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Design Exercise-Fixing Old or Mismatched Clusters

In two previous posts, I talked about some design examples I’ve seen:

Design Exercise – Scaling up vs Scaling out

Design Exercise – DR Reuse

Today I’m going to talk about the “No problem, we’ll just add a host” problem.  But not in the “one more of the same” scenario, instead a “we can’t get those any longer, so we’ll add something COMPLETELY different” scenario.

Regardless of if the current site is something like previously described with matching systems (eg: 4x Dell PE2950’s) or random systems, often when capacity runs out, budget is likely low, and so the discussion comes up to “Just add a host”. But as we know from previous examples, adding additional hosts costs money for not only hardware, but licences. I have two different example sites to talk about:

Example 1:

  • 4x Dell PE2950, 2x 4 Core, 32GB RAM, 4x 1GBE hosts

Example 2:

  • 1x Dell T300, 1x 4 Core, 32GB RAM, 2x 1GbE
  • 1x HP DL380 G6, 2x 4 Core, 64GB RAM, 4x 1GbE
  • 1x Dell R610, 2x 6 Core, 96GB RAM, 4x 1GbE

In both cases, we’ll assume that the licencing won’t change as we’re not going to discuss actually adding any hosts, so all software/port counts remain the same.

As you can see, neither environment is particularly good. They both old, but Example 2 is horribly mismatched. DRS is going to have a hell of a time finding proper VM slots to use, the capacity is mis-matched, and nothing is uniform. The options to fix this all involve investing good money after bad. But often an environment that is this old or mismatched, likely ended up this way due to lack of funds. We can talk about proper planning and budgeting until we’re blue in the face, but what we need to do right now is fix the problem. So let’s assume that even if we could add or replace one of the hosts with something more current, like your $7000 R620 with 2x 6 Core and 128GB, this is not in budget. Certainly, 3-4 of them is not, and certainly not for the bigger/better systems at $10K+.

So what if we go used? Ah, I can hear it now, the collective rants of a thousand internet voices. “But we can’t go used, it’s old and it might fail, and it’s past it’s prime”. Perhaps – but look at what the environments currently are. Plus, if someone had something ‘newer’, that they’d owed for 2 years into a 3-5 year warranty, it would be “used” as well, no? Also, accepting for complete and spontaneous host failures, virtualization and redundancy gives us a lot of ways to mitigate actual hardware failures. Failing network ports, power supplies, fans, etc, will all trigger a Host Health alert. This can be used to automatically place the host in Maintenance Mode and have DRS evacuate it and send you an e-mail. So yes, a part may fail, but we build _expecting_ that to be true.

Now assume that the $7000 option for a new host *IS* in budget. What could we do instead? We certainly don’t want to add a single $7000 host to the equation, for all the reasons noted. Now we look into what we can do with off-lease equipment. This is where being a home-labber has its strengths – we already know what hardware is reliable and plentiful, and still new enough to be good and not quite old enough to be a risk.

What if I told you that for about $1500 CAD landed, you could get the following configuration:

Example 1 can now, for around $6000 CAD, replace all 4 hosts with something newer, that will have 16 more cores, and 4x the RAM. It’s not going to be anywhere near the solution from the other day with the 384GB hosts – but it’s also not going to be $40K in servers. Oh, plus 8U to 4U, power savings, etc.

Example 2 is able to replace those first 2 hosts and standardize, for around $3000.

