Appendix D Quality of Service Guide

Configuration

Name

Description

Default

 

 

 

RtiosReserve

Amount of reserve in I/Os/sec

Equivalent to

 

from the maximum allowed for

1MB/sec

 

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.

 

 

 

 

RtmbReserve

Amount to reserve in MB/sec

Must be

 

from the maximum allowed for

greater than 1.

 

non-real-time I/O.

1MB/sec

 

 

 

RtTokenTimeout

Time in seconds to wait for clients

2 seconds

 

to respond to a token callback.

 

 

 

 

RTIO Upper Bound

The limit will be specified in terms of I/Os per second (parameter Rtios) or in terms of MB/sec (parameter Rtmb). Case is not sensitive. Note that I/Os per second are I/Os of any size to the disk subsystem. Either or both may be specified. If both are specified, the lower limit is used to throttle

I/O. If neither is specified, no real-time I/O is available on the stripe group. These parameters are applied to a stripe group definition.

[StripeGroup MyStripeGroup]

Rtios 2048

Rtmb 10

The above example specifies that the storage system can support a maximum of 2048 I/Os per second at any instant, aggregate among all the clients, or 10 MB/sec, whichever is lower.

Most real-time I/O requests will be a stripe line at a time to maximize performance. Non-real-time I/Os will be a minimum of a file system block size.

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