EMC VNX Performance Analysis – 1
Posted by Brajesh Panda on September 5, 2012
- You must have Navisphere/Unisphere Analyzer Enabler installed on the storage array
- Analyzer Enabler (license) will help to generate readable statistics log files, called as NAR files.
- Without this license it will generate encrypted logs (NAZ files) and you may need help of EMC support analyze the same.
- Make sure you start “Statistics Logging” from system properties
- Then you have to set Logging Interval & Log file Archive Interval parameters
In VNX you will find these options in
- “System -> Monitoring and Alerts -> Statistics for Block -> Performance Data Logging”
Configure below parameters;
- Real time Interval – Required for real time performance overview monitoring
- Archive Interval – After this much of seconds it is going to pull out data and write into the NAR file.
- Periodic Archiving – Make sure this option is checked. This option helps to create periodic new NAR files.
- As per EMC Community Documentation, each NAR or NAZ file will contain 155 polling intervals of data called data points. Therefore if we set the Archive Interval to 120secs, it will create new NAR file in each 5hrs 10mins (155 x 120sec = 18600sec/60sec=310min/60min=5hr10min). If we set the interval to 300secs, it will create new NAR file in each 12hr55min
- Once each NAR file is full it creates another file. Having said that if we have bigger SAN environment it make take more time to pull the data from SP. So default 120 value may not work here, we may like to increase to 300sec. But higher intervals may miss key details about heavily loaded drives in a Pool. So In case of VNX while doing performance troubleshooting it is recommended to set Archive Interval to 60secs & no more than 300sec.
- Real Time interval is recommended to set lower or equal to archive interval because you will be watching real time graphs in Unisphere.
- Before we change the archival time it is recommended to stop the logging, hence it will dump all data to NAR file and close that. And while you start with new time period it will start with new interval values.
- NAR/NAZ file title contains the date & time (in GMT) of last data point logged.
- Next step for analysis is to download those Archive Log files. Well for a given day you may get 2 or more Archive files as per your archival interval setting. So we would like to merge those files into a single file so it will be easy to analyze them.
- To retrieve, to merging & for analysis we can use Unisphere Archive Management feature directly from the storage box or naviseccli command line tool. But we need to be connected to the SAN over wire.
- But if you want to do offline analysis, we need to install Unisphere Client & Unisphere Server Software (downloadable from EMC Powerlink) & use the same to open the NAR files for analysis.
- Regarding merging; either thru Unisphere or naviseccli we can only merge two files. But when we have multiple file, like A.NAR, B.NAR, C.NAR; 1st we have to merge A & B and then we have to merge the C file with the merged output of A & B. This step can be scripted
Having said that merging there some key points regarding to merge;
- We should not merge NAR files from storage processor A & B. They are the same files
- We should not merge large number of files for number of days. Because Analyzer display in Unisphere can only display 156 data points. So depending on the time frame you specify (say Monday through Thursday worth of data) it will begin merging data points to satisfy this 156 point requirement. Then a two minute average turns into an average of say 1.5 hours and the data is basically useless. But they can be exported to CSV & can be worked with Spreadsheet.
Let’s download Unisphere Server Software from https://powerlink.emc.com, you need a user account & password. It is free though
- I installed both softwares in my workstation
- Started Unisphere client from Program & trying to log in to my local Unisphere server(127.0.0.1); got below error.
- Because I didn’t have ssl cert in my workstation. Hence I need at least self-sign certificate to get it work.
- If you want to read about how to generate a self-sign certificate, read my other article over here
- After you install a SSL cert in your workstation, try to login again. It will throw certificate not trusted error. You can click “Accept Always” & move forward.
- Upon clicking Accept Always, it will ask you to confirm to initialize Unisphere Global Security; click yes
- Then it will ask you to create a user with password. I preferred same default sysadmin Unisphere comes with.
- Click Okay & click Yes in next window to create the user for the local Unisphere
- Now you can login to the local Unisphere
In next article we are going work with those NAR files using this local Unisphere Server software.