Bug 1227503 - /dev/disk/by-id/wwn-* links for SATA devices have words in reverse order [NEEDINFO]
Summary: /dev/disk/by-id/wwn-* links for SATA devices have words in reverse order
Alias: None
Product: Fedora
Classification: Fedora
Component: systemd
Version: 23
Hardware: x86_64
OS: Linux
Target Milestone: ---
Assignee: systemd-maint
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2015-06-02 20:07 UTC by Uwe Menges
Modified: 2016-12-20 13:44 UTC (History)
11 users (show)

Fixed In Version: systemd-219-20.fc22
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2016-12-20 13:44:04 UTC
nkshirsa: needinfo?

Attachments (Terms of Use)

Description Uwe Menges 2015-06-02 20:07:20 UTC
Description of problem:
The /dev/disk/by-id/wwn-* links are wrong for SATA devices, and have changed from F21 to F22, therefore rendering these presumably "persistent" links pretty much useless across updates. The fact that WWN are explicitly taken as persistent and stable, also across platforms, and now have changed from one distro version to another, qualifies for severity high in my opinion.

Version-Release number of selected component (if applicable):

How reproducible: always
Check the WWN of a SATA device:
# hdparm -I /dev/sda | grep WWN
Logical Unit WWN Device Identifier: 50014ee2602c6589

Steps to Reproduce:
1. Use F22 with systemd-219-15.fc22.x86_64
2. Check the WWN of a SATA device with hdparm -I
3. Check the link(s) in /dev/disk/by-id/wwn-*

Actual results:
Actual link created for WWN 50014ee2602c6589:

Expected results:
Expected link: /dev/disk/by-id/wwn-0x50014ee2602c6589

Additional info:
Worked as expected with F21, changed behaviour with F22.

The /dev/disk/by-id/wwn-* link apparently has no relation, or none I could obviously see, to the WWN reported by hdparm -I, or any other string reported by hdparm or other tools like smartctl -a:
# smartctl -a /dev/sda  | grep WWN
LU WWN Device Id: 5 0014ee 2602c6589

Nevertheless, udevadm info gives the wrong WWN, and absolutely no value containing the correct WWN:
# udevadm info -p /sys/class/block/sda | grep -E '7316484813058363393|50014ee2602c6589'
S: disk/by-id/wwn-0x7316484813058363393x
E: DEVLINKS=/dev/disk/by-id/ata-WDC_WD50EZRX-00MVLB1_WD-WXC1H3443687 /dev/disk/by-id/wwn-0x7316484813058363393x
E: ID_WWN=0x7316484813058363393x
E: ID_WWN_WITH_EXTENSION=0x7316484813058363393x

Comment 1 Uwe Menges 2015-06-19 21:59:59 UTC
I think I found the relation:


Decimal 7316484813058363393
is hex  6589 602C 4EE2 5001

WWN is  5001 4ee2 602c 6589

So this seems to be some formatting error, and the additional 'x' at the end is maybe also a leftover from that.

Comment 2 Uwe Menges 2015-06-19 22:52:45 UTC
I think this commit is the culprit:

$ git diff 6024a6e302bad6bcf073fa84a41a6123305dc845 11c6f693e94e9013c8df91210b8b0e2e343de809 ata_id.c | nl

   111  -                if ((word & 0xf000) == 0x5000) {
   112  -                        uint64_t wwwn;
   113  -
   114  -                        wwwn = identify.octa[108/4];
   115  -                        printf("ID_WWN=0x%llx\n", (unsigned long long int) wwwn);
   116  -                        /* ATA devices have no vendor extension */
   117  -                        printf("ID_WWN_WITH_EXTENSION=0x%llx\n", (unsigned long long int) wwwn);
   118  -                }
   119  +                if ((word & 0xf000) == 0x5000)
   120  +                        printf("ID_WWN=0x%1$"PRIu64"x\n"
   121  +                               "ID_WWN_WITH_EXTENSION=0x%1$"PRIu64"x\n",
   122  +                               identify.octa[108/4]);

Comment 3 Uwe Menges 2015-06-23 23:31:15 UTC
FWIW, here's the scsi_id output:

# /usr/lib/udev/scsi_id -g -x /dev/sda

Comment 5 Kay Sievers 2015-06-24 00:29:29 UTC
Merged upstream.

