ago. I have seen no such issues in a long time.
I agree with Joe (since we tested it together) that contention on a SAN can
be a real problem and you have design with this in mind if you go for SAN
boot for any significant number of servers. Low numbers are great, actually
better than local disk, but when you start to use up the available
bandwidth, watch out (especially with iSCSI which maxes out pretty quickly
when compared with fiber channel)
Right now the available hardware is more than you can effectively use with
standard TS/XA workloads. Especially if you stick with 32bit OS you are
actually gaining more resources by carving up that new quad core 16-32GB box
rather than maxing it out with a local OS. 64bit is a different story but so
far we have virtually no 64 bit adoptions at our customer sites....
Don't' get me started about efficiency because then I will start talking
about Virtuozzo again and then Rick will start talking about the Provision
Networks broker for Virtuozzo... :)
Steve Greenberg
Thin Client Computing
34522 N. Scottsdale Rd D8453
Scottsdale, AZ 85266
(602) 432-8649
www.thinclient.net
steveg@thinclient.net
-----Original Message-----
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf
Of Joe Shonk
Sent: Friday, December 19, 2008 12:59 PM
To: thin@freelists.org
Subject: [THIN] Re: Citrix - Harddisk Specification
Ok... So it's fair to say that the Dell RAID Controllers have progressed
since the NT 4.0 days? If you end up losing the RAID set who cares? It's a
terminal server. If Fault Tolerance isn't an issue, then I would argue that
RAID 0 will give you better performance over two independent spindles.
It's not the form factor that causing the drives to fail, but the excessive
heat generated by blades/chassis. Not to mention vibrations.
Performance Hit with SAN? Yes, this thread has been through this argument.
With the right system, it's even faster. 15k SAS drives are great, except
when you factor in the crappy SAS controllers.
SSD give great performance on reads, but not much of an advantage on writes.
It all depends on your workloads.
As far as virtualization goes... Sure there is overhead. But can a single
32-bit Terminal server take advantage of a quad-core processor? Or more
likely 8-cores in box? At the moment, the hardware has outpaced the
operating system. Even with x64 system, how many users do you really want
to pack on single OS instance?
Joe
-----Original Message-----
From: thin-bounce@freelists.org [mailto:thin-bounce@freelists.org] On Behalf
Of Matt Kosht
Sent: Friday, December 19, 2008 11:58 AM
To: thin@freelists.org
Subject: [THIN] Re: Citrix - Harddisk Specification
On Fri, Dec 19, 2008 at 12:34 PM, Joe Shonk <joe.shonk@gmail.com> wrote:
> I would have to disagree... What kind of RAID controllers are you using?
If
> I experienced faulty RAID controllers like that, I would be on the phone
> with the vendor. If there is no resolution, then it's time to switch
> vendors.
Of course I have and would try to resolve such issues, but by then
it's too late... it didn't work! This was an issue with early Dell
servers I used in the past (We're talking NT 4.0). I haven't had it
since. My point was simply that no technology is bulletproof.
> Second, it's a nice idea that Autosaves and checkpoints are going to save
> the user's work.. But it's simply not practical... It doesn't work quite
> that way. Data gets losts, databases/indexes get corrupted, users get
> frustrated.
I don't disagree. My point is it may be marginally safer to run RAID
on term server, but at a direct cost to performance.
>
> If you are using blades, all the more reason to use raid. Drives placed
in
> blades have a higher failure rate.
>
I didn't know that. Why is that? 2.5" drives fail more than larger
ones? Does that still hold true of the newer blades that have SSD's?
> Personally, I'm from the boot from SAN methodology. And with most
projects
> going virtual we will see more and more of this.
Nobody has been able to sell me on boot from SAN for Term servers
specifically. Though being able to just slap in a new server and have
it boot without much setup is appealing. What kind of performance hit
is there to read/write to page file on a SAN volume vs. using a
direct attached 15K SAS?
Virtualizating a Term Server? I have thought about it, but just can't
get past 15-20% hypervisor overhead hit on something I know is going
to run full tilt disk and CPU. I also run a few test term servers on
VMWare ESX from a SAN and they run very slowly.
I have thought about getting a dual quad core with 16GB RAM , SSD's
and using a bare metal hypervisor to have 4 32 bit term servers each
dedicated with 2 VCPU's, 4GB RAM. I would do all of it locally on the
SSD's as I am thinkin that this would give the best performance. Just
on paper mind you. Anyone tried this or something similar?
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