Gmirror/graid or hardware raid?

[Paul Kraus]

On Jul 8, 2015, at 15:49, Mario Lobo <lobo at bsd.com.br> wrote:

> I'm building a server that is going to host VMs for a small e-commerce
> site. It's mainly going to be used for testing new solutions/improving the
> current site (on the cloud at this moment) but in the medium to long run,
> the idea is to hold the production site in it.

> Since I don't have any experience in running VMs for e-commerce, I don't
> know for sure if my plan is correct or even feasible.
> 
> I want to use FBSD 10 as the host OS and the VMs will run under Virtual Box.

I have been using FBSD / VBox to host both development and production sites for about 3 years now. None are E-commerce, but some are a pretty heavy load.

> It should be a Dell 430 server (or IBM equivalent) CPU Xeon E5-2630 with 4
> 2T SATA HDs/16 G Ram/ RAID PERC H730 controller (supported by mesas).

I am very, very rarely CPU limited. My biggest throttle is a combination of Internet connection and disk I/O.

> All VMs will run FBSD also with usual Apache/php/Mysql combination.
> 
> I really would welcome suggestions/opinions on what would be the most
> efficient way to set up those HDs to hold these virtual disks.
> 
> I thought about zfs but I won't have lots of RAM avaliable. Should I use
> the controller raid? Gmirror/Graid? What raid level?

That’s a tough one… A caching RAID controller can make a huge difference in disk performance, but you also run the risk of silent data corruption and I have never been really happy with the tools to monitor HW RAID controllers. With limited RAM the performance of ZFS can suffer. Does the PERC controller have an NVRAM cache and can it be setup one drive per presented volume ? I have down that and then used the presented volumes in a ZFS pool.

My latest VM server is an older Supermicro with 2 x X5550 CPU and 80 GB RAM (the last 16 GB to get to 96 was backordered when I needed to build it) and 4 x 500 GB WD RE series drives. Since I don’t need much space per VM, one pair of the drives is a ZFS mirror for the OS and the other pair is a ZFS mirror for the VMs. I would really rather stripe/mirror across multiple disks for the VM images, but the chassis only has 4 drive slots. This configuration is very fast for FBSD guests as well as Linux and Windows (Yes, I need them all).

But, my biggest concern with E-commerce would be the Internet connectivity and some type of fault tolerant load balancing. My highest profile production sites run on SmartOS instances out at Joyent. We are _hoping_ to have enough business in the next year to justify moving our own servers into a Tier-1 CoLo, but we can’t justify the cost (yet)...

--
Paul Kraus
paul at kraus-haus.org