Status in Release Notes for Ubuntu:
Fix Released
Status in Ubuntu on IBM z Systems:
Triaged
Status in linux package in Ubuntu:
Confirmed
Bug description:
Release notes:
Usage of SCSI LUNs on DS8870 Storage server with μCode Bundles 87.51.xx.0 (LMC 7.7.51.xx) via NPIV enabled zfcp adaptors causes detection issues. LP #1567602 In that case do not use NPIV enabled zfcp adaptors.
Scenario:
Using Installer 432.
No DASD devices, just two FCP CHPIDs with two LUNs each (configured for NPIV), provided via parmfile.
I expect the installer to probe and detect the LUNs automatically once I enable the FCP CHPIDs.
Repeated five times, I got different results each time. Detected LUNs
vary between 2 and 4. One time 3 LUNs appear on SCSI1 and one on SCSI2
which looks especially odd to me.
Subsequent steps to create partitions and file systems in the
installer fail.
Following is one of the five cases with more details:
After enabling CHPID 192b:
~ # cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 1077493890
Vendor: IBM Model: 2107900 Rev: 1.27
Type: Direct-Access ANSI SCSI revision: 05
dmesg showing:
[ 221.738816] qdio: 0.0.192b ZFCP on SC f using AI:1 QEBSM:1 PRI:1 TDD:1 SIGA: W A
[ 226.895139] scsi 0:0:0:1077493890: Direct-Access IBM 2107900 1.27 PQ: 0 ANSI: 5
[ 226.895816] sd 0:0:0:1077493890: alua: supports implicit TPGS
[ 226.896673] sd 0:0:0:1077493890: [sda] 41943040 512-byte logical blocks: (21.5 GB/20.0 GiB)
[ 226.897825] sd 0:0:0:1077493890: [sda] Write Protect is off
[ 226.897827] sd 0:0:0:1077493890: [sda] Mode Sense: ed 00 00 08
[ 226.898145] sd 0:0:0:1077493890: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 226.902571] sd 0:0:0:1077493890: [sda] Attached SCSI disk
[ 287.117057] sd 0:0:0:1077493890: alua: evpd inquiry failed with 30000
[ 287.117062] sd 0:0:0:1077493890: alua: Attach failed (-22)
[ 287.117064] sd 0:0:0:1077493890: failed to add device handler: -22
[ 287.147303] scsi 0:0:0:0: Unexpected response from lun 1077493890 while scanning, scan aborted
As second step, I additionally enable CHPID 196b:
~ # cat /proc/scsi/scsi
Attached devices:
Host: scsi0 Channel: 00 Id: 00 Lun: 1077493890
Vendor: IBM Model: 2107900 Rev: 1.27
Type: Direct-Access ANSI SCSI revision: 05
Host: scsi1 Channel: 00 Id: 00 Lun: 1077493890
Vendor: IBM Model: 2107900 Rev: 1.27
Type: Direct-Access ANSI SCSI revision: 05
dmesg showing:
[ 384.277394] scsi host1: zfcp
[ 384.286516] qdio: 0.0.196b ZFCP on SC 10 using AI:1 QEBSM:1 PRI:1 TDD:1 SIGA: W A
[ 385.377511] scsi 1:0:0:1077493890: Direct-Access IBM 2107900 1.27 PQ: 0 ANSI: 5
[ 385.378120] sd 1:0:0:1077493890: alua: supports implicit TPGS
[ 385.378781] sd 1:0:0:1077493890: [sdb] 41943040 512-byte logical blocks: (21.5 GB/20.0 GiB)
[ 385.380097] sd 1:0:0:1077493890: [sdb] Write Protect is off
[ 385.380099] sd 1:0:0:1077493890: [sdb] Mode Sense: ed 00 00 08
[ 385.380408] sd 1:0:0:1077493890: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 385.384969] sd 1:0:0:1077493890: [sdb] Attached SCSI disk
[ 446.117041] sd 1:0:0:1077493890: alua: evpd inquiry failed with 30000
[ 446.117046] sd 1:0:0:1077493890: alua: Attach failed (-22)
[ 446.117048] sd 1:0:0:1077493890: failed to add device handler: -22
[ 446.147158] scsi 1:0:0:0: Unexpected response from lun 1077493890 while scanning, scan aborted
Next, the installer warns that no disk drives were detected.
