VSA Multisite

[dajma00]

We are planning to build a multisite VSA solution.  Few questions if people can guide us:

1. What is the difference between buying hardware with VSA software from HP and just buying software from HP and running it on our own Dell or IBM servers?  Is there any advantage in going with HP hardware?

2. If we just buy VSA software from HP and run it on our own servers, what sort of servers will be required?

3. Should the VSA servers be separated from other ESXi VMs?  I mean do we need to dedicate VSA machines and have our production VMs on separate servers or we can run both our production VMs and VSA on the same hosts?

4. Very briefly what would be the comparison of HP VSA with for example EMC VPlex?  It seems that HP VSA is offering everything that VPlex offers at a much lower price.  Is that correct?  Will we be missing out on something if went with HP VSA instead of EMC VPlex?

Regards,

Amjad.

[oikjn]

there is no way to answer your questions as you give no no actual numbers for requirements. 

In general, you can use the VSA software or get the HP hardware package.  It all depends on your environment and what you would rather do.  The hardware is a single source item so you can work out any problems with HP if something comes up.  Along with that, there are a limited number of versions, but the performance of those units is well enough established.

You can get the same or even more performance out of a VSa using the software version, but it all depends on the hardware the VSA is running on.  If you roll some crazy pure SSD VSA system I"m sure it will smoke the performance of the hardware VSAs, but when you have a problem with the hardware side of the equation you will have to work that one out on your own.

I use software VSAs and have used them on dedicated machines and shared production machines.  I can't say I found significant difference between the two for performance, but I guess it depends on how hard you stress the systems.  Just make sure that youg et something with as fast a single core speed as you can afford as CPU can become a bottleneck issue for the software VSAs.

The great thing about the software VSA is that if you already have the hardware you were thinking of adding the VSAs to, you can download the software now and run a trial that is fully functional for 60 days.  Just run and benchmark and figure out if it meets your needs.  With enough playing around with the trialware you can get a great understanding of the software package that runs both the software and the hardware systems and you can see where you are weak/stong on for perfomance.

I don't really know much about the other opeion you mentioned, but keel in mind that with network raid as used by HP, you effectively loose 1/2 of your storage capacity AFTER whatever hardware raid level you use (HP uses hardware raid5).  If you use hardware raid10 and network raid10 you effictively need 4x the raw storage capacity in order to meet your provisioned storage requirements... people often overlook this fact until they actually get the units in house and then they are upset about not having the storage capacity they thought they would have.

[dajma00]

Thanks for this guidance.

We are planning to purchase HP or Dell Intel E7 based machines with maximum clock speeds available.

We downloaded the VSA and are testing it right now.

[oikjn]

perfect.  the trial VSAs are completely full function so you know what you are getting for performance and features on the software side and at least know the features on the hardware side.

I find the CMC software is a bit weak for historical reporting for performance stats, but it is good for live stats.  Make sure to play with the CMC software a lot!  Right click on everything to make sure you find all the bells and whistles.  I"m sure you will end up messing up some stuff, but its the best way to learn.  The default performance stats the CMC show are a bit weak and I changed my defaults to show a lot more usefull information to me.  It will be critical for you to watch those stats to figure out if the software VSAs are enough for you or if you need hardware VSAs and if so, how many nodes are required.

[Prakash Singh_1]

For information on Multi site SAN you browse here, http://h20584.www2.hp.com/hpgt/guides/select?lang=en&cc=in&prodTypeId=12169&prodSeriesId=3936136&lang=en&cc=in and select options Designing and implementing Multi-Site HA/DR Solution.

[Gediminas Vilutis]

By using VSA you add additional hypervisor layer with some impact to performance. Our tests showed that SAN/IQ on VSA performs about 20-30% slower than on bare metal. Also bare P4500 node combines bandwith of 2 1GE NICs, in VSA you can add only one NIC (lower bandwith for iniciators). But if your loads are not high, this is not an issue. 

There is no much difference where you run VSAs - on dedicated or shared ESXi nodes, as long as you have enough resources (RAM, CPU, network, disk IO). We have one customer with 3 ESXi nodes cluster, where he runs everything - VMs and VSAs. No complains for 2 years.

BTW, VSA on MS Hyper-V performs better than on VMware - keep in mind if you decide to go with dedicated VSA nodes ;)

Gedas