|Hi there |
I'm using ESXi 4.1 with just one 1TB SATA drive to play with some installations at home.
Since some time ago I noticed significant decrease in performance of my VM's. At first I thought it's a network issue but today I discovered the following:
1. Copying a file from one VM to another VM on the same drive:
100% 68MB 216.9KB/s 05:20
2. Copying the same file from a VM to my Laptop via network: 100% 68MB 33.9MB/s 00:02
As you see sending the same file via the network takes significantly less time than from VM to VM on the same drive.
Any ideas on what's going on ?
Much will depend on the capability of the disk controller. If this isn't a hardware RAID controller with write caching enabled you will definitely suffer performance issues. While it may seem that reading and writing to the same device should be fast you are sharing that device with two operating systems or more and ESXi. ESXi must constantly be changing access to disk IO from one VM to the other. One OS is reading and the other is writing. With no caching capability each read or write must totally complete before control is given from one VM to the other. This is compounded with many running VMs which will also share IO access even if they aren't doing much. You may have other issues and it is worth checking logs to see if there are other error conditions.
I'm sure my motherboard has RAID capabilities I'm just not sure about the cashing part.
i will need to buy 3 hard drives in order to set Raid5.
And then I will need to transfer all VM's over to the new datastore.
Anything else I should be aware of while performing all those tasks ?
RAID means more spindle, but without a good controller cache with RAID5 you will have still performance problem during write operation.
So check your RAID card and otherwise (if you need also good performance in write I/O) choose RAID1+0
6* SATA2 300MB/s ports -
Intel Matrix Storage utility supports software RAID 0, 1, 10 & 5(Windows)
LSI MegaRAID driver supports software RAID 0, 1& 10(Windows & Linux)
So is this RAID any good ?
General concensus is that software RAID sucks donkey parts when it comes to use with ESX/ESXi... Not to mention you won't see the RAID array as a single volume, but as individual drives... ESX/ESXi [currently] only recognizes RAID arrays built with hardware RAID controllers.
As per the link it shows as software RAID. It is possible that the motherboard has a dedicated slot for adding a Cache module. I would check the documentation and the ASUS website.
So I bought 3 x 500GB harddrives, arranged them in RAID 0 (I understand the risk) using the Software RAID configuration utility in the BIOS of my motherboard.
During the installation process of ESXi 4.1 i can see three drives instead of one (strange), so I pick the first one when ESXi asks on which drive do you wan't to install the ESXi. Installation goes fast and smoothly but after the reboot I get this:
"Boot error" .
What would be the reason of that please ?
ESX(i) does NOT support software RAID. You would need to get a hardware RAID controller. If not you will be limited to individual drives as you see now.
If ESXi gets installed to a single drive you may need to change the boot order in the BIOS. Just choose one of the other drives in the BIOS until you find the correct one. You might want to change the SATA cabling so the one with the ESXi install is first.
I had a quick look and it doesn't appear that the motherboard supports what is generally called a zero slot RAID controller. Those have a dedicated slot that would allow the addition of a RAID processor and RAM cache to the existing onboard interface.