Bug 852899
| Summary: | thinp snapshots are only supported one level deep | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux 6 | Reporter: | Corey Marthaler <cmarthal> |
| Component: | lvm2 | Assignee: | Zdenek Kabelac <zkabelac> |
| Status: | CLOSED NOTABUG | QA Contact: | Cluster QE <mspqa-list> |
| Severity: | low | Docs Contact: | |
| Priority: | low | ||
| Version: | 6.3 | CC: | agk, dwysocha, heinzm, jbrassow, mcsontos, msnitzer, prajnoha, prockai, thornber, zkabelac |
| Target Milestone: | rc | ||
| Target Release: | --- | ||
| Hardware: | x86_64 | ||
| OS: | Other | ||
| Whiteboard: | |||
| Fixed In Version: | Doc Type: | Bug Fix | |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2012-10-11 08:19:05 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
Corey Marthaler
2012-08-29 22:23:54 UTC
The dm-thinp kernel code doesn't have any constraint on the depth of the snapshots of snapshots. So this is clearly an LVM constraint that needs fixing. Yes, thanks for pointing this out! It does need some changes to handle it, but it shouldn't be too tricky. To make thinbs clear: the snapshots of snapshots created here are _not_ thin-snapshots as the -L is used. IMO in this situation the thin LV should behave more like regular LV and classical snapshot should be allowed. Yes, old-style snapshots could perhaps be made to work... Good point Marian. Once I removed the '-L option' it allowed me to create many levels of snaps of snaps. I fear that this may be confusing to users if all that separates thin-snaps from regular snaps is something as simple as the "-L size" option and not some more detailed option like "--type" or something similar. POOL snapper_thinp twi-a-tz 300.00m 0.00 POOL_tdata(0) [POOL_tdata] snapper_thinp Twi-aot- 300.00m /dev/sdh1(0) [POOL_tmeta] snapper_thinp ewi-aot- 4.00m /dev/sdg1(0) origin snapper_thinp Vwi-a-tz 1.00g POOL 0.00 stack1 snapper_thinp Vwi-a-tz 1.00g POOL origin 0.00 stack10 snapper_thinp Vwi-a-tz 1.00g POOL stack9 0.00 stack11 snapper_thinp Vwi-a-tz 1.00g POOL stack10 0.00 stack12 snapper_thinp Vwi-a-tz 1.00g POOL stack11 0.00 stack2 snapper_thinp Vwi-a-tz 1.00g POOL stack1 0.00 stack3 snapper_thinp Vwi-a-tz 1.00g POOL stack2 0.00 stack4 snapper_thinp Vwi-a-tz 1.00g POOL stack3 0.00 stack5 snapper_thinp Vwi-a-tz 1.00g POOL stack4 0.00 stack6 snapper_thinp Vwi-a-tz 1.00g POOL stack5 0.00 stack7 snapper_thinp Vwi-a-tz 1.00g POOL stack6 0.00 stack8 snapper_thinp Vwi-a-tz 1.00g POOL stack7 0.00 stack9 snapper_thinp Vwi-a-tz 1.00g POOL stack8 0.00 (In reply to comment #5) > Good point Marian. Once I removed the '-L option' it allowed me to create > many levels of snaps of snaps. I fear that this may be confusing to users if > all that separates thin-snaps from regular snaps is something as simple as > the "-L size" option and not some more detailed option like "--type" or > something similar. And not only to users - you were confused as well and so was I. Also if the limits on thin snapshot sizes (whatever that means) were implemented in the future, -L would be already taken. So I'm closing this one as not a big - since for old snaps we are not supporting chaining - for thin snaps it should work. |