Re: [systemd-devel] Bug? /dev/disk/by-path symlinks disappear, for iSCSI targets
On 10/12/2014 12:00 PM, Kay Sievers k...@vrfy.org wrote: On Tue, Oct 7, 2014 at 6:21 PM, Lee Duncan ldun...@suse.com wrote: I am debugging a problem where the symlinks in /dev/disk/by-path disappeared for iSCSI target devices. It looks like it's from systemd/udev commit e98bbfd2074e2b1079b7059341eac25741baf319 udev: path_id - suppress ID_PATH for devices with an unknown parent device type I believe the worry was that if you allowed pathnames based on a parent bus that did not supply unique IDs, then you could end up with duplicate paths, since this references a bug: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1321816 But, looking at the code, this change seems to have assumed SCSI was not a supported parent. I am not aware of any cases where SCSI has given duplicate names to devices It is not about non-conflicting numbers, it is about predictability of the numbers. The SCSI enumeration numbers are not predictable and depend on enumeration or discovery order. The numbers used in by-path links would need to be able to be calculated before the device is connected. I'm not sure why you want to calculate a link before it's needed, but it seems like it certainly could be done here. The formulate for iSCSI links seems to be: ip-IP_ADDR:PORT-iscsi-IQN-iscsi-lun-LUN#-partPART# The by-path links with non-predictable numbers are pointless and wrong to create. I'm not sure what you think the by-path links are for, but they certainly aren't pointless. How do you reach that conclusion? It is expected that only a very limited subset of devices support by-path, there is nothing wrong if iSCSI does not have them. That is just not the case, and stating that it is the case doesn't make it so. There are lots of regular folks out there that use the by-path links, and no bug report that I know of ever complained of them causing any problems. Just because they fail some (arbitrary) purity test doesn't mean they are useless. While we are at it: all specialized SCSI code should move to its own package and out of the systemd/udev source tree. We will not extend any SCSI handling in udev, we just cannot support it. Hannes already started to work on moving things to sg3_utils. Hannes, any update on this? How about if we use the path_id program and drop the now-broken built-in version? Thanks, Kay No, thank you. -- Lee Duncan SUSE Labs ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Bug? /dev/disk/by-path symlinks disappear for iSCSI targets
On Tue, Oct 7, 2014 at 6:21 PM, Lee Duncan ldun...@suse.com wrote: I am debugging a problem where the symlinks in /dev/disk/by-path disappeared for iSCSI target devices. It looks like it's from systemd/udev commit e98bbfd2074e2b1079b7059341eac25741baf319 udev: path_id - suppress ID_PATH for devices with an unknown parent device type I believe the worry was that if you allowed pathnames based on a parent bus that did not supply unique IDs, then you could end up with duplicate paths, since this references a bug: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1321816 But, looking at the code, this change seems to have assumed SCSI was not a supported parent. I am not aware of any cases where SCSI has given duplicate names to devices It is not about non-conflicting numbers, it is about predictability of the numbers. The SCSI enumeration numbers are not predictable and depend on enumeration or discovery order. The numbers used in by-path links would need to be able to be calculated before the device is connected. The by-path links with non-predictable numbers are pointless and wrong to create. It is expected that only a very limited subset of devices support by-path, there is nothing wrong if iSCSI does not have them. While we are at it: all specialized SCSI code should move to its own package and out of the systemd/udev source tree. We will not extend any SCSI handling in udev, we just cannot support it. Hannes already started to work on moving things to sg3_utils. Hannes, any update on this? Thanks, Kay ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
Re: [systemd-devel] Bug? /dev/disk/by-path symlinks disappear for iSCSI targets
Ping? I will submit a patch that fixes this regression for SCSI, but I suspect other transports will have problems, too, since the by-path links will now be missing. On 10/07/2014, I wrote: Date: Tue, 07 Oct 2014 21:21:11 +0500 From: Lee Duncan ldun...@suse.com To: systemd-devel@lists.freedesktop.org Subject: [systemd-devel] Bug? /dev/disk/by-path symlinks disappear for iSCSI targets Message-ID: 543412f7.1060...@suse.com Content-Type: text/plain; charset=utf-8 Hi: I am debugging a problem where the symlinks in /dev/disk/by-path disappeared for iSCSI target devices. It looks like it's from systemd/udev commit e98bbfd2074e2b1079b7059341eac25741baf319 udev: path_id - suppress ID_PATH for devices with an unknown parent device type I believe the worry was that if you allowed pathnames based on a parent bus that did not supply unique IDs, then you could end up with duplicate paths, since this references a bug: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1321816 But, looking at the code, this change seems to have assumed SCSI was not a supported parent. I am not aware of any cases where SCSI has given duplicate names to devices Before submitting a patch to fix this for SCSI, I wanted to make sure I understood the intent correctly. Thank you for your help. -- Lee Duncan ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
[systemd-devel] Bug? /dev/disk/by-path symlinks disappear for iSCSI targets
Hi: I am debugging a problem where the symlinks in /dev/disk/by-path disappeared for iSCSI target devices. It looks like it's from systemd/udev commit e98bbfd2074e2b1079b7059341eac25741baf319 udev: path_id - suppress ID_PATH for devices with an unknown parent device type I believe the worry was that if you allowed pathnames based on a parent bus that did not supply unique IDs, then you could end up with duplicate paths, since this references a bug: https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1321816 But, looking at the code, this change seems to have assumed SCSI was not a supported parent. I am not aware of any cases where SCSI has given duplicate names to devices Before submitting a patch to fix this for SCSI, I wanted to make sure I understood the intent correctly. Thank you for your help. -- Lee Duncan ___ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
