Bug 1464739 - Cache & thin pool target always commits data even for unused devices
Summary: Cache & thin pool target always commits data even for unused devices
Keywords:
Status: NEW
Alias: None
Product: LVM and device-mapper
Classification: Community
Component: device-mapper
Version: 2.02.172
Hardware: Unspecified
OS: Unspecified
low
unspecified
Target Milestone: ---
: ---
Assignee: Joe Thornber
QA Contact: cluster-qe
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2017-06-25 09:39 UTC by Zdenek Kabelac
Modified: 2023-08-10 15:41 UTC (History)
6 users (show)

Fixed In Version:
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Embargoed:
rule-engine: lvm-technical-solution?

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Description Zdenek Kabelac 2017-06-25 09:39:53 UTC 
Description of problem:

When user creates thin-pool with unused  thin LV, or  caches a volume, then every call a flushing  'dmsetup status' cause  very small i/o batch to pass on actual real device.

This is not a big deal in case performance, but it prevents unused 'devices' to stay in sleep eventually wakes them up whenever admin runs: 

dmsetup status.

As a workaround to keep disks sleeping - user may 'add --noflush' arg...



Version-Release number of selected component (if applicable):
4.12.0-0.rc6.git3.2.fc27.x86_64

How reproducible:


Steps to Reproduce:
1. create  thinLV  (lvcreate -L10 -V10 -T vg/pool -n thinLV)  (or cache some LV)
2. iostat -d 1
3. observe i/o load with every 'dmsetup status' call

Actual results:


Expected results:


Additional info:
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