I checked this on a system (installer 445) with two NPIV enabled FCP
devices that have 4 LUNS each. I only get the first of four LUNs per
adaptor:
Apr 6 12:57:08 anna[2607]: DEBUG: retrieving zipl-installer 0.0.33ubuntu2
Apr 6 12:57:08 anna[2607]: 2016-04-06 12:57:08 URL:http://ports.ubuntu.com//pool/main/z/zipl-installer/zipl-installer_0.0.33ubuntu2_s390x.udeb [4994/4994] -> "/var/cache/anna/zipl-installer_0.0.33ubuntu2_s390x.udeb" [1]
Apr 6 12:57:09 main-menu[384]: INFO: Menu item 'driver-injection-disk-detect' selected
Apr 6 12:57:10 main-menu[384]: INFO: Menu item 'user-setup-udeb' selected
Apr 6 12:57:10 main-menu[384]: INFO: Menu item 'clock-setup' selected
Apr 6 12:57:10 main-menu[384]: INFO: Menu item 's390-dasd' selected
Apr 6 12:57:10 s390-dasd[6877]: INFO: s390-dasd: no channel found
Apr 6 12:57:10 main-menu[384]: INFO: Menu item 's390-zfcp' selected
Apr 6 12:57:10 s390-zfcp[6891]: DEBUG: DETECT: The zfcp device driver is not loaded
Apr 6 12:57:10 s390-zfcp[6891]: WARNING **: Could not open directory: /sys/bus/ccw/drivers/zfcp/: No such file or directory
Apr 6 12:57:11 main-menu[384]: INFO: Menu item 'disk-detect' selected
Apr 6 12:57:11 anna-install: Installing mmc-modules
Apr 6 12:57:11 disk-detect: insmod /lib/modules/4.4.0-17-generic/kernel/drivers/scsi/device_handler/scsi_dh_rdac.ko
Apr 6 12:57:11 disk-detect: insmod /lib/modules/4.4.0-17-generic/kernel/drivers/scsi/device_handler/scsi_dh_alua.ko
Apr 6 12:57:11 disk-detect: insmod /lib/modules/4.4.0-17-generic/kernel/drivers/scsi/device_handler/scsi_dh_hp_sw.ko
Apr 6 12:57:11 disk-detect: insmod /lib/modules/4.4.0-17-generic/kernel/drivers/scsi/device_handler/scsi_dh_emc.ko
Apr 6 12:57:11 kernel: [ 40.509881] rdac: device handler registered
Apr 6 12:57:11 kernel: [ 40.513219] alua: device handler registered
Apr 6 12:57:11 kernel: [ 40.515517] hp_sw: device handler registered
Apr 6 12:57:11 kernel: [ 40.517572] emc: device handler registered
Apr 6 12:57:11 net/hw-detect.hotplug: Detected hotpluggable network interface encf5f0
Apr 6 12:57:11 net/hw-detect.hotplug: Detected hotpluggable network interface lo
Apr 6 12:57:11 apt-install: Queueing package udev for later installation
Apr 6 12:57:11 apt-install: Queueing package pciutils for later installation
Apr 6 12:57:12 check-missing-firmware: looking at dmesg for the first time
Apr 6 12:57:12 check-missing-firmware: saving timestamp for a later use: [ 40.517572]
Apr 6 12:57:12 check-missing-firmware: /dev/.udev/firmware-missing does not exist, skipping
Apr 6 12:57:12 check-missing-firmware: /run/udev/firmware-missing does not exist, skipping
Apr 6 12:57:12 check-missing-firmware: no missing firmware in loaded kernel modules
Apr 6 12:58:29 main-menu[384]: (process:6908): unknown udeb mmc-modules
Apr 6 12:58:29 main-menu[384]: INFO: Menu item 'disk-detect' succeeded but requested to be left unconfigured.
