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ZFS Write Performance Degrades With Threads Held Up By space_map_load_wait() (Doc ID 1359269.1)

Last updated on FEBRUARY 01, 2019

Applies to:

Sun Storage 7720 Unified Storage System - Version Not Applicable and later
Sun ZFS Storage 7420 - Version Not Applicable and later
Sun Storage 7310 Unified Storage System - Version Not Applicable and later
OpenSolaris Operating System - Version 2008.05 and later
Sun Storage 7110 Unified Storage System - Version Not Applicable and later
Information in this document applies to any platform.
***Checked for relevance on 26-Aug-2013***

Symptoms

There are several actions required to confirm this issue. 

A threadlist taken from the system during the performance issue should contain threads with a stack similar to the following:



Changes

This issue can occur in situations where additional top-level vdevs have been added to an existing zpool to increase storage.  This results in imbalanced vdevs within the zpool where the original vdevs have more data on them than the new ones.  When the older vdevs fill up ZFS will spend a lot of time in space_map_load_wait() trying to look for space in other vdevs.

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References

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