Bug 1289346
Summary: | discard_zeroes_data is set to 0 in /sys for md device ; fstrim still functions | ||||||
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Product: | Red Hat Enterprise Linux 6 | Reporter: | John Pittman <jpittman> | ||||
Component: | kernel | Assignee: | Jes Sorensen <Jes.Sorensen> | ||||
kernel sub component: | Multiple Devices (MD) | QA Contact: | Zhang Yi <yizhan> | ||||
Status: | CLOSED NOTABUG | Docs Contact: | |||||
Severity: | medium | ||||||
Priority: | unspecified | CC: | xni, yizhan | ||||
Version: | 6.7 | ||||||
Target Milestone: | rc | ||||||
Target Release: | --- | ||||||
Hardware: | x86_64 | ||||||
OS: | Linux | ||||||
Whiteboard: | |||||||
Fixed In Version: | Doc Type: | Bug Fix | |||||
Doc Text: | Story Points: | --- | |||||
Clone Of: | Environment: | ||||||
Last Closed: | 2015-12-10 14:51:49 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: | |||||||
Attachments: |
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Description
John Pittman
2015-12-07 22:00:52 UTC
John, Could you elaborate on why you believe a raid5 array needs to report discard zeroes data? Whether or not data is zeroed has nothing to do with whether or not was discarded. All discard does is to tell the underlying drives that they discard of the data, and knowing it is zeroed makes it faster for the raid stack to do the resync work. The fact that an array does not zero data on discard does not imply that discard doesn't work. Jes Hi Jes, Thanks a lot for the explanation, I was not aware of that. I suppose then if the discard_zeroes_data parameter exists for the md device in /sys it should inherit or be set to the same value as the underlying disks, assuming all the underlying disks have the same discard_zeroes_data value. John John, There is no requirement for this parameter to be inherited in this case. For raid456 in particular the RAID stack has the freedom to write whatever it finds the most optimal to the device when it is being discarded. So while it might be nice for it to zero data, I don't see the current behavior being a bug. I am going to close this as notabug, if you feel this is wrong please reopen with a case for it. Thanks, Jes |