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New toy and migrating Linux to new host

Discussion in 'Technology Advice' started by ChoiAndJohn, Dec 22, 2020.

  1. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    For the technical here who are into this sort of thing like @oss thought I would share a pic of my new toy in the study and ask if anyone has experience migrating a physical Ubuntu instance to a vmware esxi instance without rebuilding from scratch.

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  2. oss
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    oss Somewhere Staff Member

    That's what I am aiming for when I retire, my server cabinet will reside in Scotland while I roam the world :D

    We run our systems on ESXi with a rack similar to yours but a bit larger, good way to heat the next room btw :D

    I don't have any personal experience of virtualising an Ubuntu instance but I am certain it could be done, about 12 years ago we virtualised a number of Windows servers which worked well but since then everything has been a new install of a VM instance from scratch, we run a lot of them.

    Most of our customers are on ESXi now but it is surprising how much trouble some sites have with their server configuration, and that's not a criticism of ESXi it is a superb platform.

    edit: I take it that is a storage array at the top of the cabinet?
    Last edited: Dec 22, 2020
  3. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    Yeah I know most people just bite the bullet and install from scratch. I virtualized a windows imstance a while back. Well it's not a SAN array using iscsi it's a NAS. Although I'm running a ups as you know you really need everything rock solid for iscsi without problems and I tinker too much. Nas is safer. I have my local network split into a 10gbe over fiber subnet for storage and 1gbe over cable for bog standard clients. Those two dell servers have 48 and 56 cores respectively with their own sas arrays onboard for hosting the vms I run. I have about 40 vms or so. Nothing compared to a commercial environment but still adequate for my own use and experimenting..
  4. oss
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    oss Somewhere Staff Member

    That's quite a system :D

    Not sure if we even have that many cores in our very new Dell Servers :D

    I like the idea of the 10gbs fibre subnet for data, but is your NAS using solid state drives or spinning disks?
  5. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    It's
    It uses an SSD cache. The main array is raid 6 and currently has 6x10tb giving about 40tb usable. The max read and write performance I get is about 1Gigabyte per second. It's useful for me because I mount the nas remotely on my workstation and frequently copy large files. The nas is also mounted on some of the vms that need access to the data on it. Only fly in the ointment is the hp procurve datacentre switch. Has 10gbe sfp+ ports and uses more power than both servers. Ouch. :)
  6. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    Oh + those cores include the xeon hyperthreaded cores. Physical cores the servers have 24 and 28 respectively but as you know the always run out of ram and disk space first. I only have 192gb ram in each. :D
  7. oss
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    oss Somewhere Staff Member

    I did say it would keep a room hot :D

    I don't have direct experience of kit like that these days, although I've recommended HP switches and other hardware to clients in the past.

    Our MD is the network specialist now, I deal more with the practicalities of using the available bandwidth be it memory, database in memory, intranet and extranet communications as I am an applications programmer and at this end of my career it's the understanding of bottlenecks in application design that matters to us, however saying that our systems although Enterprise level are not really up there at Global Enterprise level :)
  8. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    In my professional life, likewise. I just like to manage my own hardware at home. Run a mail server, Web hosting, git, jira, confluence, Jenkins, dev, test and prod servers and so on for my own work or when I'm working freelance.
  9. oss
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    oss Somewhere Staff Member

    That's more than we run the business on as well :D

    Hyperthreading and huge numbers of cores is all very well as long as the applications are sufficiently parallel to use it, in reality you will likely have used ESXi to allocate a limited number of cores to individual VMs.

    Operating systems can certainly make good use of those cores but even now, outside some complex science applications, there are few day to day apps that make real use of that power.

    From memory John you were in the financial sector so I guess you could have some complex modelling applications running?
  10. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    Absolutely. You allocate cores to vms depending on what they need. Once a vm is running it doesnt get to demand more cores or anything. Typically in a virtual environment you oversubscribe cores so it's OK to have say 15 servers with 4 cores allocated each (60 allocated) even though you might actually only have 30 physical cores. It's unlikely every machine will be using 100 percent cpu all the time at the same time so you're looking to get your physical host at say 80 percent utilisation with enough headroom for spikes.
  11. oss
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    oss Somewhere Staff Member

    We used Confluence in the past but not so much now, the company moved mail out to O365, we use Git but mostly through Azure DevOps, but I am thinking of hosting Azure DevOps internally in the near future, we still use Jenkins but the build pipeline is mostly via SVN we don't do automatic builds via DevOps, that's another reason for maybe moving DevOps in-house more of a trust thing really.
  12. oss
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    oss Somewhere Staff Member

    Yes indeed, the best way to get value from the processing power you have available.

    edit: and a great way to keep the heating on ;) :D
  13. ChoiAndJohn
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    ChoiAndJohn Well-Known Member Trusted Member

    Yes.. The rack heats a large room. It's not as wasteful as it sounds because at least my hobby is reducing the heating bill. By the time you add up the cost that I would need to pay to subscribe to cloud services and outsource it all, it would cost more money and be less secure. I like the security of knowing that my material isn't out there at the mercy of some external party. I never use cloud for my own stuff if I can help it.
  14. oss
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    oss Somewhere Staff Member

    Oh I don't think it is wasteful at all John, I think this is good use of computers :D

    I agree completely about knowing where my data is but I am not worried about cloud solutions as long as they are zero knowledge encrypted and as long as it is a replication system where I have an encrypted copy locally.

    There's no way you could get 40 good performing VMs in he cloud for any reasonable price, I do agree!

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