s390-tools/tunedasd/man/tunedasd.8

.\" Copyright 2017 IBM Corp.
.\" s390-tools is free software; you can redistribute it and/or modify
.\" it under the terms of the MIT license. See LICENSE for details.
.\"
.TH TUNEDASD 8 "Apr 2006" "s390-tools"
.SH NAME
tunedasd \- A tool to adjust tunable parameters on DASD devices

.SH SYNOPSIS
.B tunedasd
[OPTION] COMMAND device

.SH DESCRIPTION
.B tunedasd
is a tool to adjust tunable parameters on DASD devices.
It can be used to modify the status of the device and to adjust
some performance relevant settings.
The DEVICE is the node of the device (e.g. '/dev/dasda') or a list of
devices separated by a space character.
Following functions are supported:
.IP "     -"
Get and reset the performance statistics profile per device.
.IP "     -"
Get and set the caching mode of the storage server.
This is only available for ECKD devices, because it is implemented using
ECKD Channel Program commands.
.IP "     -"
Reserve/Release/Unconditional Reserve a device.
This is only available for ECKD devices, because it is based on
the Control Unit functions.
.P
If
.B tunedasd
is called without parameter, it prints a short usage information and exits.
.SH OPTIONS
.TP
.BR "\-v" " or " "\-\-version"
Print version information, then exit.
.TP
.SH COMMANDS
.TP
.BR "\-h" " or " "\-\-help"
Print usage information, then exit.
.TP
.BR "\-g" " or " "\-\-get_cache"
Get current storage server caching behavior.
.TP
.BR "\-c" " or " "\-\-cache" " <behavior> "
Define caching behavior on storage server.
The following caching behaviors are currently supported by modern
Enterprise Storage Servers (ESS):
.br
.IP "          \(bu" 12
.I normal
('Normal Cache replacement'),
.IP "          \(bu" 12
.I bypass
(Bypass Cache),
.IP "          \(bu" 12
.I inhibit
(Inhibit Cache Loading),
.IP "          \(bu" 12
.I sequential
(Sequential Access),
.IP "          \(bu" 12
.I prestage
(Sequential Prestage),
.IP "          \(bu" 12
.I record
(Record Access)
.IP "" 7
More details about caching can be found in the 'Storage Control Reference' of the attached storage server.
.TP
.BR "\-n" " or " "\-\-no_cyl" " <n> "
Number of cylinders to be cached (only valid together with --cache).
.TP
.BR "\-S" " or " "\-\-reserve"
Reserve device.
.TP
.BR "\-L" " or " "\-\-release"
Release device.
.TP
.BR "\-O" " or " "\-\-slock"
Unconditional reserve device.
.br
.B Note:
Use with care, this breaks an existing reserve.
.TP
.BR "\-\-enable-stats"
Enable performance statistics globally.
.br
\fBNote:\fR Same as "echo 'set on' > /proc/dasd/statistics"
.TP
.BR "\-\-disable-stats"
Disable performance statistics globally.
.br
\fBNote:\fR Same as "echo 'set off' > /proc/dasd/statistics"
.TP
.BR "\-P" " or " "\-\-profile"
Print profile info of device.
.br
.B Note:
Profile info must be available and enabled in the kernel to get valid results
out of the profile commands. Enable statistics via \fB\-\-enable\-stats\fR.
.TP
.BR "\-Q" " or " "\-\-query_reserve"
Query the current reserve status of the device.
The following states are defined:
.br
.IP "          \(bu" 12
.I none:
The device is not reserved.
.IP "          \(bu" 12
.I implicit:
The device is not reserved, but there is a contingent or implicit
allegiance to this Linux instance.
.IP "          \(bu" 12
.I other:
The device is reserved to another operating system instance.
.IP "          \(bu" 12
.I reserved:
The device is reserved to this Linux instance.
.IP "" 7
More details about reserve/release can be found in the 'Storage Control Reference' of the attached storage server.

.TP
.BR "\-I" " or " "\-\-prof_item <row> "
Print single profile item data row (without header).
.br
Following rows are supported:
.br
.IP "          \(bu" 12
.I reqs
(# of dasd I/O requests),
.IP "          \(bu" 12
.I sects
(# of 512Byte sectors),
.IP "          \(bu" 12
.I sizes
(Histogram of sizes),
.IP "          \(bu" 12
.I total
(Histogram of I/O times),
.IP "          \(bu" 12
.I totsect
(Histogram of I/O times per sector),
.IP "          \(bu" 12
.I start
(Histogram of I/O time till ssch),
.IP "          \(bu" 12
.I irq
(istogram of I/O time between ssch and irq),
.IP "          \(bu" 12
.I irqsect
(istogram of I/O time between ssch and irq per sector),
.IP "          \(bu" 12
.I end
(Histogram of I/O time between irq and end),
.IP "          \(bu" 12
.I queue
(# of req in chanq at enqueuing)
.TP
.BR "\-R" " or " "\-\-reset_prof"
Reset profile info of device.
.TP
.BR "\-p" " or " "\-\-path_reset <chpid>"
Reset a channel path <chpid> of a selected device. A channel path
might be suspended due to high IFCC error rates or a High Performance
FICON failure. Use this option to resume considering the channel path
for I/O.
.TP
.BR "\-\-path_reset_all"
Reset all channel paths of the selected device. The channel paths
might be suspended due to high IFCC error rates or a High Performance
FICON failure. Use this option to resume considering all defined
channel paths for I/O.
.TP
.BR "\-s" " or " "\-\-copy\-pair\-swap <copy_pair>"
Swap the copy roles of the specified copy pair. The <copy_pair> has to
be a comma separated pair of \fBPRIMARY,SECONDARY\fR where
\fBPRIMARY\fR is the old primary device that will become a secondary
automatically. The old \fBSECONDARY\fR device will become the new
primary device. Both devices have to be online for this operation to
succeed.
.\"
.\".TP
.\".BR "\-o" " or " "\-\-online"
.\"Set the device online using the sysfs interface.

.SH EXAMPLE
1. Scenario: Get profile info for a device.
.br

       tunedasd \-P /dev/dasdc
       tunedasd \-PI irq /dev/dasdc

.br
2. Scenario: Set device caching mode to 1 cylinder 'prestage'.
.br

       tunedasd \-c prestage \-n 1 /dev/dasdc

.br
3. Scenario: Reset failed channel path with CHPID 45
.br

       tunedasd \-p 45 /dev/dasdc

.br
4. Scenario: Swap copy pair 0.0.9700 and 0.0.9740
.br

       tunedasd \-s 0.0.9700,0.0.9740 /dev/dasdc
.br
.SH "SEE ALSO"
.BR dasdview (8),
.BR dasdfmt (8),
.BR fdasd (8)