Provided by: stressant_0.6.0_all 
NAME
stressant - Stressant Documentation
SYNOPSIS
stressant [-h] [–version] [–logfile PATH] [–email EMAIL] [–smtpserver HOST] [–smtpuser
USERNAME] [–smtppass PASSWORD] [–information] [–disk] [–no-smart] [–diskDevice PATH]
[–jobFile PATH] [–overwrite] [–writeSize SIZE] [–directory PATH] [–diskRuntime
DISKRUNTIME] [–cpu] [–cpuBurnTime TIME] [–network] [–iperfServer HOST] [–iperfTime TIME]
DESCRIPTION
Stressant is a simple yet complete stress-testing tool that forces a computer to perform a
series of test using well-known Linux software in order to detect possible design or
construction failures.
OPTIONS
-h, --help
show this help message and exit
--version
show program’s version number and exit
--logfile PATH
write reports to the given logfile (default: None)
--email EMAIL
send report by email to given address
--smtpserver HOST
SMTP server to use, use a colon to specify the port number if non-default (25).
willl attempt to use STARTTLS to secure the connexion and fail if unsupported
(default: deliver using the –mta command)
--smtpuser USERNAME
username for the SMTP server (default: no user)
--smtppass PASSWORD
password for the SMTP server (default: prompted, if –smtpuser is specified)
--information, --no-information
gather basic information (default: True)
--disk, --no-disk
run disk tests (default: True)
--no-smart, --smart
run SMART tests (default: False)
--diskDevice PATH
device to benchmark (default: /dev/sda)
--jobFile PATH
path to the fio job file to use (default:
/usr/share/doc/fio/examples/basic-verify.fio)
--overwrite
actually destroy the given device (default: False)
--writeSize SIZE
size to write to disk, bytes or percentage (default: 100M)
--directory PATH
directory to perform file tests in, created if missing (default: None)
--diskRuntime DISKRUNTIME
upper limit for disk benchmark (default: 1m)
--cpu, --no-cpu
run CPU tests (default: True)
--cpuBurnTime TIME
timeout for CPU burn-in (default: 1m)
--network, --no-network
run network tests (default: True)
--iperfServer HOST
iperf server to use (default: iperf.he.net)
--iperfTime TIME
timeout for iperf test, in seconds (default: 60)
EXAMPLES
Small run load with defaults:
stressant
Very fast test, useful to run if you are worried about crashing the machine:
stressant --writeSize 1M --cpuBurnTime 1s --iperfTime 1
Extensive test with complete disk wipe and SMART long test:
sudo stressant --writeSize 100% --overwrite --cpuBurnTime 24h --smart
# wait for the prescribed time, then show the SMART test results:
sudo smartctl -l selftest
Network test only on dedicated server:
stressant --no-information --no-cpu --no-disk --iperfServer iperf.example.net
Send test results by email:
stressant --email person@example.com
If the mail server refuses mail from your location, you can use another relay (password
will be prompted):
stressant --email person@example.com --smtpserver submission.example.net --smtpuser person --smtppassword
The stressant-meta package also depends on other tools that are not directly called by the
automated script above, but are documented below. The meta-package also suggests many more
useful tools.
Wiping disks
DANGER:
Wiping disks, just in case it’s not totally obvious, will DELETE DATA on the given file
or device. DO NOT run ANY command in this section unless you are sure you are writing
to the CORRECT DEVICE and that you REALLY want to DESTROY DATA.
As mentioned above, the stressant commandline tool can be used to directly wipe a disk
with the fio(1) command which is actually a disk-testing command that is abused for that
purpose. You may not have fio(1) installed on your machine, however, so you may also use
the venerable badblocks(8) command to test disks, without wiping them:
badblocks -nsv /dev/sdc
You can also wipe disks with the -w flag:
badblocks -wsv /dev/sdc
Be aware, however, that the effect of this will vary according to the physical medium. For
example, data may be recovered old spinning hard drives (HDD) if only the above technique
is used. For that purpose, you should use a tool like nwipe(1) that erases disks using
multiple passes and patterns:
nwipe --autonuke --nogui --method=random --verify=off --logfile=nwipe.log /dev/sdc
Those tools are also ineffective on solid state drives (SSD) as they have a more complex
logic layer and different layout semantics. For this, you need to use a “ATA secure erase”
procedure using the hdparm(8) command:
hdparm --user-master u --security-set-pass Eins /dev/sdc
time hdparm --user-master u --security-erase Eins /dev/sdc
More information about this procedure is available in the ATA wiki.
