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Himanshu_vmware
Enthusiast
Enthusiast

How to determine how many vmdks can I keep in one datastore, considering that OS vmdk goes in to raid5 datastores and data vmdks in raid10 datastores

esxi and vcenter version 5.1

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a_p_
Leadership
Leadership

vSphere 5.1 supports up to 30,720 files per VMFS3 volume (see https://www.vmware.com/pdf/vsphere5/r51/vsphere-51-configuration-maximums.pdf). For a VMFS5 volume the maximum ist 130,690.

André

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Himanshu_vmware
Enthusiast
Enthusiast

Okay, But what about the performance, is that going to give me performance if I am going to keep multiple vmdks in it.

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a_p_
Leadership
Leadership

Not necessarily. There are many factors to take into account to determine how to configure an environment for best performance, like number of disks, disk types (SAS/SATA/SSD), disk speed, the data on the virtual disks and its change/access rate ....

André

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Jimmy15
Enthusiast
Enthusiast

What kind of datastore (disk size/type) you are on.

Regards

Pankaj


regards



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asharma25
Contributor
Contributor

Hi Himanshu,

As per my opinion, You have to do some math before placing your OS and DATA VMDK on different Datastores.

1 . You have to check how many IOPS you are receiving from the LUN of RAID 5 and RAID 10.

2. Then you have to check the IOPS requirement of each of the VMDK.

To identify the available IOPS of RAID 5 or RAID 10 LUNs. You have to check the disk type of the RAID group and the number of disk involve in the RAID group. Every disk has it's own IOPS capacity. You can refer the below diagram to identify the disk wise IOPS.

pastedImage_0.png

You can fetch the total available IOPS through below formula.

Total RAW IOPS = Disk IOPS * Number of Disks

Lets assume, you have 10 disks of 15 K in your RAID 5. So in this scenario you will get total IOPS = 1750

Total IOPS = 175 * 10

I assume, all the disks are 1 TB of space. So you will get approx. 8.38 TB of usable space with 1750 IOPS. Now lets move to datastore level. Suppose you have provisioned 2TB of space to one your LUN and provisioned it in your ESXi as your one DATASTORE. Now in this case you will get approx 417 IOPS over this datastore.

After doing all above math, now you have to move on each VMDK level. Lets place all the VMDK on different datastores and run ESXTOP in batch mode.

You will get some log as a result of ESXTOP after couple of hours. Please analyse it into windows perfmon and fetch the details of IOPS of each disk. You will get the data look like attached image.

Now you have all the details and can place the VMDK according to the statistical data and ensure to get the better performance.

Jimmy15
Enthusiast
Enthusiast

by using Storage profile this can be achieve. make one profile for OS disks (RAID5) and another for data disks (RAID10).

During provisioning or later on, like in our environment we are placing OS disks in Bronze and Data disks on Silver/Gold.

Gold are SSD disks while Bronze and Silver disk are less performing.

regards

Pankaj


regards



PS: Mark kudos or correct answer as appropriate 🙂