Hello Friends.
I am an SQA Engineer and need to do a lot of testing on the applications in windows and want better performance.
I have gone through a lot of articles but could not find the correct answer for my questions.
I need help from the experts like you to better understand the concepts and the configuration which I need.
To give a short details of what I do and my requirements.
Details of the test machine which I have for performing my task. ESX 5.1 with U1
VM Configuration: ESX 5.1 with U1
Even after having a good configuration in hardware it takes a lot of time to perform the above activities.
Q1. I need to know will "RAID 0" help me in this scenario and what stripe size should I use for best random R/W.
Q2. Need to know if I do a write of a 4k file in guest since VMFS block size is of 1M does it actually write 1M on the physical disk.
Does this actually translate to 1M divided by 8 disk all writing their 128k strip block.
Ad.Q1: Of course it will, but if you want really good disk-i/o, consider SSD. I'm running just a few VMs, but since I switched to SSD, everything is amazingly fast (i.e. W7 boot-time just a few seconds)...
Hello Jarry,
I understand that SSD will improve the performance but as it is company hardware I will have to do with it.
About the RAID part, I am already using RAID 0 but still not getting that performance so wanted a technical reason why.
If RAID 0 is not going to give that performance will RAID 5 or RAID 10 help in this case.
Hi,
Could you please explain when you say about performance. I understand currently you are on Raid 0. When you say performace what excatly you mean.
You haven't mentioned whether your RAID card has a cache or not. ESXi doesn't provide any software level caching like the Windows OS does, and performance on ESXi is generally accepted as being garbage on the cheaper cards which don't provide this facillity in hardware. It's certainly the most common cause of "my storage is slow" type complaints here.
It would also appear you have hard disks of the slower variety. Not being able to afford SSD is one thing - but using 15K drives is a huge benefit and at 1TB I don't expect your disks are of this style. Finally, you state that every VM is configured with 4 vCPU. With a reasonable number of virtual machines, this would lead to a high level of contention and odds are you could increase performance by lowering vCPU count, rather than just declaring every VM needs this much "for performance".
The only people RAID0 helps is people doing nothing but reading the results of benchmark software. There is no excuse to use it.
Hello noelfrancis2
When I say Performance I mean to say that the work I am doing which is listed above on that machine should be done at much faster rate.
Like Installing windows should not take 30 Min. If I take the same server and instead of ESX, I install windows directly on the host it takes 5 min.
So where am I loosing the performance if I install the same OS inside the VM.
-Thanks
Hello,
To me it looks like some issues with the configuration. Could you please share the specification of the HDD which you are using. Have you tried with any other Raid apart from Raid 0. I would also recommand you please have the VM tools reinstalled. If possible i would recommand a complete power cycle and then try to reinstall the VM tools.
Good Luck and keep us posted.
1) How many of these VMs are running? If you have more than 3, you should not expect it to perform as well as physical, as you are overcommitting the host. Given you have 5, I wouldn't expect equal-to-native performance.
2) Your RAID 0 a a good choice for performance, but you do realize it carries a VERY VERY high risk of data loss, right?
3) The 4k write in a guest gets passed to the hardware as a 4k write....the 1MB allocation size is irrelevant in the case of guest OS IO.
XSERV wrote:
If RAID 0 is not going to give that performance will RAID 5 or RAID 10 help in this case.
RAID 5 or 10 will not give you better performance, only increased redundancy from the very low in a 8 disk RAID 0 set.
How you looked at any Performance counters inside the vSphere Client? Checked out the CPU load and memory usage? And likely most important in this case, the disk usage (reads/writes per second, latency and more.)