Bug 1860720
| Summary: | RFE: kickstart option to control discard configuration | ||
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| Product: | [Fedora] Fedora | Reporter: | Chris Murphy <bugzilla> |
| Component: | anaconda | Assignee: | Anaconda Maintenance Team <anaconda-maint-list> |
| Status: | CLOSED DEFERRED | QA Contact: | Fedora Extras Quality Assurance <extras-qa> |
| Severity: | unspecified | Docs Contact: | |
| Priority: | unspecified | ||
| Version: | rawhide | CC: | anaconda-maint-list, butirsky, davide, ego.cordatus, jkonecny, jonathan, kellin, mcatanza, mkletzan, vanmeeuwen+fedora, vponcova, wwoods |
| Target Milestone: | --- | ||
| 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: | 2020-08-20 04:30:11 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: | |||
| Bug Depends On: | |||
| Bug Blocks: | 1851166 | ||
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Description
Chris Murphy
2020-07-26 21:34:07 UTC
Arguably --discards=default doesn't need to exist, but I'm not sure of the style/semantics. If it's not needed, great. Another possibility is some kind of condition check that chooses on/off. This would mean the installer can just figure it out. e.g. --discard=auto If the condition check sees both SSD and not a virtual machine guest, then discard=on. Otherwise, discard=default (or possibly discard=off). I think the '--fsoptions FSOPTS' argument for part should work fine for this: https://pykickstart.readthedocs.io/en/latest/kickstart-docs.html#part-or-partition I'd really like to try to avoid piling on more options unless they are absolutely needed. Understood. Is it possible in kickstart to test for some condition, so that the option is used only for those conditions? i.e. only if the file system is btrfs, not if it's in a VM, not if the target is rotational (or other test that discards are supported). I think those three are everything. (In reply to Chris Murphy from comment #4) > Understood. Is it possible in kickstart to test for some condition, so that > the option is used only for those conditions? i.e. only if the file system > is btrfs, not if it's in a VM, not if the target is rotational (or other > test that discards are supported). I think those three are everything. No, and that's not something that we'll be adding :) The way people usually handle that is via %pre scripts and %include but even then that's a bit of a hack. As written in comment 0, this would really span anaconda, pykickstart, and python-blivet. Taking only a subset of the RFE, Brian says that from pykickstart point of view, there is already a way to provide the raw fstab options string. The kickstart would look something like this: > part (...) --fsoptions "discard=async" But with conditional enablement, the scope expands: The right place to decide if the option would be set is the blivet library which handles actual storage manipulation. And of course anaconda would have to glue that with the rest of the works. I wonder if it's possible, and more appropriate, to do this by udev rule injecting the mount option? It would be much less discoverable to the user, but I'm not convinced it's a significant negative *if* the condition checking is reliable, and the applied policy is correct. We have similar problems elsewhere, e.g. "rotational" detection is not reliable. USB sticks report they're rotational, as do virtioblk (/dev/vda) devices. I would argue for not making this behave differently based on whether the host is a VM or not. Not only can it make some future reproducers difficult, but the hypervisor itself should be intelligent enough to only enable the discards to go through when it wants to (e.g. thin provisioning), but not for fully allocated disks. (In reply to Martin Kletzander from comment #8) > the hypervisor itself should be intelligent enough to only > enable the discards to go through when it wants to It's a persuasive argument. Also, for reference: https://www.redhat.com/archives/libvir-list/2020-August/msg00341.html Consolidating btrfs issues for design and planning logics. This issue is now found here: #6 enable discard=async by default https://pagure.io/fedora-btrfs/project/issue/6 |