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Appendix D Quality of Service Guide
Configuration
StorNext 3.5 Installation Guide 146
available. SNFS relies on the correct setting in the configuration file; if the
storage system changes (for example, because of a new disk array,) the
user must re-qualify the I/O subsystem to determine the amount of
bandwidth available. This amount will be specified in the FSM
configuration file. The user can also specify the minimum amount of
bandwidth to be provided to non-real-time applications.
There are five keywords controlling QOS that can be specified in the
stripe group section of the FSM configuration file. Not all keywords need
be present. Typically, the user specifies the RTIO bandwidth in terms of
either number of I/O operations per second (
rtios) or megabytes per
second (
rtmb). Keywords are not case sensitive.
For a minimum configuration, only the real-time limit (either rtios or rtmb)
need be specified. All other configuration variables default to reasonable
values.
Table 28 QOS Configuration
Keywords
Name Description Default
Rtios
The maximum number of real-
time I/Os allowed in a stripe
group during any one-second
period.
0 (no real-time)
Rtmb
Maximum amount of real-time
MB/sec allowed on the stripe
group during any one-second
period.
0 (no real-time)
RtiosReserve
Amount of reserve in I/Os/sec
from the maximum allowed for
non-real-time I/Os. Must be
greater than the equivalent to
1MB/sec or the amount that can
be transferred to a single stripe
line.
Equivalent to
1MB/sec
RtmbReserve
Amount to reserve in MB/sec
from the maximum allowed for
non-real-time I/O.
Must be
greater than 1.
1MB/sec
RtTokenTimeout
Time in seconds to wait for clients
to respond to a token callback.
2 seconds