joebrug Trusted Contributor.
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VM - iSCSI or FC?

Looking into purchasing a SAN, pretty early stages at the moment, but am hearing different things regarding running VM's. Are any of you running ESX server with an iSCSI SAN? how is it working? any noticable difference between running VM's over a iSCSI san vs a FC one?

Also, is anyone familiar with Pillar Data Systems? specifically the Axiom 300? I like the idea of the unit.. specifically removing the need to have to deal with setting up raid groups, etc, you just basically create LUNs and give them a priority. not sure if things like EMC/EqualLogic work the same way

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Anonymous_User Absent Member.
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Re: VM - iSCSI or FC?

joebrug wrote:

> Looking into purchasing a SAN, pretty early stages at the moment, but am
> hearing different things regarding running VM's. Are any of you running
> ESX server with an iSCSI SAN?


*raises hand*

> how is it working?


Pretty darn good.

> any noticable
> difference between running VM's over a iSCSI san vs a FC one?


Not sure as don't have a fiber channel SAN to compare this to. We
bought a cheap server from nixsys.com and loaded it down with SATA
drives (12 500GB drives), I installed SLES10 on it, then I installed the
iSCSI target software. The three ESX hosts are using QLogic iSCSI HBAs.
This is a temporary solution that we're probably only going to use a
couple more months. Then we're going to look into purchasing a
commercial SAN, probably from EMC or NetApp or EqualLogic or LeftHand.
I still don't know if I'm going to stick with iSCSI or move to FC, but
if I can get away with it I want to stick with iSCSI. I just want to
make sure I've got enough I/O for everything we do. While GW isn't
virtualized yet, I hope to get it there later this year.

At any rate, eventually we are going to implement a second SAN in our DR
site (next year) and due SAN-to-SAN replication. The SAN we buy for
this office in a couple of months will be the first piece. Of course
this is going beyond what you were asking.

So in the end, the answer to whether you should run iSCSI or FC is "it
depends." It depends on how many ESX hosts will be hitting the box, how
many VMs per box, how disk I/O intensive those VMs are, will you be
exposing raw LUNs to the VMs or just using flat VMDK files, etc. My
personal hunch is that in all but the most disk intensive cases that
iSCSI will be just fine.

--
Joe
"Those of you who think you know everything are annoying to those of us
who do."
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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

joebrug <joebrug@no-mx.forums.novell.com> expounded:

> Looking into purchasing a SAN, pretty early stages at the moment, but am
> hearing different things regarding running VM's. Are any of you running
> ESX server with an iSCSI SAN? how is it working? any noticable
> difference between running VM's over a iSCSI san vs a FC one?


We have a fibre channel SAN in ours and have taken a big look at iSCSI.
The EqualLOgic people had a lot to say about it. Talks with our telecom
folk were equally productive.

A lot of it comes down to what kind of I/O ops are you hauling over your
transmission channel? FC can get to 4Gb these days, which beats out 1Gb
ethernet... though 10Gb ethernet is 'just around the corner'. The
concentration of I/O ops generally speaking is your disk unit, so that's
the item that'll see the most contention.

At a network layer, a well designed network shouldn't be a problem. In our
case the iSCSI host and the servers hitting it will all be on the same
Cisco 6509 switch so we should have no problems hauling at line-speeds.
When we put something in our DR site, we have 10Gb ether over to that and
we've only cracked 20% on that ONCE which was during a test. No problems
there.

FC does have a home in highly transactional systems, and those are the
kinds of systems I do not consider strong virtualization candidates
anyway. For things like web-servers or medium usage database servers I
can't see a real difference between FC and iSCSI right now.

iSCSI does need a well designed ethernet. If you don't have that, FC is
better.

Just some thoughts from me 🙂

--
--Borg Consulate--
Tape backup, the bane of my existance
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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

For the record Equallogic rocks. It's incredibly impressive. We had 9
of their arrays at my last job and they were bulletproof, incredibly
flexible, and easy.

Joseph Marton wrote:
> Then we're going to look into purchasing a
> commercial SAN, probably from EMC or NetApp or EqualLogic or LeftHand. I
> still don't know if I'm going to stick with iSCSI or move to FC, but if
> I can get away with it I want to stick with iSCSI.

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

Travis wrote:
> For the record Equallogic rocks. It's incredibly impressive. We had 9
> of their arrays at my last job and they were bulletproof, incredibly
> flexible, and easy.


That's good to know. I have been looking at their stuff and it does
look pretty nice.

Brad
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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

I totally recommend it. Hands down, no questions asked....

