Xen Server 6.5 + Xen Orchestra w. HA & SAN
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@ntoxicator said:
This would be the DRBD interface / IP link between the two(2) nodes
DRBD is the protocol there, no iSCSI. It's not SAN or anything like that.
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Ok. Their documentation says the DRBD interface to be bonded from within Xencenter (per documentation). Am I wrong here?
So the ethernet link between the two nodes, im sure GigE is plenty enough bandwidth? or 10Gige not hurt?
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@ntoxicator said:
Ok. Their documentation says the DRBD interface to be bonded from within Xencenter (per documentation). Am I wrong here?
So the ethernet link between the two nodes, im sure GigE is plenty enough bandwidth? or 10Gige not hurt?
Well 10 Ge never hurts...
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@ntoxicator said:
Ok. Their documentation says the DRBD interface to be bonded from within Xencenter (per documentation). Am I wrong here?
That seems fine. DRBD works differently than iSCSI. They are not related protocols.
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@ntoxicator said:
So the ethernet link between the two nodes, im sure GigE is plenty enough bandwidth? or 10Gige not hurt?
What is the bandwidth of the storage? You will be limited to GigE throughput speeds, that's 1Gb/s, for writes. That's a fraction of what SATA and SAS can do.
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Are you sure that all of this makes sense in your environment? This is two orders of magnitude from where you have been in the past. It isn't normal to have an LA (low availability) environment and get by for a long time and suddenly leap to HA. Why not just go to standard availability? It's a full order of magnitude safer than where you have been in the past, almost zero effort (and no risk from that lack of effort... simple is your friend) and less than half the price of doing HA.
SA is the only clear win... tons safer, tons cheaper. HA is tons safer for sure, but costs more and doesn't make sense given what was deemed acceptable in the past.
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Looking to develop hardware costs and quotes for new equipment. Company wants to grow employee's to 500+ by year 2020. Need to have reliable servers hosting VM's
If the primary xenserver host fails.. then what? We have a day + of downtime waiting for server to come back online?
Looking to future proof so can be in production for next 5 years. I may not be here with company in next 5 years, so want to leave behind a good setup.
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@scottalanmiller said:
Are you sure that all of this makes sense in your environment? This is two orders of magnitude from where you have been in the past. It isn't normal to have an LA (low availability) environment and get by for a long time and suddenly leap to HA. Why not just go to standard availability? It's a full order of magnitude safer than where you have been in the past, almost zero effort (and no risk from that lack of effort... simple is your friend) and less than half the price of doing HA.
SA is the only clear win... tons safer, tons cheaper. HA is tons safer for sure, but costs more and doesn't make sense given what was deemed acceptable in the past.
also to mention, I've been hammering HA setup for awhile to management; for peace of mind and rest-easy at night. Yes, we've been getting along with low availability type setup for now. But as the resource usages increase; i feel the need for HA setup with dual nodes.
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@ntoxicator said:
Looking to develop hardware costs and quotes for new equipment. Company wants to grow employee's to 500+ by year 2020. Need to have reliable servers hosting VM's
That's fine. But that doesn't suggest HA at all.
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@ntoxicator said:
If the primary xenserver host fails.. then what? We have a day + of downtime waiting for server to come back online?
This is not how you discuss risk. This tells me that HA is not needed. This isn't how a "we need HA" discussion would start.
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@ntoxicator said:
Looking to future proof so can be in production for next 5 years. I may not be here with company in next 5 years, so want to leave behind a good setup.
This strongly says that HA is a bad idea as it requires a lot more skill, documentation, knowledge, etc.
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@ntoxicator said:
But as the resource usages increase; i feel the need for HA setup with dual nodes.
Resource utilization does not lead directly to needing higher availability. Wall St. firms don't need HA on billion dollar trading systems, why do you feel that moving to 500 users warrants in for you but hundreds of thousands of users does not warrant it for them?
That's not to say that HA can't be right for you, I'm saying that you aren't thinking about it in the way that you should if you were going to determine that HA was needed.
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@scottalanmiller said:
@ntoxicator said:
Looking to future proof so can be in production for next 5 years. I may not be here with company in next 5 years, so want to leave behind a good setup.
This strongly says that HA is a bad idea as it requires a lot more skill, documentation, knowledge, etc.
And if HA is determined to be needed, it needs to be an appliance, not a solution that they will be unable to support.
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Server planning for five years out is relatively risky. Not bad, but we know just about nothing about the future. And "the company wants to grow" should not lead us to spending today. A 200 person company buying hardware like they are a 500 person company is the hallmark of a company that is never going to get to 500. Projections like that are not things that IT acts on, that would lead to some dangerous stuff.
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Ok, why dont you come consult for us then? Explain why HA is not needed and list the negatives and upside.
I dont get why your so anti-HA?
So we get another single server, spec'd full of drives and hope that we dont have a hardware failure
What are chances of mobo dying on Dell R730? or integrated NIC card failing, etc? I suppose low percentage rate.
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CEO/CFO & management, will not purchase new hardware unless they're certain it'll last for 5+ years and handle the load of 500+ employee's by year 2020. All by company projections and their hiring needs/growth rate statistics.
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@ntoxicator said:
I dont get why your so anti-HA?
I "pro-good business decisions", if that sounds anti-HA, it is self explanatory.
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@ntoxicator said:
Ok, why dont you come consult for us then? Explain why HA is not needed and list the negatives and upside.
That's what I do for a living, I help CEOs and CFOs understand how finances play into IT and help steer companies away from exactly these kinds of problems. I specifically am the person who does this, that's my focus.
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For HA, two nodes.
It comes down to understanding the hardware and the MTBF? Understanding the common failures of said server/generation/caveats?
Understanding risk or percentage change as to an actual hardware failure which would result in a node going down, and the need for fail-over scenerio
I see those as logical talking points and reasoning when looking at HA and if its a need or not
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@ntoxicator said:
So we get another single server, spec'd full of drives and hope that we dont have a hardware failure
Well, that is WAY better than where you are today, right? It would...
- Save you a ton of money.
- Improve your reliability by a full order of magnitude.
- Be far easier to maintain.
- Not waste money that might be needed for growth.
- Allow you to get a decent support contract.
- Be easily able to be handed off to an MSP or your replacement someday.
- Not require that your shop develop and maintain indefinitely more skills than it otherwise needs.
