1SPEW(1) User Commands SPEW(1)
2
6 spew - measures I/O performance and/or generates I/O load
7
9 spew --write|--read|--read-after-write [OPTION]... TRANSFER_SIZE[kKm‐
10 MgG] FILE
11
13 An I/O performance measurement and load generation tool. Writes and/or
14 reads generated data to or from a character device, block device, or
15 regular file.
16 -B, --max-buffer-size=BUFFER_SIZE
18 Each read(2)/write(2) call uses a maximum buffer of size BUF‐
19 FER_SIZE.
20 -b, --min-buffer-size=BUFFER_SIZE
22 Each read(2)/write(2) call uses a minimum buffer of size BUF‐
23 FER_SIZE.
24 -c, --continue-after-error
26 Continue after data integrity errors.
27 -d, --direct
29 Use direct I/O. Should only be used on block device files. Not
30 all operating systems support direct I/O
31 -g, --generate-load
33 Equivalent to: -v -t -P -p random -i 0.
34 -i, --iterations=COUNT
36 Write/read data COUNT times. If count is 0, repeats forever.
37 -l, --logfile=LOGFILE
39 Send log messages to LOGFILE.
40 --no-progress
42 Don't show progress (default).
43 --no-rcfiles
45 Don't use standard rcfiles.
46 -q, --no-statistics
48 Don't output statistics.
49 --no-tui
51 Don't use TUI interface.
52 -o, --offset=OFFSET
54 Seek to OFFSET before starting I/O.
55 -P, --progress
57 Show progress.
58 -p, --pattern=PATTERN
60 Use data pattern PATTERN when reading or writing data.
61 -r, --random
63 Read/Write buffers to random offsets.
64 --raw An alias for --read-after-write.
66 --rcfile=RCFILE
68 Read command-line options from RCFILE.
69 --read Read date from FILE.
71 --read-after-write
73 Read back data after writing to FILE.
74 -S, --seed=SEED
76 Use SEED for random number seed.
77 -s, --sync
79 Use synchronous I/O.
80 --statistics
82 Output statistics (default).
83 -t, --tui
85 Use curses-based, terminal user interface.
86 -u, --units=UNITS
88 Show transfer rate in UNITS units.
89 --usage
91 Show brief usage message and exit.
92 -V, --version
94 Output version information and exit.
95 -v, --detailed-statistics
97 Output detailed statistics.
98 --write
100 Write data to FILE.
101 -?, --help
103 Show this help and exit.
104 FILE Regular or device file to write data to.
106 LOGFILE
108 Path to a file used for logging.
109 MAX_BUFFER_SIZE
111 Minimum buffer size used in each read(2)/write(2) call (default
112 is MIN_BUFFER_SIZE bytes). MAX_BUFFER_SIZE. Must be an even
113 multiple of 512 bytes and can be specified in bytes,
114 kibibytes(k), kilobytes(K), mebibytes(m), megabytes(M),
115 gibibytes(g), gigabytes(G). tebibytes(t), or terabytes(T).
116 MAX_BUFFER_SIZE defaults to MIN_BUFFER_SIZE. If MAX_BUFFER_SIZE
117 > MIN_BUFFER_SIZE, random buffers sizes between the two limits
118 are used. MAX_BUFFER_SIZE must be an even multiple of MIN_BUF‐
119 FER_SIZE.
120 MIN_BUFFER_SIZE
122 Minimum buffer size used in each read(2)/write(2) call (default
123 is 512 bytes). MIN_BUFFER_SIZE. Must be an even multiple of 512
124 bytes and can be specified in bytes, kibibytes(k), kilobytes(K),
125 mebibytes(m), megabytes(M), gibibytes(g), gigabytes(G).
126 tebibytes(t), or terabytes(T).
127 OFFSET Position to seek to in the file before starting I/O (default is
129 0). OFFSET must be an even multiple of 512 bytes and can be
130 specified in bytes, kibibytes(k), kilobytes(K), mebibytes(m),
131 megabytes(M), gibibytes(g), gigabytes(G). tebibytes(t), or ter‐
132 abytes(T).
133 PATTERN
135 Data pattern used when writing/reading data. Available patterns
136 are: none, zeros, ones, alt, random, numbers, and "#" (where "#"
137 is a number between 0-255). The default pattern is "none".
138 RCFILE Read additional command-line options from RCFILE. Other options
140 on the command-line will override options in RCFILE.
141 SEED Used to seed the random number generator Must be >= 1 and <=
143 2^32.
144 TRANSFER_SIZE
146 Total number of bytes to transfer (must be an even multiple of
147 both MIN_BUFFER_SIZE and MAX_BUFFER)SIZE). TRANSFER_SIZE can be
148 specified in bytes, kilobytes, megabytes, or gigabytes.
149 UNITS Kibibytes(k), kilobytes(K), mebibytes(m), megabytes(M),
151 gibibytes(g), gigabytes(G). tebibytes(t), or terabytes(T).
