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Bug #23554

mon: mons need to be aware of VDO statistics

Added by David Galloway almost 6 years ago. Updated almost 6 years ago.

Status:
New
Priority:
Normal
Assignee:
-
Category:
-
Target version:
-
% Done:

0%

Source:
Development
Tags:
Backport:
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(RADOS):
Monitor
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

I created an OSD on top of a logical volume with a VDO device underneath.

Ceph is unaware of how much compression and deduplication has been done.

[root@reesi003 ~]# ceph osd df | grep 'ID\|^55'
ID CLASS WEIGHT  REWEIGHT SIZE  USE    AVAIL  %USE  VAR  PGS 
55   hdd 3.65810  1.00000 3745G 55080M  3692G  1.44 0.06 367 

[root@reesi004 ~]# vdostats --hu
Device                    Size      Used Available Use% Space saving%
/dev/mapper/vdo_sda       3.6T     25.1G      3.6T   0%           21%

Note the space saving percentage is incorrect. I filed https://bugzilla.redhat.com/show_bug.cgi?id=1563794 for that.

Steps to reproduce:

vdo create --name vdo_sda --device=/dev/sda --writePolicy=async

pvcreate /dev/mapper/vdo_sda

vgcreate vg_sda /dev/mapper/vdo_sda

lvcreate -l 100%FREE -n lv_sda vg_sda

ceph-volume lvm create --bluestore --data vg_sda/lv_sda --block.db journals/sda

History

#1 Updated by Greg Farnum almost 6 years ago

What would we expect this monitor awareness to look like? Extra columns duplicating the output of vdostats?

#3 Updated by David Galloway almost 6 years ago

Of course Sage is already on it :)

I don't know where the osd df output is read from but my non-developer mind assumes the OSD process could run vdostats and report back how much actual space is being used.

Based on what I'm actually able to decipher in Sage's PR, that's what's being done.

#4 Updated by Greg Farnum almost 6 years ago

Right, but AFAICT the monitor is then not even aware of VDO being involved. Which seems fine to my naive thoughts, but might be an issue in terms of either "advertising" or accurate trend monitoring.

#5 Updated by Patrick Donnelly almost 6 years ago

  • Subject changed from MONs need to be aware of VDO statistics to mon: mons need to be aware of VDO statistics
  • Source set to Development

#6 Updated by Patrick Donnelly almost 6 years ago

  • Project changed from Ceph to RADOS

#7 Updated by Patrick Donnelly almost 6 years ago

  • Component(RADOS) Monitor added

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