griobandwidth(1M)                                          griobandwidth(1M)



NAME
     grio_bandwidth - determines guaranteed-rate I/O device bandwidth

SYNOPSIS
     griobandwidth -d device -s iosize [ -ruwV ] [ -t sampletime ]
     griobandwidth -c controller -s iosize [ -ruwV ] [ -t sampletime ]
     griobandwidth -R -s iosize [ -fruwV ] [ -t sampletime ]

DESCRIPTION
     grio_bandwidth is used to determine the number of I/O operations of a
     given size that can be guaranteed to be performed by a given disk device,
     RAID subsystem or SCSI controller in one second.  It creates processes
     which repeatedly issue I/O requests of the given size, and device seeks
     of random lengths, to the specified devices.  The length of time to
     complete each request is recorded and this information is used to
     determine the average number of I/O operations that were performed by the
     device per second over the sample period.  This number is degraded by 10%
     to provide an approximation of the increase in I/O response time caused
     by a  heavily loaded system.  In addition, grio_bandwidth keeps track of
     the longest time to complete an I/O operation time over the sample period
     and calculates the number of such "worst case" operations that can be
     performed each second.  The system administrator can use grio_bandwidth
     to obtain the bandwidth information needed to create new entries in the
     Guaranteed Rate I/O device bandwidth information file /etc/grio_disks.

     The -d option is used to specify a single disk device. The disk name
     could be specified in the /dev/[r]dsk alias name format, or in the format
     reported back by -P, -C and -F options of the grio(1M) command.  The -c
     option is used to specify a single SCSI controller name. The name has to
     be specified in the format reported back by -P, -C and -F options of the
     grio(1M) command. This is also the same format used in
     /etc/ioconfig.conf.  The -R option will cause the utility to scan for all
     RAID devices attached to the system.  The -s option is used to specify
     the size of the I/O operation in bytes. It must be specified, there is no
     default value.  The -t option is used to specify the length of the sample
     period in seconds. By default the sample period has a length of 10
     minutes.  If the -u option is specified, the /etc/grio_disks file will be
     automatically updated with the device bandwidth information.  The -f
     option can only be used when both the -R and-u options are used. It
     indicates that when creating the entries in the /etc//grio_disk file, the
     RAID controller bandwidth should be split evening among all RAID luns
     attached to the controller. By default, the RAID controller bandwidth
     will be allocated to individual RAID luns on a first-come, first-served
     basis.  The user can use the -r and -w options to specify if device read
     and/or write operations should be performed.  By default only read
     operations will be performed on the device.  Normally, both -r and -w
     should be specifed so that the utility uses a mix of read and write
     operations when determining the bandwidth characteristics.  If it is
     known that on the device most Guaranteed Rate I/O rate guarantees will be
     used for performing either read or write operations, then the correct
     option may be specified to obtain a more accurate bandwidth
     characterization for the expected workload.  The -V option causes the



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griobandwidth(1M)                                          griobandwidth(1M)



     utility to produce more verbose output.  The utililty will use these
     values to determine the bandwidth performance characteristics of the
     device.  In the case of a single disk device, the performance
     characterisics of the device will be computed.  In the case of a RAID
     device, the performance characteristics of the RAID controllers, as well
     as the RAID luns, will be computed.

NOTES
     There are a number of factors to consider when using grio_bandwidth to
     determine the GRIO bandwidth characteristics of a RAID device.  First,
     the grio_bandwidth utility invokes the raidcli(5) utility to determine
     the RAID devices attached to the system.  In order to run the raidcli
     program successfully, the system must be a registered RAID agent.
     Second, it is important to re-run the utility each time the RAID device
     is reconfigured.  The RAID device is a complex mechanism and
     configuration changes will have performance impact.  Morover, in order to
     insure that the GRIO bandwidth rate guarantees can be met even when a
     RAID disk has failed, the bandwidth number must be computed when the
     device is in degraded mode.  When running in degraded mode (ie. one of
     the disk devices in each of the RAID luns is removed/missing), the RAID
     controllers on the RAID must compute the data for the missing disk.  This
     will increase I/O request response time.

FILES
     /etc/grio_disks

SEE ALSO
     ggd(1M), grio(1M), grio_disks(4), grio(5), raidcli(5), ioconfig(1M).



























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