NOTE:
The “secure erase” procedure basically delegates the task of erasing the data to the
disk controler. Nothing garantees the destruction of that data, short of physical
destruction of the drive. See this discussion for more information.
Testing disks
A good way to test disks is to wipe them, as above, but that’s obviously destructive.
Sometimes you might want to just test the disk’s performance by hand, without wiping
anything. Stressant ships with fio(1) and bonnie++(1) for that purpose. The latter is
probably the simplest to use:
bonnie++ -s 4G -d /mnt/disk/ -n 1024
Make sure the file size (-s) is at least twice the main memory (see free -h). The
/mnt/disk directory should be writable by the current user as well.
Stressant itself, when disk tests are enabled, will run the following commands:
dd bs=1M count=512 conv=fdatasync if=/dev/zero of=/mnt/disk/testfile
dd bs=1M count=512 conv=fdatasync if=/mnt/disk/testfile of=/dev/null
hdparm -Tt /dev/disk
smartctl -t long /dev/disk
Those provide a quick overview of basic disk statistics as well.
More elaborate workloads can be done with fio. A simple benchmark could be:
fio --name=stressant --group_reporting --directory=/mnt/disk --size=100M
That is a basic read test. The result here, on a Western Digital Blue M.2 500GB Internal
SSD (WDS500G1B0B) with LUKS encryption, LVM and ext4, looks like:
Run status group 0 (all jobs):
READ: bw=267MiB/s (280MB/s), 267MiB/s-267MiB/s (280MB/s-280MB/s), io=100MiB (105MB), run=374-374msec
Disk stats (read/write):
dm-3: ios=323/0, merge=0/0, ticks=484/0, in_queue=484, util=70.99%, aggrios=511/0, aggrmerge=0/0, aggrticks=764/0, aggrin_queue=764, aggrutil=76.86%
dm-0: ios=511/0, merge=0/0, ticks=764/0, in_queue=764, util=76.86%, aggrios=511/0, aggrmerge=0/0, aggrticks=547/0, aggrin_queue=576, aggrutil=73.55%
sdb: ios=511/0, merge=0/0, ticks=547/0, in_queue=576, util=73.55%
A more realistic workload will ignore the cache (--direct=1), include random
(--readwrite=randrw) or sequential writes (--readwrite=readwrite), and parallelize the
test to put more pressure on the disk (--numjobs=4):
$ fio --name=stressant --group_reporting --directory=test --size=100M --readwrite=randrw --direct=1 --numjobs=4
Run status group 0 (all jobs):
READ: bw=45.8MiB/s (48.0MB/s), 45.8MiB/s-45.8MiB/s (48.0MB/s-48.0MB/s), io=199MiB (209MB), run=4346-4346msec
WRITE: bw=46.2MiB/s (48.5MB/s), 46.2MiB/s-46.2MiB/s (48.5MB/s-48.5MB/s), io=201MiB (211MB), run=4346-4346msec
Disk stats (read/write):
dm-3: ios=49674/50087, merge=0/0, ticks=10028/3912, in_queue=13972, util=97.22%, aggrios=50982/51423, aggrmerge=0/0, aggrticks=10204/3852, aggrin_queue=14092, aggrutil=96.62%
dm-0: ios=50982/51423, merge=0/0, ticks=10204/3852, in_queue=14092, util=96.62%, aggrios=50982/51423, aggrmerge=0/0, aggrticks=9042/2598, aggrin_queue=11224, aggrutil=92.54%
sdb: ios=50982/51423, merge=0/0, ticks=9042/2598, in_queue=11224, util=92.54%
There is, of course, way more information shown by the default fio output, including
latency distribution, but those are the numbers people first look for.
Parameters can be stored in a job file, passed as an argument to fio. Examples are
available in /usr/share/doc/fio/examples.
NOTE:
There are many other ways to test disks, obviously. In particular, simple tools like
disk-filltest might be considered for inclusion in the future, provided they enter
Debian.
