# Please help to choose the hardware for host for virtualization



## makos (Aug 31, 2011)

Hi everyone!

Iâ€™ve used search but there is not much info to help with estimating Host machine resources.  
So it would be great if someone will help me to choose correct hardware to build a Virtualization project.

OK. Here are the requirements:
GUEST SERVER ( DC / Application and database server / File Sharing server)
Windows 2003 or 2008 Server with following services:
 - AD
 - File Sharing, DFS
 - ERP application server (recommended server hardware requirements by developers: 2 x Intel Xeon CPU 2.4Ghz / 2Gb RAM / 2 x SCSI U320 HDD Storage)
 - MSSQL server 2003 or 2008 with 4Gb ERP database (up to 20% size increase yearly)
 - Backup solution (something like Symantec)
 - HDD space ~500 Gb
40 x Windows XP SP3 guests with following services:
 - MS Office 2010
 - ERP application client (recommended client hardware requirements: PIII 866Mhz / 256 Mb RAM)

I would like to have a FreeBSD as a host OS with ZFS RAID as storage backend.
For Windows Server guest 2xCores 2-4Ghz / 4GB RAM I think will be enough, and for Windows XP guests - 1xCore 2-4Ghz / 512Mb RAM.

How to calculate correctly how many physical resources will be needed?
   1)	RAM: 4GB for guest server + 40x 512MB for Win XP guests =  24Gb + 8 GB for Host OS. 
        Do I really need to match physical RAM amount with virtual? 
   2)	CPU: What CPU would be better Core i7 or Xeon. 
        How many physical CPUs?
   3)	Storage backend â€“ a common bottleneck. 
        Please suggest a good ZFS topology to achieve a good performance.
        For ex: 6x 1Tb 7200rpm SATA HDD stripped and mirrored Vdevs (RAID10 ) as a backend for guests + SSD for ZIL and L2ARC + 3x 1Tb SATA HDDs in RAIDZ for backup.
        Or I will need a separate storage solution like NAS or something?

Thanks for help!
Max.


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## AndyUKG (Aug 31, 2011)

Hi,

  it's really impossible to tell you what to buy. If you already had these systems running on non-virtualised servers and could provide some info on load patterns etc then someone could have a stab at saying what might be appropriate for a virtualised server. Without any info on load its impossible.

If you can't do any real world load testing before buying your kit then the best thing you can do is have a stab at something that seems about right, and try and work out how you can upgrade it if its not sufficient. Ie a server that can have additional CPU's or a design that allows you to use multiple servers.

To answer one of your questions, physical RAM will indeed be the sum of all your client RAM needs plus more for the host OS (if you are running ZFS this will be a lot more for ARC). Physical CPUs goes back to depending on the actual client loads you will have.

Regarding ZFS, again totally depends on the client loads. You can start really slow, say a 3 5200rpm SATA disks in RAIDz, and go up to really fast, say tens of SAS disks in RAID1. You can also use dedicated ZIL and ARC2 disks as you mentioned.

What are you planning to use, VirtualBox?

Andy.


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