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Bug #17169

Wrong check of the limitation of creating PGs

Added by Desmond Shih over 6 years ago. Updated about 6 years ago.

Status:
Resolved
Priority:
Low
Assignee:
Category:
Monitor
Target version:
-
% Done:

0%

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

Description

When I creating PGs, I get the error msg that ceph-cli would check the number of pg created on one OSD.

Selection_055.png View (102 KB) Desmond Shih, 08/30/2016 03:25 AM

History

#1 Updated by Desmond Shih over 6 years ago

They say, in default, the limitation of number of pg created on one OSD is 32.
So, I tried some example and found out the wrong check.

I have 3 OSDs, and I have the pool 'rbd' that have 8 pgs in default.
The limitation of creating pgs should be: 3 * 32 = 96(pgs).
It should show error message when I set pg of pool more than 104(8 + 96).
But it showed error when I set to 107 but passed by 106.

#2 Updated by huang jun about 6 years ago

the code shows that:
(106-8)/3 = 32, which is not bigger than mon_osd_max_split_count(default:32);
so you can set it to 106;
but when you set to 107:
(107-8)/3 = 33, which is bigger than 32. so it reports error.

#3 Updated by Desmond Shih about 6 years ago

Hi hung jun,

There have some misunderstanding.

In a cluster which have 3 OSDs, it could create new 96(32*3) pgs at once.
So, a pool which have 8 pgs at begining grows up to 106(8 + 98) should be failed.(98 > 96)
Growing up to 104(8 + 96) should be passed.
But it pass by growing pgs to 106 in original that should be fixed.

In source code, it store the value of new pgs for each OSDs to INTEGER. It ignore the floating point that will lead to wrong result.

#4 Updated by Kefu Chai about 6 years ago

  • Status changed from New to Fix Under Review

#5 Updated by Kefu Chai about 6 years ago

  • Category changed from ceph cli to Monitor

#6 Updated by Kefu Chai about 6 years ago

  • Status changed from Fix Under Review to Resolved

technically, this change applies to hammer and jewel. but it's not critical. so i am marking it resolved.

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