This kind of took my by surprise. I am running ESXi 5.5 on the following:
i7 - 3770
2TB Hitachi 3.5" drive
1TB Seagate 3.5" drive
500GB Seagate 3.5" drive
ESXi 5.5 runs pretty well considering my lack of spindles. I only run into issues when I have a handful or more VMs running from the same drive. I thought more spindles should make things run better overall and I looked into a two drive Synology or other NAS type of device but I figured local storage would perform much better than being connected through the network (even at gigabit).
I got a good deal on 8 2.5" Seagate Thin 500GB 7200 SATA III drives and purchased an ICY Dock 8 bay SATA enclosure. I had an IBM ServeRAID MR10i card hanging around and connected the 8 drives to it. I was hoping to use a RAID 10 config, but the card only had RAID 0, 1, 5 and 6 available so I chose RAID 5 and ESXi saw the datastore immediately. I used all 3.XTB available for the datastore and proceeded to create a Server 2012 R2 VM using an .ISO file from the Hitachi loaded into the "CD drive" on the new VM, and created the VM on the new 8 drive datastore. Much to my dismay, it performed TERRIBLY! It was much faster using the same configuration with individual drives, no RAID! I thought more spindles would make a HUGE difference in performance, but unfortunately, it's terrible. I'm sure there is some type of configuration that maybe I'm missing. The RAID card is SATA II but in reality, most don't realize true 6Gbps unless they are using SSD drives.
The RAID card does have a battery backup, but the battery appears to be dead so I am using write through (not write cache). I know this will have an effect on performance, but good grief! I can't imagine it being that severe.
On a single drive when I load a new OS, it quickly runs through the menu items "copying files", "setting up windows", etc but this time it took what seemed like forever. I can normally setup a server, login for the first time, install VM Tools, change the IP and name and reboot by the time this was half way through copying the files (second step).
Does anyone have an idea? I specifically got 7200RPM 6GB drives thinking that this will be the best scenario compared to SAS, but man is it awful. I didn't expect them to be as fast as SAS drives, but I absolutely expected better performance than that of a single drive. Any ideas would be greatly appreciated.
I'm still looking into the card to figure out if there is a firmware update, but for those keeping score at home, the RAID card is an IBM ServeRAID MR10i running firmware v1.40.262.1180.
Thanks in advance!
One more thing, this is just a machine I play with in my home lab. There are no "production" devices or VMs on it. I use it to learn VMware and test different server scenarios, etc.