[gpfsug-discuss] Fileheat reporting

[Marc A Kaplan]

FILE_HEAT value is a non-negative floating point value.  The value can 
grow quite large -- in theory it can grow to the IEEE 64 bit maximum 
floating point value and maybe even to "infinity". 

Each time a file is read completely from disk it's FILE_HEAT value 
increases by 1.  If a fraction, f,  of the file is read then FILE_HEAT += 
f.  (f<=1)
On the other hand, as time passes the FILE_HEAT "decays" at the rate given 
by the (mmchconfig) parameters fileHeatPeriodMinutes and 
fileHeatLossPercent.

In fact I recently corresponding with a customer (who is no stranger to 
this forum and may wish to comment!) who found that a bunch of hot little 
script files had accumulated heat values greater than 100,000,000 !  We 
were both surprised.   Apparently these files are read and re-read many 
times every day by many nodes and so their heat builds up! 

So what would you call "Hot", "Warm", "Cold"?  It depends...  To get a 
good idea, I suggest that a "survey" of FILE_HEAT values be done by using 
an mmapplypolicy command with a rule like.

rule 'y' list 'fhn0' weight(FILE_HEAT)
 SHOW(HEX(XATTR('gpfs.FileHeat')) ||
   ' A=' || varchar(ACCESS_TIME) ||
   ' K=' || varchar(KB_ALLOCATED) ||
   ' H=' || varchar(FILE_HEAT))

 where FILE_HEAT != 0.0

Using `mmapplypolicy FS -P policy-rules-file -I defer -f /tmp/whatever 
[other options such as...   -N nodeclass  -g /shared-temp ...  ]

This will produce a file list sorted by FILE_HEAT, which you can then 
peruse or otherwise process....
Perhaps a histogram or other display of   (number of files) vs (heat 
values) would be interesting...




From:   Andreas Landhäußer <alandhae at gmx.de>
To:     gpfsug-discuss at spectrumscale.org
Date:   10/04/2016 08:54 AM
Subject:        [gpfsug-discuss] Fileheat reporting
Sent by:        gpfsug-discuss-bounces at spectrumscale.org




Customer needs a report of filenames being Hot, warm and cold.

As far as I'm understanding fileheat can be any value larger than zero.
A value of zero or almost zero equals to COLD

How am I classifying warm and hot?

I'm needing a standardized value between 0 and 1 for fileheat. Is it 
possible creating such a number when when activating fileheat and creating 

reports and finally using ILM policies according to this classification?

Best regards

Andreas



-- 
Andreas Landhäußer  +49 151 12133027 (mobile)
alandhae at gmx.de_______________________________________________
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