Apr 6 12:58:31 main-menu[384]: INFO: Menu item 's390-zfcp' selected
Apr 6 12:58:31 s390-zfcp[7752]: DEBUG: DETECT: Added FCP device: 0.0.1904: online=0 npiv=0
Apr 6 12:58:31 s390-zfcp[7752]: DEBUG: DETECT: Added FCP device: 0.0.1944: online=0 npiv=0
Apr 6 12:58:31 s390-zfcp[7752]: DEBUG: DETECT: Automatic LUN scanning is enabled
Apr 6 12:58:31 s390-zfcp[7752]: DEBUG: PRESEED: No preseed data available
Apr 6 12:58:40 s390-zfcp[7752]: DEBUG: SELECT: Using FCP device 0.0.1904
Apr 6 12:58:40 kernel: [ 129.591146] scsi host0: scsi_eh_0: sleeping
Apr 6 12:58:40 kernel: [ 129.591163] scsi host0: zfcp
Apr 6 12:58:40 kernel: [ 129.598187] qdio: 0.0.1904 ZFCP on SC f using AI:1 QEBSM:1 PRI:1 TDD:1 SIGA: W A
Apr 6 12:58:41 s390-zfcp[7752]: DEBUG: ENABLE: Activated FCP device 0.0.1904 (npiv=1)
Apr 6 12:58:41 kernel: [ 130.873257] scsi 0:0:0:0: scsi scan: INQUIRY pass 1 length 36
Apr 6 12:58:41 kernel: [ 130.873581] scsi 0:0:0:0: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:41 kernel: [ 130.873593] scsi 0:0:0:0: scsi scan: INQUIRY pass 2 length 164
Apr 6 12:58:41 kernel: [ 130.873802] scsi 0:0:0:0: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:41 kernel: [ 130.873807] scsi 0:0:0:0: scsi scan: peripheral device type of 31, no device added
Apr 6 12:58:41 kernel: [ 130.874148] scsi 0:0:0:0: scsi scan: Sending REPORT LUNS to (try 0)
Apr 6 12:58:41 kernel: [ 130.875003] scsi 0:0:0:0: scsi scan: REPORT LUNS successful (try 0) result 0x0
Apr 6 12:58:41 kernel: [ 130.875005] scsi 0:0:0:0: scsi scan: REPORT LUN scan
Apr 6 12:58:41 kernel: [ 130.875176] scsi 0:0:0:1074937986: scsi scan: INQUIRY pass 1 length 36
Apr 6 12:58:41 kernel: [ 130.875395] scsi 0:0:0:1074937986: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:41 kernel: [ 130.875399] scsi 0:0:0:1074937986: scsi scan: INQUIRY pass 2 length 164
Apr 6 12:58:41 kernel: [ 130.875608] scsi 0:0:0:1074937986: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:41 kernel: [ 130.875613] scsi 0:0:0:1074937986: Direct-Access IBM 2107900 1.27 PQ: 0 ANSI: 5
Apr 6 12:58:41 kernel: [ 130.876181] sd 0:0:0:1074937986: alua: supports implicit TPGS
Apr 6 12:58:41 kernel: [ 130.876323] sd 0:0:0:1074937986: tag#1 Done: SUCCESS Result: hostbyte=DID_OK driverbyte=DRIVER_OK
Apr 6 12:58:41 kernel: [ 130.876326] sd 0:0:0:1074937986: tag#1 CDB: Test Unit Ready 00 00 00 00 00 00
Apr 6 12:58:41 kernel: [ 130.876328] sd 0:0:0:1074937986: tag#1 Sense Key : Unit Attention [current]
Apr 6 12:58:41 kernel: [ 130.876333] sd 0:0:0:1074937986: tag#1 Add. Sense: Power on, reset, or bus device reset occurred
Apr 6 12:58:41 kernel: [ 130.876722] sd 0:0:0:1074937986: [sda] 41943040 512-byte logical blocks: (21.5 GB/20.0 GiB)
Apr 6 12:58:41 kernel: [ 130.877759] sd 0:0:0:1074937986: [sda] Write Protect is off
Apr 6 12:58:41 kernel: [ 130.877761] sd 0:0:0:1074937986: [sda] Mode Sense: ed 00 00 08
