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diff --git a/upstream/opensuse-leap-15-6/man1/tapestat.1 b/upstream/opensuse-leap-15-6/man1/tapestat.1 new file mode 100644 index 00000000..23e93966 --- /dev/null +++ b/upstream/opensuse-leap-15-6/man1/tapestat.1 @@ -0,0 +1,263 @@ +.TH TAPESTAT 1 "JULY 2018" Linux "Linux User's Manual" -*- nroff -*- +.SH NAME +tapestat \- Report tape statistics. +.SH SYNOPSIS +.B tapestat [ -k | -m ] [ -t ] [ -V ] [ -y ] [ -z ] [ --human ] [ +.I interval +.B [ +.I count +.B ] ] +.SH DESCRIPTION +The +.B tapestat +command is used for monitoring the activity of tape drives connected to a system. + +The first report generated by the +.B tapestat +command provides statistics +concerning the time since the system was booted, unless the +.B -y +option is used, when this first report is omitted. +Each subsequent report +covers the time since the previous report. + +The +.I interval +parameter specifies the amount of time in seconds between +each report. +The +.I count +parameter can be specified in conjunction with the +.I interval +parameter. If the +.I count +parameter is specified, the value of +.I count +determines the number of reports generated at +.I interval +seconds apart. If the +.I interval +parameter is specified without the +.I count +parameter, the +.B tapestat +command generates reports continuously. + +.SH REPORT +The +.B tapestat +report provides statistics for each tape drive connected to the system. +The following data are displayed: + +.B r/s +.RS +The number of reads issued expressed as the number per second averaged over the interval. + +.RE +.B w/s +.RS +The number of writes issued expressed as the number per second averaged over the interval. + +.RE +.B kB_read/s | MB_read/s +.RS +The amount of data read expressed in kilobytes (by default or if option -k used) or +megabytes (if option -m used) per second averaged over the interval. + +.RE +.B kB_wrtn/s | MB_wrtn/s +.RS +The amount of data written expressed in kilobytes (by default or if option -k used) or +megabytes (if option -m used) per second averaged over the interval. + +.RE +.B %Rd +.RS +Read percentage wait - The percentage of time over the interval spent waiting for read requests +to complete. +The time is measured from when the request is dispatched to the SCSI mid-layer until it signals +that it completed. + +.RE +.B %Wr +.RS +Write percentage wait - The percentage of time over the interval spent waiting for write requests +to complete. The time is measured from when the request is dispatched to the SCSI mid-layer until +it signals that it completed. + +.RE +.B %Oa +.RS +Overall percentage wait - The percentage of time over the interval spent waiting for any +I/O request to complete (read, write, and other). + +.RE +.B Rs/s +.RS +The number of I/Os, expressed as the number per second averaged over the interval, where +a non-zero residual value was encountered. + +.RE +.B Ot/s +.RS +The number of I/Os, expressed as the number per second averaged over the interval, that +were included as "other". Other I/O includes ioctl calls made to the tape driver and +implicit operations performed by the tape driver such as rewind on close +(for tape devices that implement rewind on close). It does not include any I/O performed +using methods outside of the tape driver (e.g. via sg ioctls). +.RE +.RE +.SH OPTIONS +.IP --human +Print sizes in human readable format (e.g. 1.0k, 1.2M, etc.) +The units displayed with this option supersede any other default units (e.g. +kilobytes, sectors...) associated with the metrics. +.IP -k +Show the amount of data written or read in kilobytes per second instead of megabytes. +This option is mutually exclusive with -m. +.IP -m +Show the amount of data written or read in megabytes per second instead of kilobytes. +This option is mutually exclusive with -k. +.IP -t +Display time stamps. The time stamp format may depend +on the value of the S_TIME_FORMAT environment variable (see below). +.IP -V +Print version and exit. +.IP -y +Omit the initial statistic showing values since boot. +.IP -z +Tell +.B tapestat +to omit output for any tapes for which there was no activity +during the sample period. + +.SH CONSIDERATIONS +It is possible for a percentage value (read, write, or other) to be greater than 100 percent +(the +.B tapestat +command will never show a percentage value more than 999). +If rewinding a tape takes 40 seconds where the interval time is 5 seconds the %Oa value +would show as 0 in the intervals before the rewind completed and then show as approximately +800 percent when the rewind completes. + +Similar values will be observed for %Rd and %Wr if a tape drive stops reading or writing +and then restarts (that is it stopped streaming). In such a case you may see the r/s or w/s drop to zero and the %Rd/%Wr value could be higher than 100 when reading or writing continues +(depending on how long it takes to restart writing or reading). +This is only an issue if it happens a lot as it may cause tape wear and will impact +on the backup times. + +For fast tape drives you may see low percentage wait times. +This does not indicate an issue with the tape drive. For a slower tape drive (e.g. an older +generation DDS drive) the speed of the tape (and tape drive) is much slower than filesystem I/O, +percent wait times are likely to be higher. For faster tape drives (e.g. LTO) the percentage +wait times are likely to be lower as program writing to or reading from tape is going +to be doing a lot more filesystem I/O because of the higher throughput. + +Although tape statistics are implemented in the kernel using atomic variables they cannot be +read atomically as a group. All of the statistics values are read from different files under +/sys, because of this there may be I/O completions while reading the different files for the +one tape drive. This may result in a set of statistics for a device that contain some values +before an I/O completed and some after. + +This command uses rounding down as the rounding method when calculating per second statistics. +If, for example, you are using dd to copy one tape to another and running +.B tapestat +with an interval of 5 seconds and over the interval there were 3210 writes and 3209 reads +then w/s would show 642 and r/s 641 (641.8 rounded down to 641). In such a case if it was +a tar archive being copied (with a 10k block size) you would also see a difference between +the kB_read/s and kB_wrtn/s of 2 (one I/O 10k in size divided by the interval period of 5 +seconds). If instead there were 3210 writes and 3211 reads both w/s and r/s would both show +642 but you would still see a difference between the kB_read/s and kB_wrtn/s values of 2 kB/s. + +This command is provided with an interval in seconds. However internally the interval is +tracked per device and can potentially have an effect on the per second statistics reported. +The time each set of statistics is captured is kept with those statistics. The difference +between the current and previous time is converted to milliseconds for use in calculations. +We can look at how this can impact the statistics reported if we use an example of a tar +archive being copied between two tape drives using dd. If both devices reported 28900 kilobytes +transferred and the reading tape drive had an interval of 5001 milliseconds and the writing +tape drive 5000 milliseconds that would calculate out as 5778 kB_read/s and 5780 kB_wrtn/s. + +The impact of some retrieving statistics during an I/O completion, rounding down, and small differences in the interval period on the statistics calculated should be minimal but may be non-zero. +.SH ENVIRONMENT +The +.B tapestat +command takes into account the following environment variables: + +.IP S_COLORS +When this variable is set, display statistics in color on the terminal. +Possible values for this variable are +.IR never , +.IR always +or +.IR auto +(the latter is the default). + +Please note that the color (being red, yellow, or some other color) used to display a value +is not indicative of any kind of issue simply because of the color. It only indicates different +ranges of values. + +.IP S_COLORS_SGR +Specify the colors and other attributes used to display statistics on the terminal. +Its value is a colon-separated list of capabilities that defaults to +.BR H=31;1:I=32;22:M=35;1:N=34;1:Z=34;22 . +Supported capabilities are: + +.RS +.TP +.B H= +SGR (Select Graphic Rendition) substring for percentage values greater than or equal to 75%. + +.TP +.B I= +SGR substring for tape names. + +.TP +.B M= +SGR substring for percentage values in the range from 50% to 75%. + +.TP +.B N= +SGR substring for non-zero statistics values. + +.TP +.B Z= +SGR substring for zero values. +.RE + +.IP S_TIME_FORMAT +If this variable exists and its value is +.BR ISO +then the current locale will be ignored when printing the date in the report +header. The +.B tapestat +command will use the ISO 8601 format (YYYY-MM-DD) instead. +The timestamp displayed with option -t will also be compliant with ISO 8601 +format. + +.SH BUGS +.I /sys +filesystem must be mounted for +.B tapestat +to work. It will not work on kernels that do not have sysfs support + +This command requires kernel version 4.2 or later +(or tape statistics support backported for an earlier kernel version). + +.SH FILES +.I /sys/class/scsi_tape/st<num>/stats/* +Statistics files for tape devices. + +.I /proc/uptime +contains system uptime. +.SH AUTHOR +Initial revision by Shane M. SEYMOUR (shane.seymour <at> hpe.com) +.br +Modified for sysstat by Sebastien Godard (sysstat <at> orange.fr) +.SH SEE ALSO +.BR iostat (1), +.BR mpstat (1) + +.I https://github.com/sysstat/sysstat + +.I http://pagesperso-orange.fr/sebastien.godard/ |