The best approach may just consider to build an independent Active/Passive or Active/Active SQL cluster to support the infrastructure. A backup for the SQL is always recommended to create recovery point in the event of data corruption. Most data on the SQL databases is the configuration changes, log and etc. Similar to VMWare vCenter Database.

Related posts:

1. XenDesktop License Server Flexibility

what if the license server go down, will all the existing connections or sessions been terminated automatically?

He had explained as the configuration in the license server and license files are design to prevent the point of failure in the scenario of license server unavailable due to any failures. You will be given 28 days period of time with unlimited seats in the event of license servers unavailable during the outage.

In normal scenario, assume your license server is functioning with 1000 seats, you will also allow to provision 10% extra within 28 days before you increase the purchased licenses. This will allow you to turn on extra capacity temporally in the short period.

Related posts:

1. New license offer from VMware vSphere 5 on 3rd party VDI solution

Citrix Systems commissioned Tolly to evaluate the performance of Citrix XenApp when running on Citrix XenServer 5 and compare that with XenApp running on VMware ESX 3.5u3.

Testing focused on system scalability and user quality-of-experience. This test report was approved for publication by VMware. The VMware End User License Agreement (EULA) requires such approval.

The testing was conducted in accordance with Tolly Common RFP #1101, Virtual Server Performance. That document is available for license and you can find more information about it on the Tolly Common RFP website.

Download the free Citrix/VMware report as below:

Register and Download!

If you’re looking at technical point of view, personally I think VMware competitor is few year behind VMware vSphere. Check out more detail about VMware vSphere 4 Cheat Sheet posted by Jason Boche.

Referring to costing, I don’t agreed with what Citrix presented during the event this morning. You’re always try to tell customer pay if you need it. What are you talking about? Are you trying to tell Enterprise customers don’t use HA or don’t use those features provided? How about Microsoft Hyper-V cost comparison?

Again, I would said I’m not sure how true chart show as above and the most important is apple to apple comparison.

In fact, there are many many kind of comparison between VMware, Microsoft Hyper-V and Citrix Xen. Please feel free to contact us, we’re willing to share with you!

I did a quick test and I would like to share my personal review about Citrix XenServer 5.0:

Personally I think network speed is fast compare to VMware ESX. I have a physical 1Gbps NIC network speed and I can get 2Gbps network speed after install XenTools on Windows 2008 server but require 2 times reboot(SuSE Linux require 1 reboot). Anyway VM guest shutdown and reboot process is faster than VMware ESX.

I was try to install SuSE Linux 10 using 4 ISO CD (both NFS or CIFS), the Citrix XenServer always give me an error “The VM rejected the attempt to detach the device xxxxx refusing to close” when switch ISO CD1 to ISO CD2. You have to extract 4 ISO CD into one single location to make it work or copy ISO to local storage(provider you have enough local disk space).

The enterprise product should not have similar issue and this is not make sense at all.

Anyway, you can try alternative way using “Install URL” instead of using ISO Image once you have extract ISO CD into single folder on your web server.

Install URL: http://xx.xx.xx.xx/inst/10/32/SP2/ALL
Advanced Boot OS Parameters:
console=ttyS0 xencons=ttyS hostip=xx.xx.xx.xx/24 gateway=xx.xx.xx.xx dnsserver=xx.xx.xx.xx

Please make sure your have correct IP, gateway and DNS setup properly else you will getting error during installation.

Add and remove any disk/storage on Window 2008 or SuSE Linux 10 no downtime or reboot required. The VM guest OS will detect automatically.

Convert to template and VM clone features which are another features behind VMware ESX.

Once you have converted to template, you won’t have another way to reverse back as VM guest machine. It’s one way operation which you will received a warning before convert to template as show below.

Right click VM guest, and click Copy VM will do VM cloning but require downtime. The Copy VM feature is disable during VM guest is power on.

Overall, I would said VMware ESX still my first choice.

But if we compare the technology today, I believe most of us will see that from virtual cpu perspective, VMware had been quite slow respond on that. If you do spoke to most of the VMware representative or consultant, they always told you not to allocate more than 1 Vcpu if not required.

In real world, I believe that non of us will be satisfied with the single core performance for our server environment. Dual core is been in the market for more than 2 years, and quad core had been also popularize to most of us. Single core will just be SLOW in most of the event. I am here to urge VMware to push harder for more virtual CPU per VM. The thing that should consider is to compare with the competitor products like Xen and Xensource.

In Xen, you will allow to configure 8 vcpu per VM if your host have 8 cores. That meant you should able to configure 16 cores per VM if your host do have 4 x quad cores today. I am yet to test with 16 cores per VM as my machine is come with 2 x quad cores.

I even try to run a VM with Windows 2008 which contains 8GB memory and 8 virtual cpu assign. The VM is run on local storage on the SATA disk. The performance on the VM is just fast compare to 4 vcpu VM I had in ESX. Again, not to say VMware is not good, and I strongly believe VMware is still the best today, but they are little behind with the delay of more vcpu per VM.

Basically the new version come with 2.6.18 kernel version of Linux as the host system.

The Xen 3.3.0 features including:

• Power management (P & C states) in the hypervisor
• HVM emulation domains (qemu-on-minios) for better scalability, performance and security
• PVGrub: boot PV kernels using real GRUB inside the PV domain
• Better PV performance: domain lock removed from pagetable-update paths
• Shadow3: optimisations to make this the best shadow pagetable algorithm yet, making HVM performance better than ever
• Hardware Assisted Paging enhancements: 2MB page support for better TLB locality
• CPUID feature levelling: allows safe domain migration across systems with different CPU models
• PVSCSI drivers for SCSI access direct into PV guests
• HVM framebuffer optimisations: scan for framebuffer updates more efficiently
• Device passthrough enhancements
• Full x86 real-mode emulation for HVM guests on Intel VT: supports a much wider range of legacy guest OSes
• New qemu merge with upstream development
• Many other changes in both x86 and IA64 ports

Download Xen 3.3 datasheet

Download Xen 3.3.0 official source distribution tarball

Download Linux 2.6.18 with Xen 3.3.0 support source tarball