Testing flash memory
Flash memory cards are known to sometimes be “fake”, that is, they misreport the actual
capacity of the card or the bandwith available. The stressant distribution therefore
recommends a tool called f3 which allows you to perform tests on the memory card. For
example, this is a probe on a honest memory card:
$ sudo f3probe --destructive --time-ops /dev/sdb
F3 probe 6.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
WARNING: Probing normally takes from a few seconds to 15 minutes, but
it can take longer. Please be patient.
Good news: The device `/dev/sdb' is the real thing
Device geometry:
*Usable* size: 30.00 GB (62916608 blocks)
Announced size: 30.00 GB (62916608 blocks)
Module: 32.00 GB (2^35 Bytes)
Approximate cache size: 0.00 Byte (0 blocks), need-reset=no
Physical block size: 512.00 Byte (2^9 Bytes)
Probe time: 4'57"
Operation: total time / count = avg time
Read: 3.07s / 4815 = 637us
Write: 4'51" / 4192321 = 69us
Reset: 324.5ms / 1 = 324.5ms
WARNING:
As the --destructive flag hints, this will destroy the data on the card, so backup the
data elsewhere before doing those tests.
Note that older versions of f3probe(1) (6.0 or earlier) will have trouble doing its job
unless the card is connected through a USB reader. Newer versions can deal with normal
block devices, provided that you pass the magic --reset-type=2 argument. Here’s such an
example, on a fake MicroSD card that is labeled and announced as 32GB but is actually
closer to 16GB:
root@curie:/home/anarcat/backup# ~anarcat/dist/f3/f3probe --destructive --time-ops --reset-type=2 /dev/mmcblk0
F3 probe 6.0
Copyright (C) 2010 Digirati Internet LTDA.
This is free software; see the source for copying conditions.
WARNING: Probing normally takes from a few seconds to 15 minutes, but
it can take longer. Please be patient.
Bad news: The device `/dev/mmcblk0' is a counterfeit of type limbo
You can "fix" this device using the following command:
f3fix --last-sec=30983327 /dev/mmcblk0
Device geometry:
*Usable* size: 14.77 GB (30983328 blocks)
Announced size: 31.25 GB (65536000 blocks)
Module: 32.00 GB (2^35 Bytes)
Approximate cache size: 7.00 MB (14336 blocks), need-reset=no
Physical block size: 512.00 Byte (2^9 Bytes)
Probe time: 2'29"
Operation: total time / count = avg time
Read: 1.57s / 32937 = 47us
Write: 2'27" / 200814 = 736us
Reset: 2us / 2 = 1us
To repair the device, you can repartition it quickly with the f3fix(1) command, as
recommended in the output:
f3fix --last-sec=30983327 /dev/mmcblk0
You will also need to reformat the partition so the new size is taken into account, for
example if this is a FAT32 filesystem:
mkfs.fat /dev/mmcblk0p1
You can also perform bandwidth tests with f3read(1) and f3write(1):
pmount /dev/sdb1
f3write /media/sdb1
f3read /media/sdb1
This allows you to detect hidden caches and fake sizes directly as well.
Network performance testing
The --iperfServer option of stressant runs a bandwidth test against a predefined (or
specified) server. You can, of course, call iPerf directly to run your own client/server
tests to find issues in specific routes on the network. The iperf3 package was chosen over
the older iperf because public servers are available for the test to work automatically.
iperf3 also has interesting performance features like --zerocopy and --file, see iperf3(1)
for details.
To run a test, start a server:
iperf3 --server
On another machine, connect to the server:
iperf3 --client 192.0.2.1
This runs a TCP test. You can specify UDP test on the client and disable bandwidth
limitations (otherwise UDP tests are limited to 1 Mbit/s):
iperf3 -c 192.0.2.1 --udp --bandwidth 0
To simulate a DDOS condition, you can try multiple clients and run the test for a longer
period:
iperf3 -c 192.0.2.1 -u -b 0 --parallel 50 --time 30
SEE ALSO
hdparm(8), smartctl(8), dd(1), fio(), stress-ng(1), iperf3(1)
AUTHOR
Antoine Beaupre
COPYRIGHT
2020, Antoine Beaupre
??? Feb 20, 2020 STRESSANT(1)