stressant

STRESSANT(1) Stressant STRESSANT(1)

NAME

   stressant - Stressant Documentation

SYNOPSIS

   stressant  [-h] [–version] [–log [PATH]] [–email EMAIL] [–smtpserver HOST] [–smtpuser USERNAME] [–smtppass PASSWORD] [–no-information] [–no-disk] [–smart] [–diskDevice PATH] [–jobFile
   PATH] [–overwrite] [–writeSize SIZE] [–directory PATH] [–diskRuntime DISKRUNTIME] [–no-cpu] [–cpuBurnTime TIME] [–no-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  con‐
   struction 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: stressant-$HOSTNAME.log)

      --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: de‐
             liver 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)

      --no-information, --information
             gather basic information (default: True)

      --no-disk, --disk
             run disk tests (default: True)

      --smart, --no-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)

      --no-cpu, --cpu
             run CPU tests (default: True)

      --cpuBurnTime TIME
             timeout for CPU burn-in (default: 1m)

      --no-network, --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 pur‐
   pose. 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.

Benchmarking 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.

   Stressant itself actually runs the equivalent of this:

      fio --name=stressant --group_reporting --runtime=1m <(sed /^filename=/d /usr/share/doc/fio/examples/basic-verify.fio ; echo size=100m) --filename=test

   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 disks

   The above actually tests disks in the sense that it looks at its performance, but it’s more a benchmark than a “test”. For tests, stressant will do a smartctl run if the --smart argu‐
   ment is provided. What it actually does is:

      smartctl -t long /dev/sdX

   Then smartctl -l selftest /dev/sdX can be used to track progress.

   But this doesn’t work for all drives. For example, it may fail for external USB enclosures.

   smartmontools’s NVMe support is particularly limited. nvme-cli might be able to deal with those drives better. In theory, it should support running tests with:

      nvme device-self-test /dev/nvme0

   But in practice, that often fails because the devices sometimes do not support self-test at all. You can look at the smart-log instead:

      nvme smart-log /dev/nvme0

   If the num_err_log_entries entry is non-zero, you can look at the actual log:

      nvme error-log /dev/nvme0

   NOTE:
      The above doesn’t detail how to interpret the output of those commands, and probably should. Sorry.

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