<font size=2 face="BookMaster-Bold"><b>Bob,</b></font><br><br><font size=2 face="BookMaster-Bold"><b> You can read ioql as
"IO queue length" (outside of GPFS) and "qsdl" as QOS
queue length at the QOS throttle within GPFS, computed from average delay
introduced by the QOS subsystem.</b></font><br><br><font size=2 face="BookMaster-Bold"><b>These "queue lengths"
are virtual or fictional -- They are computed by observing average service
times and</b></font><br><font size=2 face="BookMaster-Bold"><b>applying Little's Law. That
is there is no single actual queue but each IO request spends some time
in the OS + network + disk controller + .... </b></font><br><br><font size=2 face="BookMaster-Bold"><b>For IO bound workloads one can
verify that ioql+qsdl is the average number of application threads waiting
for IO.</b></font><br><br><font size=2 face="BookMaster-Bold"><b>Our documentation puts it this
way (See 4.2 Admin Guide, mmlsqos command)</b></font><br><br><br><font size=2 face="BookMaster-Bold"><b>iops= </b></font><font size=2 face="Palatino-Roman">The
performance of the class in I/O operations per second.</font><br><br><font size=2 face="BookMaster-Bold"><b>ioql= </b></font><font size=2 face="Palatino-Roman">The
average number of I/O requests in the class that are pending for reasons
other than being</font><br><font size=2 face="Palatino-Roman">queued by QoS. This number includes,
for example, I/O requests that are waiting for network or</font><br><font size=2 face="Palatino-Roman">storage device servicing.</font><br><br><font size=2 face="BookMaster-Bold"><b>qsdl= </b></font><font size=2 face="Palatino-Roman">The
average number of I/O requests in the class that are queued by QoS. When
the QoS system</font><br><font size=2 face="Palatino-Roman">receives an I/O request from the
file system, QoS first finds the class to which the I/O request</font><br><font size=2 face="Palatino-Roman">belongs. It then finds whether the
class has any I/O operations available for consumption. If not,</font><br><font size=2 face="Palatino-Roman">then QoS queues the request until
more I/O operations become available for the class. The </font><font size=2 face="BookMaster">Qsdl</font><br><font size=2 face="Palatino-Roman">value is the average number of I/O
requests that are held in this queue.</font><br><br><font size=2 face="BookMaster-Bold"><b>et= </b></font><font size=2 face="Palatino-Roman">The
interval in seconds during which the measurement was made.</font><br><br><font size=2 face="Palatino-Roman">You can calculate the average service
time for an I/O operation as </font><font size=2 face="Palatino-Italic"><i>(Ioql
+ Qsdl)/Iops</i></font><font size=2 face="Palatino-Roman">. For a system
that is</font><br><font size=2 face="Palatino-Roman">running IO-intensive applications,
you can interpret the value </font><font size=2 face="Palatino-Italic"><i>(Ioql
+ Qsdl) </i></font><font size=2 face="Palatino-Roman">as the number of
threads in</font><br><font size=2 face="Palatino-Roman">the I/O-intensive applications.
This interpretation assumes that each thread spends most of its time in</font><br><font size=2 face="Palatino-Roman">waiting for an I/O operation to
complete.</font><font size=2 face="sans-serif"><br></font><br><br><br><br><br><font size=1 color=#5f5f5f face="sans-serif">From:
</font><font size=1 face="sans-serif">"Oesterlin, Robert"
<Robert.Oesterlin@nuance.com></font><br><font size=1 color=#5f5f5f face="sans-serif">To:
</font><font size=1 face="sans-serif">gpfsug main discussion
list <gpfsug-discuss@spectrumscale.org></font><br><font size=1 color=#5f5f5f face="sans-serif">Date:
</font><font size=1 face="sans-serif">03/08/2016 10:53 AM</font><br><font size=1 color=#5f5f5f face="sans-serif">Subject:
</font><font size=1 face="sans-serif">[gpfsug-discuss]
Interpreting "mmlsqos" output</font><br><font size=1 color=#5f5f5f face="sans-serif">Sent by:
</font><font size=1 face="sans-serif">gpfsug-discuss-bounces@spectrumscale.org</font><br><hr noshade><br><br><br><font size=1 face="Helvetica">So \u2013 I enabled QoS on my file systems
using the defaults in 4.2 Running a restripe with a class of \u201cmaintenance\u201d
gives me this for mmlsqos output:</font><br><br><font size=1 face="Helvetica">[</font><font size=1 face="Courier">root@gpfs-vmd01a
~]# mmlsqos VMdata01 --sum-nodes yes</font><br><font size=1 face="Courier">QOS config:: enabled</font><br><font size=1 face="Courier">QOS values:: pool=system,other=inf,maintenance=inf</font><br><font size=1 face="Courier">QOS status:: throttling active, monitoring
active</font><br><font size=1 face="Courier">=== for pool system</font><br><font size=1 face="Courier">10:36:30 other iops=9754 ioql=12.17 qsdl=0.00022791
et=5</font><br><font size=1 face="Courier">10:36:30 maint iops=55 ioql=0.067331 qsdl=2.7e-05
et=5</font><br><font size=1 face="Courier">10:36:35 other iops=7999.8 ioql=12.613
qsdl=0.00013951 et=5</font><br><font size=1 face="Courier">10:36:35 maint iops=52 ioql=0.10034 qsdl=2.48e-05
et=5</font><br><font size=1 face="Courier">10:36:40 other iops=8890.8 ioql=12.117
qsdl=0.00016095 et=5</font><br><font size=1 face="Courier">10:36:40 maint iops=71.2 ioql=0.13904 qsdl=3.56e-05
et=5</font><br><font size=1 face="Courier">10:36:45 other iops=8303.8 ioql=11.17 qsdl=0.00011438
et=5</font><br><font size=1 face="Courier">10:36:45 maint iops=52.8 ioql=0.08261 qsdl=3.06e-05
et=5</font><br><br><font size=3 face="Helvetica">It looks like the \u201cmaintenance\u201d class
is getting perhaps 5% of the overall IOP rate? What do \u201cioql\u201d and \u201cqsdl\u201d
indicate? </font><br><br><font size=1 face="Helvetica">Bob Oesterlin<br>Sr Storage Engineer, Nuance HPC Grid<br>507-269-0413</font><br><tt><font size=2>_______________________________________________<br>gpfsug-discuss mailing list<br>gpfsug-discuss at spectrumscale.org<br></font></tt><a href="http://gpfsug.org/mailman/listinfo/gpfsug-discuss"><tt><font size=2>http://gpfsug.org/mailman/listinfo/gpfsug-discuss</font></tt></a><tt><font size=2><br></font></tt><br><BR>