BZ1882568: Added OS Disk requirements for installation

Requirements added

Adding OSDisk requirements

Adding OSDisk requirements

Implemented review comments

Author: snarayan-redhat

modules/installation-azure-limits.adoc

@@ -61,6 +61,13 @@ You can [provide an install-config](../overview.md#multiple-invocations) to
 [configure](customization.md) the installation program to use specific zones to override the defaults.
 ////
 
+|OS Disk
+|7
+|
+|VM OS disk must be able to sustain a minimum throughput of 5000 IOPS / 200MBps. This throughput can be provided by having a minimum of 1 TiB Premium SSD (P30). In Azure, disk performance is directly dependent on SSD disk sizes, so to achieve the throughput supported by `Standard_D8s_v3`, or other similar machine types available, and the target of 5000 IOPS, at least a P30 disk is required.
+
+Host caching must be set to `ReadOnly` for low read latency and high read IOPS and throughput. The reads performed from the cache, which is present either in the VM memory or in the local SSD disk, are much faster than the reads from the data disk, which is in the blob storage.
+
 |VNet
 | 1
 | 1000 per region