In either case, they’re still “older” servers. A Dell R610 is circa 2009-2012, so you’re still looking at a 2-5 year old server at this point – which might be a little long in the tooth. But if the power is enough for you, and you’re just trying to add some capacity and get out of “scary old” zone, it might not be so bad. Heck, either of these sites are likely going to be very happy with the upgrades. Questions will need to be answered such as:

  • Lifespan – how long are we expecting these servers to be a solution for? Till the end of next calendar year or about 16-18 months? That’s fine.
  • Budget – are we doing this because we have run out of budget for this year but *NEED* “something”? Has next year’s budget been locked away and this was ‘missed’, but you still need ‘something’?  If we assume these are 18 month solutions, to get us from now (Oct 2014) to “after next budget year” (Jan 2016), then Example 1 is $333/month and Example 2 is $167/month. Money may be tight, but that’s a pretty affordable way of pushing off the reaper.  Heck, I know people with bigger cell phone bills.
  • Warranty – these may or may not come with OEM warranty. Are you okay with that? Maybe what makes the most sense is just pick up an extra unit for “self-warranty” – it is almost certainly still cheaper than extending the OEM warranty. Remember though, OEM support also helps troubleshoot weird issues and software incompatibilities, etc. Self-warrantying just gets you hard parts, that you can swap – if you have time and energy to do so. Check if the secondary market reseller will over next day parts, that may be sufficient for you. Also, check if the vendor of the hardware you’re choosing will allow you to download software updates (eg: management software, firmware, BIOS, etc) without a service contract. Dell, at this point, still does, which is why I like them (for customers and my lab).  Oh, an advantage of the extra unit for “self-warranty”?  You can use it for Dev/Test, learning, testing things you want to try, validating hardware configurations, swapping parts for testing suspected issues, etc.
  • Other Priorities – do you need to spend the same money you’d spend on new hosts, elsewhere? Maybe you need a faster SAN today, because you’re out of capacity as well, and you have to make a choice. You can fix it next year, but you can’t fix both at once, regardless of effort or good intentions. Maybe you want to go to 10GbE switches today in preparation. Perhaps you want to spend the same money on training, so that your staff can “do more with less” and have “smarter people” instead of “more thingies, with no one to run them”.

I fully realize that off-lease, eBay, secondary market is going to throw up automatic “no’s” for a lot of people. Also, many management teams will simply say no. Some will have an aversion to “buying from eBay” – fine, call the vendor from their eBay auction, and get a custom quote with a PO directly, and but it just like you would from any other VAR. The point of the matter is, you have options, even if you’re cash strapped.

BTW, if anyone was thinking “why not just get R620’s” which are newer, you certainly could – http://www.ebay.ca/itm/DELL-POWEREDGE-R620-2-x-SIX-CORE-E5-2620-2-0GHz-128GB-NO-HDD-RAILS-/111402343301?pt=COMP_EN_Servers&hash=item19f018db85. One can get an R620, 2x 6 Core E5-2620, 128GB RAM (16x8GB almost certainly, but 24 DIMM slots), 4x 1GbE, iDRAC, etc, for about $3000. This would give you more room to grow and is newer equipment, but it starts getting much closer to the $7000 configuration direct from Dell with 3 year warranty, 10GbE ports, etc. Still, 4x $3K is much less than 4x $7K, and $16,000 is a lot of money you could spend on something else. Just watch you’re not paying too close to retail for it to be not be worth it.

The trick, coming from a home-lab guy, is to be “just old enough to not be worth any money to someone else” but “just new enough to still be really useful, if you know what you’re doing.”

Also, consider these options for the future.  Remember that ROI involves a sale.  Let’s say you purchased the brand new $7000 servers and made it 5 year warranty vs 3 year for… 20% more or about $8500.  You’re almost certainly not going to use it for 5 years.  But in 2.5 years, when you want to put that server on the secondary market, and it still has 2+ years of OEM warranty left – you’re going to find it has significantly more resale value.

This is no different than leasing the ‘right’ car with the ‘right options’, because you know it’ll have a higher resale value at the end of the lease.  If you’re the kind of person that would never “buy new, off the lot” and would always buy a “1-2 year old lease-return, so someone else can pay the depreciation” – this solution is for you.

If in one scenario you haul the unit away to recycling (please, call me, I offer this service for free Smile), and another you sell the equipment to a VAR for $2000/unit you can use as credit on your next purchase or services…

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Categories: Dell, Design, Hardware, VMware, vSphere
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