iostat-wrapper

Wrap iostat outputs into array of object.

Introduction

Wrapper around iostat for Node, providing 3 methods. Methods providing EventEmitter/Promise to get information, and an extra method only for data conversion.

Methods

RunIOStat(args): Run iostat and provide an EventEmitter to handle the output from iostat.

Data comes back as an event 'data'. You can bind the event like

    iostat.RunIOStat().on('data', (data, error)=>{
        console.log(data);
    });

Process(args): Provide an Promise to wrap RunIOStat method. This is to facilitate the use of .then() and await.

    iostat.Process(['-x']).then(data => {
        console.log(data);
    })

ToObject(rawOutput): Convert raw string output of iostat into array of objects. Returns an array.

Data schema

As the returned value, data would be an Array of Objects of this kind of form :

    [{ 
        Cpu: 
        { 
            '%user': 1.11,
            '%nice': 0.01,
            '%system': 1.11,
            '%iowait': 0.1,
            '%steal': 0,
            '%idle': 97.67 
        },
        Device: 
        { 
            'sda': 
            { 
                'rrqm/s': 1.23,
                'wrqm/s': 1.23,
                'r/s': 1.23,
                'w/s': 1.23,
                'rMB/s': 1.23,
                'wMB/s': 1.23,
                'rsec/s': 123.4,
                'wsec/s': 123.4,
                'avgrq-sz': 12.3,
                'avgqu-sz': 0.12,
                'await': 12.34,
                '%util': 12.34
            } 
        } 
    }]

The schema of data would be different according to the output of iostat. Only parameters in the returned table title of iostat cmdlet is included.

error will give out the error message if there is anything wrong with running iostat.

If need to run iostat in continuous mode, like with arguments ['-x','-m','1','2'], you will recieve an array of 2 objects. For now, this package can only return converted value after the iostat process is over. That is to say, when you run iostat with args like ['-x', '1'], the wrapper cannot give you any return value but keep waiting.

Takes iostat arguments as an array, ['-x', '-m'] by default. e.g : iostat.RunIOStat(['-x','-m', '1','2']) is to actually run iostat -x -m 1 2, and register an event emitter to return the output value after converted it into array of objects.

Examples

    var iostat = require('iostat-wrapper');
    iostat.RunIOStat(['-x','-m','1','2']).on('data', function(data, error) {
        console.log(stats);
        if (stats[0].Device.sda && stats[0].Device.sda["%util"] > 1)
            console("Too Heavy");
    });

    var iostat = require('iostat-wrapper');
    var data = await iostat.Process(['-x','-m','1','2']);
    console.log(100 - data[1].Cpu['%idle']);