Brad Averbeck wrote:
> Travis wrote:
>> For the record Equallogic rocks. It's incredibly impressive. We had
>> 9 of their arrays at my last job and they were bulletproof, incredibly
>> flexible, and easy.

>
> That's good to know. I have been looking at their stuff and it does
> look pretty nice.
>
> Brad

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

On Fri, 08 Feb 2008 14:53:46 +0000, Travis wrote:

> For the record Equallogic rocks. It's incredibly impressive. We had 9 of
> their arrays at my last job and they were bulletproof, incredibly
> flexible, and easy.


I wonder if that's going to change at all thanks to the acquistion by Dell.

--
Joe
"Those of you who think you know everything are annoying to those of us who do."

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

> I wonder if that's going to change at all thanks to the acquistion by
> Dell.


I love it when companies buy out others and then proclaim how
they are ushering in a new era..in whatever technology they acquired.
<rolls eyes>

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

On Fri, 08 Feb 2008 16:21:07 +0000, G of Borg wrote:

> I love it when companies buy out others and then proclaim how they are
> ushering in a new era..in whatever technology they acquired. <rolls eyes>


It's the Microsoft way!

--
Joe
"Those of you who think you know everything are annoying to those of us who do."

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joebrug Trusted Contributor.
Trusted Contributor.

Re: VM - iSCSI or FC?

Thanks for the comments guys. I strongly suggest taking a look at these Pillar systems (Pillar Data Systems - The First and Only True Application Aware Storage). We're probably going to get the Axiom 300, can run either iSCSI or FC. I think we're going to go with the FC with SATA drives (it says 500GB "brick", which is really 5TB usable). The company was created by Larry Ellison, who was trying to get into the storage market. Apparently they've been around for a long time, but only in the big enterprise systems. Now they've trimmed the Axiom 500 down so they can get into the midsized market, and have come out with the Axiom 300. It seems really really cool.. for one, you dont have to worry about setting up Raid configs at all, it stripes the data across all disks, with dual controllers in each 'brick'... and the QoS stuff is kinda neat. When you want to create a LUN, you go into the web management, choose a size and the 'priority' (high, medium, low, archive). It writes the 'high' data across the outter edge of the disks, so the best speed. The website confused the heck out of me.. but I've met with the guys many times. They are extremely nice and willing to come out all the time to help out. The thing that turned me off of a Dell solution is I have to have a conference call with 5 different people, because no one person knows the products... very frustrating. and it seems like going FC is not much more expensive than going iSCSI through them.. so I figure, might as well go FC.

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joebrug Trusted Contributor.
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Re: VM - iSCSI or FC?

oh, Joseph,
as far as the exposing raw LUNs to the VM's or using VMDK files.. I have absolutely no idea 🙂 talking over my head now.. I am taking the VI3 class next week though, so hopefully I'll have a better idea of what to do. We're also looking at this project through disaster recovery eyes as well.

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

> It's the Microsoft way!

There's a lot more guilty than just them.
It's like the kid next door assembling an
awesome RC plane then I buy it and tell
everyone about my awesome new creation.


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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

On Fri, 08 Feb 2008 19:26:01 +0000, joebrug wrote:

> Thanks for the comments guys. I strongly suggest taking a look at these
> Pillar systems ('Pillar Data Systems - The First and Only True Application
> Aware Storage' (http://www.pillardata.com)). We're probably going to get
> the Axiom 300, can run either iSCSI or FC.


One thing you may want to check with is talking to VMware pre-sales and
see if this is on their officially supported list for ESX. If it's not,
it doesn't mean the solution is bad, but it means if you call up VMware
they may just say "sounds storage related and we don't support your
storage." It's always best to get something they officially support.

--
Joe
"Those of you who think you know everything are annoying to those of us who do."

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joebrug Trusted Contributor.
Trusted Contributor.

Re: VM - iSCSI or FC?

oh it definitely is. Actually they are partners with AccessFlow who is one of VMWare's platinum partners and virtualization specialists who use Pillar. definitely supported. The reason I mentioned them is because you said you were looking at HP, EMC, Etc.. which is Pillar's competition

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Anonymous_User Absent Member.
Absent Member.

Re: VM - iSCSI or FC?

On Fri, 08 Feb 2008 19:56:02 +0000, joebrug wrote:

> oh it definitely is. Actually they are partners with AccessFlow who is
> one of VMWare's platinum partners and virtualization specialists who use
> Pillar. definitely supported. The reason I mentioned them is because you
> said you were looking at HP, EMC, Etc.. which is Pillar's competition


In that case... I'll have to add them into the mix of possibilities here.
Thanks!

--
Joe
"Those of you who think you know everything are annoying to those of us who do."

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