How to select next free datastore from cluster

[#1]

This code for a scriptable task will first get all the available datastores of a given cluster, then select only those where the name is matching a given pattern and then select the first one with enough space.

INPUTS:

vmCluster (VC:ClusterComputeResource) //Your Cluster

storageSum (number) //A previously calculated value for the needed storage

OUTPUTS:

vmDatastore (VC:Datastore) //A datastore with enough free space

CODE:

allStorage = vmCluster.datastore;
var vmStorage = new Array();
var storageName;
for (ii in allStorage)
{
    storageName = allStorage[ii].name
    if (storageName.substring(6,9) ==  "CLS")
    {
        vmStorage.push(allStorage[ii]);
    }
}
var ii = 0;
var vmStorageInfo;
var vmStorageLength = vmStorage.length;
while(vmDatastore == null && ii < vmStorageLength)
{
    //extract storageinfo and compare free space to needed space
    vmStorageInfo = vmStorage[ii].info;
    if ((vmStorageInfo.freeSpace / 1073741824) >= storageSum) //1073741824 = 1024*1024*1024 = 1GB
    {
        vmDatastore = vmStorage[ii];
    }
    ii++;
}

If you have any questions or suggestions, feel free to comment.

Regards

Andreas

[Andreas_Diemer]

Hi Andreas,

• Why do you use for each and then iterate by increment ii+
  
• Why do you use an additional array counter
  

var allStorage = new Array();
var allStorage = vmCluster.datastore; //this line initialize the array also
var vmStorage = new Array();
var ii = 0;
var kk = 0;
var storageName;
for each (VcDatastore in allStorage)

for (ii in allStorage)
{
    //extract the name of the storage and compare part of it to a string
    storageName = allStorage[ii].name
    if (storageName.substring(6,9) ==  "CLS")
    {
        vmStorage.push(allStorage[ii]);
        kk++;
    }
    ii++;
}


Less code, more readable

Regards, Andreas

[Aramaki]

Hi Andreas,

i wrote it in about 15 minutes and it worked for me. Didn't have the time to optimize.

Oh and i didn't know, how to iterate without the ii when using a for each.

And i did forget about the push-method.

Thanks for the corrections

[Andreas_Diemer]

Hi Andreas,

no problem - I don't want to teach you - just to give some hints, because it is a community document and so it should / could be a blueprint for other user / starters.

Regards, Andreas

[dstamen]

i am trying to implement this but i feel like im missing a few steps...i create a scriptable task and enter this info...is the storagesum a parameter or attribute?

[pabloramos]

Aramaki, I would like to use this workflow, but I am very new to vOrch and JavaScript. I understand that you are using the substring call to specifically look for "CLS." That is too specific for my environment today. Do you have a sample line that I can use to do a pattern matching (regex) way to find the appropriate DS. For example I would like to match on something like this: "vm_"_"*"_ where we pass variables ba=business area, perftier=performance tier, and continuitytier=continuity tier.

[jacksonecac]

To add to this it might be helpful for some users to take a piece off the top of the datastore. By that I mean, sometimes datastores cannot be filled to capacity to account for certain apps or backup processes. Therefore something like

(((vmStorageInfo.freeSpace - (vmStorageInfo.freeSpace * 0.10)) / 1073741824) >= storageSum))
would make sure that you always maintain 10% of the datastore to reserve for other running processes.