PAGEIOLATCH_NL is the Null (NL) mode member of the I/O page latch family, a placeholder so every latch mode has a PAGEIOLATCH_* counterpart. Null mode acquires nothing, and this wait type goes unused in practice.
Its siblings do the family’s real work: PAGEIOLATCH_SH for pages being read from disk, PAGEIOLATCH_EX and PAGEIOLATCH_UP for write-side I/O latching.
Is It a Problem?
No, and a non-zero value would itself be the anomaly. When I/O latching genuinely hurts, the evidence arrives through the working modes with high average durations, and the diagnosis runs through storage latency (sys.dm_io_virtual_file_stats), buffer pool health, and the queries driving reads.
Nothing about that investigation ever involves this placeholder.
Common Causes
- None; the mode is unused.
What To Do
- Nothing here. The
PAGEIOLATCH_SHdeep dive covers the family’s real diagnostics.
How To See It
Rank waits with Get-WaitStatistics; this entry stays at zero.
PAGEIOLATCH_NL is background noise on a healthy instance. If you are chasing a real problem, start with the waits that actually cost you time.
- The waits that usually matter, ranked, with what each one is telling you.
- PAGEIOLATCH_SH Wait Type, the closest wait worth investigating when this one is high.
- Storage & Capacity, the scripts and guides for this part of the stack.
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