counters for misaligned (partial?) writes

evilensky — Thu, 05 Jun 2025 07:29:55 GMT

Greetings,

What are the best-practice counters for monitoring misaligned, partial writes, specifically due to misaligned VMware virtual machines? The best-practice TR states that if performance is not an issue, aligning existing virtual machines may be more trouble than specifically worth.

Is there any way to guesstimate the performance delta between our specific, misaligned environment and a hypothetical, properly-aligned one? That is, I would like to know how much of a hit the storage system is taking due to the mis-alignment, even if our users are not experiencing issues.

Thanks,

Eugene

Re: counters for misaligned (partial?) writes

chriskranz — Fri, 13 Mar 2009 07:55:15 GMT

If you go into "priv set diag" (warning: be careful!), you can run the stats command to show the misaligned block counts...

filer01*> stats list counters LUN
Counters for object name: LUN
        read_ops
        write_ops
        other_ops
        read_data
        write_data
        queue_full
        avg_latency
        total_ops
        scsi_partner_ops
        scsi_partner_data
        read_align_histo
        write_align_histo
        read_partial_blocks
        write_partial_blocks

This won't specifically tell you the performance overhead and hit you are having due to this, but it'll give you an idea of how much of your data is getting effected by misalignment.

topic counters for misaligned (partial?) writes in VMware Solutions Discussions

counters for misaligned (partial?) writes

Re: counters for misaligned (partial?) writes