vSphere Design: Storage IOPS
A friend of mine asked me this question: "Any idea roughly how much IOPS should we estimate for a VM? My estimate is about 400 IOPS per VM – taking physical server for comparison. SAS disk is about 200 IOPS and typically, a server would have 2xHDD for OS, so total IOPS is about 400 IOPS. However, this number can be quite big especially if we have many VMs. I’m now struggling with provisioning more capacity than needed for VMware environment to meet the IOPS requirement. This actually drive up the storage cost." My reply as was follows after a short thinking: Correction. Typically server with RAID 1 does not have 2 x IOPS. It has 1 x IOPS. Its not writing to two HDDs but its mirror to one by the raid controller. Two things to note. Yes take the physical server IOPS using the worse scenario; 1. for database server, 2. for a normal app server. Size two types of datastores, 1. with higher IOPS cater for database; 2. for normal app server. If you can use SSD ...