[deanhills]

I haven't used Virtualbox since 2012.  I remember when I last used it with a Lenovo Laptop i7 Pentium, it installed fast.  And the OSs I installed on it installed similarly fast.  It was a pleasure and great fun.

So today has me baffled.  I installed Virtualbox on my Desktop.  My Desktop is a Dell Optiplex Intel Core i7 with Windows 7 Professional.  It has 16 GB RAM.  I allocated 2 GB RAM and 8 GB disk space for CentOS 7 before I loaded CentOS 7.  Installation of Virtualbox had no problem.  I tweaked the settings a little adding more video resources, etc, according to a course I've been following.

Headache started with installation of CentOS 7.  I had to re-try about six times during setup screen freezes that I couldn't get out of.  The setup windows for Date and Time, Language, Software etc took ages to load, and with each failed attempt the screen would freeze up during a different setup Window - Window was completely unresponsive - like only way I could get out was to abort the installation, remove the CentOS and start fresh.  After at least an hour of that, the installation system after setup finally came up and showed the button for installing CentOS 7, and wow, did that take forever to install.  It took AGES for the installation to complete. How come?

Then after installation, reboot, exiting, and then getting in again, it takes a long time for Linux to load.

Now I reckon if it's as painful to install it right now, that when it gets to working with it, will I have the same issues?  Is it worth it?

Does any one know what the variety of causes could be for CentOS 7 to be so slow?

Should I try a different download, or are they basically all the same from all of the distribution centers?  I downloaded the CentOS from centos.org ISO DVD - did nothing out of the ordinary.  And took a distribution from a distribution centre close to where I live.  The CentOS version I loaded is CentOS Linux Release 7.6.1810.

[rudra]

"Lenovo Laptop i7 Pentium"

what is a i7 pentium then ?

Leaving that aside, I would like to know what kind of storage are you using. Is it an hdd ? how is its health ? Crystaldiskinfo might come handy here.

I can run two VMs on an 8gb ddr4 system with g4560. that processor has like 2 core 4 thread and it is like a 6th gen i3. May be i am tolerant of slowness cause i am still using hdd in most of my work.

Yes. All the dvd or cd images are kinda same. Just like with windows. Licensing in case of windows may be different , but i doubt that has much impact on system installation speed.

Could you try installing from a ubuntu 18.10 cd may be. just to check if that installation goes same too.

I really have no idea off the top of my head.

edit:
thanks to HR for thinking about another possible source. i cant even think of running my system with vtd etc turned off. hehe. i never did. but that seems more likely for you. virtualbox is not getting direct hardware (dma/ahci ?) access and doing more virtualisation through software. it is a roundabout way of doing same things, but much slower.

[Mashiro]

Are the hardware virtualization extensions (Intel VT and alike) enabled in the BIOS/EFI/UEFI of your computer? I experienced the following with VirtualBox and other virtualization software that is using hardware virtualization. If the CPU extensions for hardware virtualization are disabled the performance of the VMs becomes really bad. Everything takes ages to load, the performance overall is bad and the CPU and SSD/HDD gets hammered at 100% all the time. Overall this causes the whole host system to become very slow and very unresponsive.

On another point: is your hard drive or SSD in a good state? Perhaps it's so slow that the I/O collapses when the VM starts doing its work. This could be a likely situation if the HDD/SSD is rather slow or in bad health state.

[deanhills]

"Lenovo Laptop i7 Pentium"

what is a i7 pentium then ?

Leaving that aside, I would like to know what kind of storage are you using. Is it an hdd ? how is its health ? Crystaldiskinfo might come handy here.

I can run two VMs on an 8gb ddr4 system with g4560. that processor has like 2 core 4 thread and it is like a 6th gen i3. May be i am tolerant of slowness cause i am still using hdd in most of my work.

Yes. All the dvd or cd images are kinda same. Just like with windows. Licensing in case of windows may be different , but i doubt that has much impact on system installation speed.

Could you try installing from a ubuntu 18.10 cd may be. just to check if that installation goes same too.

I really have no idea off the top of my head.

edit:
thanks to HR for thinking about another possible source. i cant even think of running my system with vtd etc turned off. hehe. i never did. but that seems more likely for you. virtualbox is not getting direct hardware (dma/ahci ?) access and doing more virtualisation through software. it is a roundabout way of doing same things, but much slower.

