+++ /dev/null
-WARNING: Running sgp_dd will ERASE the contents of the disk devices.
- This is NOT to be run on any OST where you care about any data
- or you are not expecting to reformat the filesystem afterward.
-
-Requirements
-------------
-
-. sg3_utils (for sgp_dd)
- SCSI device
- Or, if using non-scsi disk
- raw device support
- sg3_utils
-
-
-Overview
---------
-
-This survey may be used to characterise the performance of a SCSI device.
-It simulates an OST serving multiple stripe files. The data gathered by it
-can help set expectations for the performance of a lustre OST exporting the
-device.
-
-The script uses sgp_dd to do raw sequential disk I/O. It runs with
-variable numbers of sgp_dd threads to show how performance varies with
-different request queue depths.
-
-The script spawns variable numbers of sgp_dd instances, each reading or
-writing a separate area of the disk to show how performance varies with the
-number of concurrent stripe files.
-
-The device(s) used must meet one of two tests:
-SCSI device:
- Must appear in the output of 'sg_map'
-Raw device:
- Must appear in the output of 'raw -qa'
-You may not mix raw and SCSI devices in the test specification.
-
-
-Running
--------
-
-The script must be customised according to the particular device under test
-and where it should keep its working files. Customisation variables are
-described clearly at the start of the script.
-
-When the script runs, it creates a number of working files and a pair of
-result files. All files start with the prefix given by ${rslt}.
-
-${rslt}_<date/time>.summary same as stdout
-${rslt}_<date/time>_* tmp files
-${rslt}_<date/time>.detail collected tmp files for post-mortem
-
-The summary file and stdout contain lines like...
-
-total_size 8388608K rsz 1024 thr 1 crg 1 180.45 MB/s 1 x 180.50 = 180.50 MB/s
-
-The number immediately before the first MB/s is the bandwidth computed by
-measuring total data and elapsed time. The other numbers are a check on
-the bandwidths reported by the individual sgp_dd instances.
-
-If there are so many threads that sgp_dd is unlikely to be able to allocate
-I/O buffers, "ENOMEM" is printed.
-
-If not all the sgp_dd instances successfully reported a bandwidth number
-"failed" is printed.
-
-
-Visualising Results
--------------------
-
-I've found it most useful to import the summary data (it's fixed width)
-into Excel (or any graphing package) and graph bandwidth v. # threads for
-varying numbers of concurrent regions. This shows how the device performs
-with varying queue depth. If the series (varying numbers of concurrent
-regions) all seem to land on top of each other, it shows the device is
-phased by seeks at the given record size.
-
-
-The included script, parse.pl will process output files and create .csv files fo spreadsheet import
-
git://git.whamcloud.com / fs / lustre-release.git / blobdiff