---
name: "bitesize.d"
section: "1m"
platform: "macos"
package: "dtrace"
version: "413"
release: "macOS 26.5"
platforms: ["macos"]
url: "https://new.carta.tech/bitesize.d"
---

# bitesize.d(1m)

analyse disk I/O size by process. Uses DTrace.

## NAME

bitesize.d - analyse disk I/O size by process. Uses DTrace.

## SYNOPSIS

**bitesize.d**

## DESCRIPTION

This produces a report for the size of disk events caused by processes. These are the disk events sent by the block I/O driver.

If applications must use the disks, we generally prefer they do so sequentially with large I/O sizes, or larger "bites".

Since this uses DTrace, only users with root privileges can run this command.

## EXAMPLES

- Sample until Ctrl-C is hit then print report,

  \#  **bitesize.d**

## FIELDS

- PID

  process ID

- CMD

  command and argument list

- value

  size in bytes

- count

  number of I/O operations

## NOTES

The application may be requesting smaller sized operations, which are being rounded up to the nearest sector size or UFS block size.

To analyse what the application is requesting, DTraceToolkit programs such as Proc/fddist may help.

## DOCUMENTATION

See the DTraceToolkit for further documentation under the  Docs directory. The DTraceToolkit docs may include full worked examples with verbose descriptions explaining the output.

## EXIT

bitesize.d will sample until Ctrl-C is hit.

## AUTHOR

Brendan Gregg \[Sydney, Australia\]

## SEE ALSO

iosnoop(1M), seeksize(1M), dtrace(1M)