RAM recommendation for logos in virtual machine

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Posts 7
Steven Luethy | Forum Activity | Posted: Mon, Jun 8 2020 8:50 AM

I need a new computer and change from Windows to Linux. I want to use logos in a virtual machine in the future. How much RAM is recommended for Logos in a virtual machine?

Logos recommends 16 GB of RAM for a computer. In my case, is 16 GB RAM recommended for Virtualbox only? Or is 16 GB RAM enough for the entire computer with Linux, Virtualbox, and Logos? How can I estimate the amount of RAM required?


Thanks in advance for your support

Posts 2583
Lee | Forum Activity | Replied: Mon, Jun 8 2020 9:06 AM

Ideally you'd want to allocate about 16GB to the virtual machine. You can try it with 8GB and move up.

Caution: if you're running a VM, even if it's an SSD the Windows guest VM may run I/O as if it's a hard disk. This wears out the SSD faster.

Posts 2442
mab | Forum Activity | Replied: Mon, Jun 8 2020 4:27 PM

I think this is probably just asking for trouble. If I needed a Linux machine, I would confine myself to running the Logos Web App. Logos desktop is still a bit too much of a pig on resources to run well virtually on less than a real decked out machine. I think a dual boot machine would be a better alternative if that's possible. 

The mind of man is the mill of God, not to grind chaff, but wheat. Thomas Manton | Study hard, for the well is deep, and our brains are shallow. Richard Baxter

Posts 2583
Lee | Forum Activity | Replied: Mon, Jun 8 2020 9:06 PM

Dual boot is a good idea. A VM will probably run into severe performance issues even though the RAM is adequate.

Posts 408
Kevin | Forum Activity | Replied: Tue, Jun 9 2020 1:30 AM


A VM will probably run into severe performance issues even though the RAM is adequate.

I am interested why do you think this? I run Logos in a virtual machine perfectly well.

I would highly suggest you look at Qemu. If you use virt-manager it is just as easy to configure as virtualbox, although will take following a guide initially. https://help.ubuntu.com/community/KVM/VirtManager

Not only does it run at near native speeds with virtualization enabled in bios/uefi, you can even optimise  further by directly passing through hardware direct from the host, including ssds and even dedicated gpus.

Definitely worth the time to learn this, and there is lots to learn as it is so configurable.

Posts 2583
Lee | Forum Activity | Replied: Tue, Jun 9 2020 1:37 AM

Two reasons why the OP's VirtualBox solution would be sub-optimal:

1. Logos is heavily I/O dependent.
2. The disk driver layer identifies as physical AHCI drive. Even if you run off an NVME SSD, a Windows guest would not write as fast, or optimize as well, e.g. no TRIM.

Your idea of a passthrough is very good if it works.

Posts 408
Kevin | Forum Activity | Replied: Tue, Jun 9 2020 1:44 AM

Virtualbox was definitely slower for i/o, and also if i recall correct did not use all the cpu optimisation so that was slower also.

There are several different disk types that can be used, I use static size raw images but you can use virtio-scsi so that Windows sees the drives as thin provisioned drives for trim.

I have not looked tried/benchmarked all the options, but that is only because I can just tell from using it that it is very close to native performance.

I highly recommend looking at qemu, I think you might be really surprised by the performance.

Posts 2583
Lee | Forum Activity | Replied: Tue, Jun 9 2020 1:46 AM

Thanks for that. I'm not so savvy with the latest developments.

Perhaps you could follow this thread and guide further discussion. 

Posts 408
Kevin | Forum Activity | Replied: Tue, Jun 9 2020 1:48 AM

Sure will do Yes

Steven, Logos runs perfectly well on my VM when I assign 8GB to it, however there are some slight performance gains when Logos detects 12GB or more. Having said that, other than for a complete re-index, I could not notice them. See Bradley's posts on https://community.logos.com/forums/t/177457.aspx?PageIndex=3

Posts 7
Steven Luethy | Forum Activity | Replied: Tue, Jun 9 2020 2:19 AM

Thank you very much for the feedback.

Thanks for the note for Dual Boot. - I prefer a solution with a virtual machine. (An advantage of Dual Boot is the direct access to the hardware. - A virtual machine provides simultaneous work with two systems, no boot manager, no different partitions and possible conflicts between Linux and Windows).

Kevin, thanks for the experience with the 8 GB RAM, the reference to QEMU and the hint that indexing requires a lot of RAM. I suppose in this case 16 GB RAM would be enough for the whole computer at most?

Posts 408
Kevin | Forum Activity | Replied: Tue, Jun 9 2020 4:03 AM

The indexing will work fine with 8GB of ram, it will be slower, but it should not be often that you have to reindex everything thankfully, so not really an issue. For regular occasional new resource installs, the indexing is so quick that again not such an issue.

16GB should be enough for the PC, but I don't know what else you will be using the computer for. If you start running databases or doing video production you may have issues. I would split 8GB for the host and 8GB for the guest, internet/music etc on host and Logos on guest. I would make available all my logical cpus to the guest. I have experimented with CPU pinning, where you reserve specific cores for the guest, hiding them from the host, however this only led to everything being slower on both. It is rare that I will be doing something CPU intensive whilst also using Logos.   

There are some perfomance improvements from using a QXL display device rather than VGA, and setting the storage to virtio, however the required drivers, whilst digitally signed by RedHat, are not WHQL signed, so you will need to disable secureboot to use them. You can get them from https://docs.fedoraproject.org/en-US/quick-docs/creating-windows-virtual-machines-using-virtio-drivers/. If you do create a machine using virtio storage there is a virtual floppy drive image available at that page so you can install the driver during windows install.

One issue that may be a deal breaker for QXL, if the spice guest-agent service that is required for host-guest clipboard sync is enabled, the mouse cursor in the virt-manager spice viewer will disappear. I have not really looked into it much as does not interfere with workflow. I browse the internet in the guest for things I am working on there, and can copy/paste as normal in the machine, but something to consider. This only seems to occur if a secondary display device is passed into the guest. By default qxl and the clipboard sync work fine.

Using RAW as a storage format has very slight performance benefits over qcow2, however qcow2 has benefits such as snapshotting, encryption, space recovery https://techpiezo.com/tech-insights/raw-vs-qcow2-disk-images-in-qemu-kvm

I played lots initially and built several machines learning/optimising each time, you can install Windows from an iso in 15 minutes these days so not a huge drama.

I will keep eye on thread if there are more questions although might be few hours between responses if working.

Posts 2583
Lee | Forum Activity | Replied: Sun, Jul 5 2020 5:26 PM

Steven, if you're still following, you could try setting the "solid-state drive" while creating your VDI

Posts 849
Bill Anderson | Forum Activity | Replied: Sun, Jul 5 2020 7:50 PM

Steven, there's a lengthy thread here that chronicles getting Logos installed in Ubuntu derivatives through wine. I have linked to the last page. I suggest working backward from the last page instead of from the beginning.

I have Logos running in a virtual machine on my windows desktop right now with 16GB RAM dedicated to the VM in Ubuntu 20.04, so if you were running this on bare metal I am sure it would run well.

Here is a Google Doc on one way to install it. There is an app image as well, but I haven't tried that.

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