[gpfsug-discuss] RAID type for system pool

[Frederick Stock]

My guess is that the "metadata" IO is for either for directory data since 
directories are considered metadata, or fileset metadata.

Fred
__________________________________________________
Fred Stock | IBM Pittsburgh Lab | 720-430-8821
stockf at us.ibm.com



From:   "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   09/10/2018 02:27 PM
Subject:        [gpfsug-discuss] RAID type for system pool
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Hi All, 

So while I’m waiting for the purchase of new hardware to go thru, I’m 
trying to gather more data about the current workload.  One of the things 
I’m trying to do is get a handle on the ratio of reads versus writes for 
my metadata.

I’m using “mmdiag —iohist” … in this case “dm-12” is one of my 
metadataOnly disks and I’m running this on the primary NSD server for that 
NSD.  I’m seeing output like:

11:22:13.931117  W       inode    4:299844163        1    0.448  srv dm-12 
                <redacted>
11:22:13.932344  R    metadata    4:36659676         4    0.307  srv dm-12 
                <redacted>
11:22:13.932005  W     logData    4:49676176         1    0.726  srv dm-12 
                <redacted> 

And I’m confused as to the difference between “inode” and “metadata” (I at 
least _think_ I understand “logData”)?!?  The man page for mmdiag doesn’t 
help and I’ve not found anything useful yet in my Googling.

This is on a filesystem that currently uses 512 byte inodes, if that 
matters.  Thanks…

Kevin

—
Kevin Buterbaugh - Senior System Administrator
Vanderbilt University - Advanced Computing Center for Research and 
Education
Kevin.Buterbaugh at vanderbilt.edu - (615)875-9633


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