Comment 6 Piergiorgio Sartor 2015-06-29 17:48:26 UTC
This bug seems to be duplicate of #1214305.

Maybe one of the two should be marked properly.




Comment 7 Zbigniew Jędrzejewski-Szmek 2015-07-21 20:12:32 UTC

*** This bug has been marked as a duplicate of bug 1214305 ***

Comment 8 Uwe Menges 2015-07-21 20:24:41 UTC
Unfortunately this fix (included in systemd-219-19.fc22.x86_64) doesn't do it.
It now prints the hex numbers, but the words are swapped:

# /usr/lib/udev/scsi_id -g -x /dev/sda | grep WWN

Actual output:
# udevadm info -p /sys/class/block/sda | grep WWN
E: ID_WWN=0x6589602c4ee25001
E: ID_WWN_WITH_EXTENSION=0x6589602c4ee25001

Comment 9 Zbigniew Jędrzejewski-Szmek 2015-07-22 04:29:36 UTC

Pfff, I'm not sure what to do about backwards compatibility. Bad formatting was introduced in systemd-219, i.e. it has been bad for the whole life of F22. One option would be to assume that anyone to be bitten by this already changed to use a different link. Another option would be to provide a backwards compatible link under the broken name (with "x") at the end, since this is the link used during installation. I'm leaning towards the second option.

Comment 10 Zbigniew Jędrzejewski-Szmek 2015-07-22 04:38:45 UTC
And the temporary hack would look like this: https://github.com/keszybz/systemd/commit/c505b456a6b23ffe1d11b597f4aa82f5bead961f. Hopefully this would minimize breakage of existing installations.

Comment 11 Fedora Update System 2015-07-27 16:34:48 UTC
systemd-219-20.fc22 has been submitted as an update for Fedora 22.

Comment 12 Fedora Update System 2015-07-30 01:11:40 UTC
Package systemd-219-20.fc22:
* should fix your issue,
* was pushed to the Fedora 22 testing repository,
* should be available at your local mirror within two days.
Update it with:
# su -c 'yum update --enablerepo=updates-testing systemd-219-20.fc22'
as soon as you are able to.
Please go to the following url:
then log in and leave karma (feedback).

Comment 13 Fedora Update System 2015-08-01 02:25:04 UTC
systemd-219-20.fc22 has been pushed to the Fedora 22 stable repository.  If problems still persist, please make note of it in this bug report.

Comment 14 Uwe Menges 2015-12-15 22:17:07 UTC
I updated to F23, and it seems the issue with the swapped hex parts reappeared, I get the same output as in #c8.


Comment 15 Uwe Menges 2016-01-31 13:25:41 UTC
Is it a problem to push the existing fix for F22 to current F23?
I'm at systemd-222-13.fc23.x86_64 now, where the issue still exists.

Comment 16 Lennart Poettering 2016-02-10 14:21:04 UTC
Fixed in cf22cddcfd07d10fecd7b03ef465e957054daec2 upstream a while back.

Comment 17 Peter Steele 2016-02-11 16:43:03 UTC
We've just hit this ourselves in RHEL 7.2 (kernel 3.10.0-327.4.5.el7.x86_64). This blocks us from moving to this release since we use the drive wwn numbers and assume they will never change. When do we expect to see this fixed in RHEL?

Comment 18 Michal Sekletar 2016-02-11 18:00:18 UTC
(In reply to Peter Steele from comment #17)
> We've just hit this ourselves in RHEL 7.2 (kernel
> 3.10.0-327.4.5.el7.x86_64). This blocks us from moving to this release since
> we use the drive wwn numbers and assume they will never change. When do we
> expect to see this fixed in RHEL?

We have scheduled this fix to land in RHEL-7.3. But we can certainly deliver sooner. AFAICT, next 7.2 z-stream batch is planned to be released at the end of the March. In order to get that fix into z-stream you have to escalate via your support representative.

Comment 19 Peter Steele 2016-02-12 18:58:19 UTC
Okay, I'll investigate doing that...

Comment 21 Mike McCune 2016-03-28 23:38:32 UTC
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see mmccune@redhat.com with any questions

Comment 22 Fedora End Of Life 2016-11-24 11:51:09 UTC
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