Bug 2140728
| Summary: | add device id type for dasd | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 9 | Reporter: | David Teigland <teigland> |
| Component: | lvm2 | Assignee: | David Teigland <teigland> |
| lvm2 sub component: | Devices, Filtering and Stacking | QA Contact: | cluster-qe <cluster-qe> |
| Status: | CLOSED MIGRATED | Docs Contact: | |
| Severity: | unspecified | ||
| Priority: | unspecified | CC: | agk, heinzm, jbrassow, msnitzer, pcahyna, prajnoha, zkabelac |
| Version: | 9.1 | Keywords: | MigratedToJIRA, Triaged |
| Target Milestone: | rc | Flags: | pm-rhel:
mirror+
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| Target Release: | --- | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2023-09-23 18:35:57 UTC | Type: | Bug |
| Regression: | --- | Mount Type: | --- |
| Documentation: | --- | CRM: | |
| Verified Versions: | Category: | --- | |
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |
| Cloudforms Team: | --- | Target Upstream Version: | |
| Embargoed: | |||
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Description
David Teigland
2022-11-07 18:53:38 UTC
patch that needs to be verified on a system with dasd devices https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=e149a81be491f440ba0cce2a1a076a35aa5219be I found this documentation about DASD attributes: https://www.ibm.com/docs/en/linux-on-systems?topic=dasds-dasd-information The relevant part is: uid A device identifier of the form <vendor>.<serial>.<subsystem_id>.<unit_address>.<minidisk_identifier> where <vendor> is the specification from the vendor attribute. <serial> is the serial number of the storage system. <subsystem_id> is the ID of the logical subsystem to which the DASD belongs on the storage system. <unit_address> is the address that is used within the storage system to identify the DASD. <minidisk_identifier> is an identifier that the z/VM® system assigns to distinguish between minidisks on the DASD. This part of the uid is only present for Linux on z/VM and if the z/VM version and service level support this identifier. This attribute is read-only. Thanks, AFAICS lvm won't need to parse the string components but just copy the entire thing as the device id. Are you able to test the patch in comment 1? Hi Pavel, will you be able to test the patch in comment 1? (In reply to David Teigland from comment #4) > Hi Pavel, will you be able to test the patch in comment 1? Hi David, I could test the patch, but I am not convinced anymore that adding this feature is right, because I am not sure how stable this identifier really is in practice (I am not familiar in detail with S/390). Sure, in normal operation the ID will remain the same, but what if the administrator decides to copy the VM data to another storage system (one of the components of the ID is "the serial number of the storage system"). Won't they expect that the VMs will work as before? This expectation would be broken by the proposed change. I am afraid that the change thus has a potential to generate more support cases / bug reports. Is there a drawback with the current situation having block devices that do not have IDs known to LVM? Performance impact when LVM has to scan all the devices for metadata instead of only the right ones? (I admit I am biased, because the devices file in general seems like a misfeature to me, the concerns above can apply also for other disk types.) We want the device id to act like a traditional WWID, and identify only the storage, not the host in any way. i.e. the device id shouldn't change if the storage is moved to another system. If the dasd id you described in comment 2 contains any host-specific field, then we could remove that component when generating the lvm device id. (In reply to Pavel Cahyna from comment #5) > Is there a drawback with the current situation having > block devices that do not have IDs known to LVM? Performance impact when LVM > has to scan all the devices for metadata instead of only the right ones? Yes, that's one issue. In addition the lvm device id resolves problems when lvm PVs are cloned/copied and lvm doesn't know which one is correct, or problems where multipath component devices can be mistaken for the multipath device itself. (In reply to David Teigland from comment #7) > In addition the lvm device id resolves problems when > lvm PVs are cloned/copied and lvm doesn't know which one is correct, or > problems where multipath component devices can be mistaken for the multipath > device itself. Sorry, those are just advantages compared to no device id at all. The only real issue with using devname device id is more device scanning when device names change. Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug. This BZ has been automatically migrated to the issues.redhat.com Red Hat Issue Tracker. All future work related to this report will be managed there. Due to differences in account names between systems, some fields were not replicated. Be sure to add yourself to Jira issue's "Watchers" field to continue receiving updates and add others to the "Need Info From" field to continue requesting information. To find the migrated issue, look in the "Links" section for a direct link to the new issue location. The issue key will have an icon of 2 footprints next to it, and begin with "RHEL-" followed by an integer. You can also find this issue by visiting https://issues.redhat.com/issues/?jql= and searching the "Bugzilla Bug" field for this BZ's number, e.g. a search like: "Bugzilla Bug" = 1234567 In the event you have trouble locating or viewing this issue, you can file an issue by sending mail to rh-issues. You can also visit https://access.redhat.com/articles/7032570 for general account information. |