Apr 6 12:58:41 kernel: [ 130.878085] sd 0:0:0:1074937986: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
Apr 6 12:58:41 kernel: [ 130.878295] sd 0:0:0:1074937986: tag#1 Done: SUCCESS Result: hostbyte=DID_TARGET_FAILURE driverbyte=DRIVER_OK
Apr 6 12:58:41 kernel: [ 130.878297] sd 0:0:0:1074937986: tag#1 CDB: Report supported operation codes a3 0c 01 12 00 00 00 00 02 00 00 00
Apr 6 12:58:41 kernel: [ 130.878298] sd 0:0:0:1074937986: tag#1 Sense Key : Illegal Request [current]
Apr 6 12:58:41 kernel: [ 130.878300] sd 0:0:0:1074937986: tag#1 Add. Sense: Invalid field in cdb
Apr 6 12:58:41 kernel: [ 130.882710] sd 0:0:0:1074937986: [sda] Attached SCSI disk
Apr 6 12:58:43 s390-zfcp[7752]: DEBUG: POPULATE LUN TREE: 0.0.1904:0x50050763070845e3:0x4082401200000000 [0:0:0:1074937986]
Apr 6 12:58:43 s390-zfcp[7752]: DEBUG: WRITE CONFIG: /etc/sysconfig/hardware/config-ccw-0.0.1904
Apr 6 12:58:47 s390-zfcp[7752]: DEBUG: SELECT: Using FCP device 0.0.1944
Apr 6 12:58:47 kernel: [ 136.279385] scsi host1: scsi_eh_1: sleeping
Apr 6 12:58:47 kernel: [ 136.279396] scsi host1: zfcp
Apr 6 12:58:47 kernel: [ 136.290784] qdio: 0.0.1944 ZFCP on SC 10 using AI:1 QEBSM:1 PRI:1 TDD:1 SIGA: W A
Apr 6 12:58:52 s390-zfcp[7752]: DEBUG: ENABLE: Activated FCP device 0.0.1944 (npiv=1)
Apr 6 12:58:52 kernel: [ 141.278081] scsi 1:0:0:0: scsi scan: INQUIRY pass 1 length 36
Apr 6 12:58:52 kernel: [ 141.278691] scsi 1:0:0:0: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:52 kernel: [ 141.278698] scsi 1:0:0:0: scsi scan: INQUIRY pass 2 length 164
Apr 6 12:58:52 kernel: [ 141.278910] scsi 1:0:0:0: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:52 kernel: [ 141.278915] scsi 1:0:0:0: scsi scan: peripheral device type of 31, no device added
Apr 6 12:58:52 kernel: [ 141.279221] scsi 1:0:0:0: scsi scan: Sending REPORT LUNS to (try 0)
Apr 6 12:58:52 kernel: [ 141.280115] scsi 1:0:0:0: scsi scan: REPORT LUNS successful (try 0) result 0x0
Apr 6 12:58:52 kernel: [ 141.280119] scsi 1:0:0:0: scsi scan: REPORT LUN scan
Apr 6 12:58:52 kernel: [ 141.280296] scsi 1:0:0:1074937986: scsi scan: INQUIRY pass 1 length 36
Apr 6 12:58:52 kernel: [ 141.280507] scsi 1:0:0:1074937986: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:52 kernel: [ 141.280511] scsi 1:0:0:1074937986: scsi scan: INQUIRY pass 2 length 164
Apr 6 12:58:52 kernel: [ 141.280693] scsi 1:0:0:1074937986: scsi scan: INQUIRY successful with code 0x0
Apr 6 12:58:52 kernel: [ 141.280698] scsi 1:0:0:1074937986: Direct-Access IBM 2107900 1.27 PQ: 0 ANSI: 5
Apr 6 12:58:52 kernel: [ 141.281519] sd 1:0:0:1074937986: alua: supports implicit TPGS
Apr 6 12:58:52 kernel: [ 141.281798] sd 1:0:0:1074937986: tag#1 Done: SUCCESS Result: hostbyte=DID_OK driverbyte=DRIVER_OK
Apr 6 12:58:52 kernel: [ 141.281801] sd 1:0:0:1074937986: tag#1 CDB: Test Unit Ready 00 00 00 00 00 00
Apr 6 12:58:52 kernel: [ 141.281802] sd 1:0:0:1074937986: tag#1 Sense Key : Unit Attention [current]
