microsoft / microsoft/diskspd

Poor 8K block performance?

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Dominant language
C++
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Description

Hello,

Is anyone else having issues with testing 1MB to 1GB file sizes with an 8K block size? Our test script shows steady performance on file sizes up to 1MB after which, IO and throughput plummets massively and then picks up again on file sizes over 500MB. When testing 4K and 256K block sizes, we see no issues. Using other tools reveals no issues with 8K, just Diskspd.

Command used: diskspd -b8K -c1M -d10 -L -o32 -Sh -t4 -r -w40 -Zr A_1M.dat B_1M.dat

Thanks

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Research direction

Start by reproducing the reported command with Diskspd across 1MB to 1GB files using 8K blocks, then compare it with the reported 4K and 256K cases. Check whether the slowdown is specific to Diskspd by comparing the other tools mentioned. Done means identifying the cause of the 8K performance drop and documenting or correcting the behavior.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
cli, performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
35/100

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