152
154 spew --write -b 16k 1m /tmp/bigfile
155 or
157 spew -b 16k 1m /tmp/bigfile
159 Writes 1 mebibyte (1 mebibyte = 1024*1024 bytes) using 16 kibibytes (1
161 kibibyte = 1024 bytes) requests to the file /tmp/bigfile using the
162 default pattern (random). Displays the write transfer rate in
163 kibibytes per second and the write transfer time in seconds.
164 spew --write -u m -i 10 -b 1k 256k /dev/sda1
166 or
168 spew -u m -i 10 -b 1k 256k /dev/sda1
170 Writes 256 kibibytes using 1 kibibyte requests to the block device file
172 /dev/sda1 10 times using the default pattern (random). The iteration
173 and cumulative write transfer rates are displayed in mebibytes per sec‐
174 ond and the iteration and cumulative write transfer times are displayed
175 in seconds.
176 spew --raw -d -o 1m -b 16m 1g /tmp/bigfile
178 or
180 regorge -s -o 1m -b 16m 1g /tmp/bigfile
182 Write 1 gibibyte (1 gibibyte = 1024*1024*1024 bytes) starting at an
184 offset of 1 mebibyte using 16 mebibyte requests to the file /tmp/big‐
185 file using the default pattern (random). The data is written syn‐
186 chronously and flushed at file close. Then read in the same data using
187 the same request size and offset. The data is checked to ensure that
188 the data read in matches the data read out. Write and read tranfer
189 rates are displayed in kibibytes/second. Read are write transfer times
190 are displayed in seconds.
191 spew --read -i 0 -u M -p zeros -b 512 1m /dev/zero
193 or
195 gorge -i 0 -u M -p zeros -b 512 1m /dev/zero
197 Read 1 mebibyte of data using 512 byte requests from the file /dev/zero
199 an infinite number of times using the zeros pattern (don't check the
200 data). The iteration and cumulative read transfer rates are displayed
201 in megabytes (1 megabyte = 1,000,000 bytes) per second and the itera‐
202 tion and cumulative read transfer times are displayed in seconds.
203 spew --raw -g -r -b 1k -B 256K 1t /dev/md1
205 or
207 regorge -g -r -b 1k -B 256K 1t /dev/md1
209 Write 1 tebibyte (1 tebibyte = 1024*1024*1024*1024 bytes) using 1-256
211 kibibyte requests to the block device /dev/md1 using the random pat‐
212 tern. Random seeks are performed before each transfer, but each block
213 between the start and end of the data is written exactly once. The
214 request sizes are chosen randomly. Then read in the same data using
215 the same request sizes and seeks in the same sequence. Repeat the
216 above sequence an infinite number of times until told to quit (via sig‐
217 nal or TUI command).
218 The data is checked to ensure that the data read in matches the data
220 read out. A curses-based TUI is used to display iteration and cumula‐
221 tive transfer rates, transfer times, and bytes transferred. Display
222 verbose statistics after quitting.
223
225 The following algorithm is used to determine blocksize when MAX_BUF‐
226 FER_SIZE > MIN_BUFFER_SIZE:
227 Find the largest blocksize that is a power of 2 and is >= MAX_BUF‐
229 FER_SIZE. Call this maxbuffersize. Find the smallest buffersize that
230 is a power of 2 and is >= MIN_BUFFER_SIZE. Call this minbuffersize.
231 Chunksize = maxbuffersize * (difference in number of bits between min
232 and maxbuffersize + 1). The number of chunks is TRANSFER_SIZE/chunk‐
233 size. Call this numchunks. There will be numchunks number of
234 read/writes that are of size maxbuffersize, 2 * numchunks number of
235 read/writes that are of size maxbuffersize/2, 4 * numchunks number of
236 read/writes that are of size maxbuffersize/4, and so on until min‐
237 buffersize is reached. MIN_BUFFER_SIZE is used for any remaining
238 transfers if TRANSFER_SIZE is not evenly divisible by chunksize.
239 Example: Using a MIN_BLOCK_SIZE of 1k, a MAX_BLOCK_SIZE of 8k and a
241 TRANSFER_SIZE of 264k results in 8 8k read/writes, 16 4k read/write, 32
242 2k read/writes, and 64 + 8 1k read/writes.
243
245 Use the following od(1) command to examine spew generated files where a
246 data integrity problem has occurred:
247 od -A d --format=d8 --width=32 <file>
249
251 $HOME/.spewrc or $SPEWRC
252 Holds user default options. These options precede any options
253 included on the command-line.
254 /etc/spew.conf
256 Holds system-wide default options. These options precede any
257 options included on the command-line and options included from
258 $HOME/.spewrc or $SPEWRC.
259
261 Written by Andrew Patterson <andrew.patterson@hp.com>
262
264 Report bugs to Andrew Patterson <andrew.patterson@hp.com>.
265 Copyright 2007 Hewlett-Packard Corp.
267spew 1.0.8 May 2010 SPEW(1)