Apr 6 12:58:52 kernel: [ 141.281804] sd 1:0:0:1074937986: tag#1 Add. Sense: Power on, reset, or bus device reset occurred
Apr 6 12:58:52 kernel: [ 141.282130] sd 1:0:0:1074937986: [sdb] 41943040 512-byte logical blocks: (21.5 GB/20.0 GiB)
Apr 6 12:58:52 kernel: [ 141.283353] sd 1:0:0:1074937986: [sdb] Write Protect is off
Apr 6 12:58:52 kernel: [ 141.283355] sd 1:0:0:1074937986: [sdb] Mode Sense: ed 00 00 08
Apr 6 12:58:52 kernel: [ 141.283637] sd 1:0:0:1074937986: [sdb] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
Apr 6 12:58:52 kernel: [ 141.283758] sd 1:0:0:1074937986: tag#1 Done: SUCCESS Result: hostbyte=DID_TARGET_FAILURE driverbyte=DRIVER_OK
Apr 6 12:58:52 kernel: [ 141.283760] sd 1:0:0:1074937986: tag#1 CDB: Report supported operation codes a3 0c 01 12 00 00 00 00 02 00 00 00
Apr 6 12:58:52 kernel: [ 141.283761] sd 1:0:0:1074937986: tag#1 Sense Key : Illegal Request [current]
Apr 6 12:58:52 kernel: [ 141.283763] sd 1:0:0:1074937986: tag#1 Add. Sense: Invalid field in cdb
Apr 6 12:58:52 kernel: [ 141.288209] sd 1:0:0:1074937986: [sdb] Attached SCSI disk
Apr 6 12:58:53 s390-zfcp[7752]: DEBUG: POPULATE LUN TREE: 0.0.1944:0x50050763071845e3:0x4082401200000000 [1:0:0:1074937986]
Apr 6 12:58:53 s390-zfcp[7752]: DEBUG: WRITE CONFIG: /etc/sysconfig/hardware/config-ccw-0.0.1944
It looks like the LUN scan is being terminated.
Kernel parms with: scsi_mod.scsi_logging_level=4605 zfcp.dbflevel=6 zfcp.dbfsize=100
Re-testing with installer version 445 + udeb packages from 2016-04-07
s390-dasd 0.0.36ubuntu1, s390-zfcp 1.0.2ubuntu1, multipath-udeb
0.5.0+git1.656f8865-5ubuntu2, disk-detect 1.117ubuntu1
Some observations:
1. With one path only, the scanning/detection of all LUNs worked deterministically and correctly (including the final re-IPL after successful installation).
2. With two paths, but without the parmfile option 'disk-detect/multipath/enable=true', the LUNs were all detected, but once for every path. I did not want to continue installation that way.
3. With two paths and with the option 'disk-detect/multipath/enable=true', the multipath program was loaded and multipathing was set up correctly. ...
4. ... installation completed fine then...
5. .... but the final re-IPL after successful installation failed. Attaching last console messages of the IPL:
6. I could also see a difference in filesystem creation time for multipath and single path:
with multipathing (2 paths)
Apr 7 15:27:33 partman: mke2fs 1.42.13 (17-May-2015)
Apr 7 15:28:34 kernel: [ 559.624851] EXT4-fs (dm-4): mounted filesystem with ordered data mode. Opts: errors=remount-ro
without multipathing
Apr 7 15:48:17 partman: mke2fs 1.42.13 (17-May-2015)
Apr 7 15:48:50 kernel: [ 413.789054] EXT4-fs (sda1): mounted filesystem with ordered data mode. Opts: errors=remount-ro
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