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check_for_optimal_dd_blocksize

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check_for_optimal_dd_blocksize [2018/07/05 10:50]
admin created
check_for_optimal_dd_blocksize [2018/07/05 10:50] (current)
admin
Line 1: Line 1:
 +<code>
 +#!/bin/bash
 +
 +# Since we're dealing with dd, abort if any errors occur
 +set -e
 +
 +TEST_FILE=${1:-dd_obs_testfile}
 +[ -e "$TEST_FILE" ]; TEST_FILE_EXISTS=$?
 +TEST_FILE_SIZE=134217728
 +
 +# Header
 +PRINTF_FORMAT="%8s : %s\n"
 +printf "$PRINTF_FORMAT" 'block size' 'transfer rate'
 +
 +# Block sizes of 512b 1K 2K 4K 8K 16K 32K 64K 128K 256K 512K 1M 2M 4M 8M 16M 32M 64M
 +for BLOCK_SIZE in 512 1024 2048 4096 8192 16384 32768 65536 131072 262144 524288 1048576 2097152 4194304 8388608 16777216 33554432 67108864
 +do
 +  # Calculate number of segments required to copy
 +  COUNT=$(($TEST_FILE_SIZE / $BLOCK_SIZE))
 +
 +  if [ $COUNT -le 0 ]; then
 +    echo "Block size of $BLOCK_SIZE estimated to require $COUNT blocks, aborting further tests."
 +    break
 +  fi
 +
 +  # Create a test file with the specified block size
 +  DD_RESULT=$(dd if=/dev/zero of=$TEST_FILE bs=$BLOCK_SIZE count=$COUNT 2>&1 1>/dev/null)
 +
 +  # Extract the transfer rate from dd's STDERR output
 +  TRANSFER_RATE=$(echo $DD_RESULT | \grep --only-matching -E '[0-9.]+ ([MGk]?B|bytes)/s(ec)?')
 +
 +  # Clean up the test file if we created one
 +  [ $TEST_FILE_EXISTS -ne 0 ] && rm $TEST_FILE
 +
 +  # Output the result
 +  printf "$PRINTF_FORMAT" "$BLOCK_SIZE" "$TRANSFER_RATE"
 +done
 +
 +</code>
 +
 credits go to: [[http://blog.tdg5.com/tuning-dd-block-size/]] credits go to: [[http://blog.tdg5.com/tuning-dd-block-size/]]
check_for_optimal_dd_blocksize.txt ยท Last modified: 2018/07/05 10:50 by admin