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I am puzzled about Iozone record sizes. My questions are:

  • how to find out what record size my application uses?;
  • what is the correlation between Iozone record size and the filesystem Block Size?;
  • how I can tune my filesystem (ext4) to benefit from certain record size?;

Thanks!

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1 Answer

I think the IOzone term,record size, is similar to avgrq-sz

avgrq-sz: The average size (in 512 Byte sectors) of the requests that were issued to the device.

how to find out what record size my application uses?;

$iostat -x /dev/sdc

Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sdc 1.96 1.68 1.33 0.54 274.67 273.13 293.56 0.02 8.61 0.90 0.17

what is the correlation between Iozone record size and the filesystem Block Size?;

I think, when determining block size, just make sure it is 1/n of record size

how I can tune my filesystem (ext4) to benefit from certain record size?;

same as above.

In terms of file system peformance, another factor need to be considered, if you use RAID. It is chunk size of raid device

Chunk Size=avgrq-sz/ number of data disks

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