@rudra You wouldn't believe it!!!!!  Those mirror distribution downloads from centos.org were faulty.  I still can't believe it!  How come someone hasn't fixed it yet? This is the CentOS up to date download from centos.org ISO DVD mirror site - like the official site - that I was trying to work with:
CentOS-7-x86_64-DVD-1810

Like I tried at least three different mirror repositories - spent hours over them.  I also changed from my desktop computer to a very old ThinkPad laptop that I hadn't used in a very long time.  It has 8GB RAM and I added more RAM to Virtualbox - 3.5GB RAM.  Created dyanmic disk of 90GB in Virtualbox as I have lots of space in the laptop. That didn't make much of a difference to my negative experiences with downloading CentOS in Virtualbox - just slightly faster than it had been in the Desktop. 

Then finally after many hours decided to go for a minimal download (now working on the laptop) as I thought I'd save time and then manually add some of the features that the course required, and that was when the Linux let me know that it can't do it as there was a mistake with the repository.  You can check the error in the discussion below, as that is the identical error message I got.  When I Googled the error message I got my answer:
https://www.centos.org/forums/viewtopic....48&t=66998

I then tested this and looked for an earlier download of CentOS - like a specific one that was mentioned in distrowatch after I googled for the same version as the one the course presenter had used - this was the closest one I got:
https://distrowatch.com/?newsid=08871

CentOS-7-x86_64-DVD-1503

The download the course presenter was working with was 1511.

And then everything with Virtualbox and the download worked as it should have worked!  Exactly as in the course Video.  Not lightning fast of course.  As it's a big download.  But everything responded as it should have responded.  And I ended up with what I should have with the up to date download.  A successful download and installation in Virtualbox.

Am wondering also if CentOS download has become too big?  Like I'll never know, as I'm not going to try the upload from a mirror repository ever again.  Not after this last experience.

Anyway, dead tired now, and obviously I need to update the distribution, but possibly that will come through the course anyway.  Maybe next weekend.

---

Are the hardware virtualization extensions (Intel VT and alike) enabled in the BIOS/EFI/UEFI of your computer? I experienced the following with VirtualBox and other virtualization software that is using hardware virtualization. If the CPU extensions for hardware virtualization are disabled the performance of the VMs becomes really bad. Everything takes ages to load, the performance overall is bad and the CPU and SSD/HDD gets hammered at 100% all the time. Overall this causes the whole host system to become very slow and very unresponsive.

On another point: is your hard drive or SSD in a good state? Perhaps it's so slow that the I/O collapses when the VM starts doing its work. This could be a likely situation if the HDD/SSD is rather slow or in bad health state.

I think you must have hit the problem with why my desktop is underperforming.  I'm sure if I check up on hardware virtualization extensions I'll be able to make things faster.  When I did the Distrowatch distribution of 2015 instead, I used my   old ThinkPad X201 - had to recharge it (the charging cable hasn't been working well for a while and you have to wiggle it to get it to work ) but wow does this laptop respond fast.  It is also i7 but less RAM - 8GB RAM.  However, there must be something with my desktop, as this laptop responds faster with the 8GB than my 16GB RAM of my desktop so what you say must be true.  I've always wondered whether my Desktop was slow and that the addition of 8GB RAM at end of 2016, was not really making a difference to the speed - I had it "professionally" done.  Maybe it wasn't configured properly, so I'll check up all of your tips above.

So what I did when I started using the laptop instead of my desktop (after about the fifth try), was to allocate more RAM for Virtualbox.  I made it almost 4GB RAM and a dynamic hard disk of 90GB.  But who knows, that may not even have been necessary.  The whole problem was the darn faulty repositories.  Who could ever have thought that to happen?

I'm now going to go back to the Desktop and see how it responds with the same 1503 CentOS 7 download.  Maybe next weekend.

BTW, while I was on the Laptop and still having problems with that 1810 CentOS Repository download, I decided to try the Microsoft Windows Virtual PC that should technically be good to work with with Windows 7 Professional - the OS of my laptop and also my desktop.  I tried that in between all of my other efforts, and that was not working at all.  Like current distros probably can't work on Windows Virtual PC any longer.

Anyway, I've now had joy with getting everything to work as it should.  Virtualbox I now have more faith in.  I've lost all faith in the centos.org mirror repositories.  But by repeating the downloads probably at least 12 or more times, I've learned a LOT.  Hopefully I've now learned that all is not perfect with my Desktop RAM either.  

With the desktop RAM when I got the Desktop in 2014, it had 8 GB RAM, but it was set up by the guys who sold it to me for 32bit instead of 64.  So my desktop was only using 4GB of the 8GB RAM.  I have 500GB standard Hard Disk.  Then I had the disk reformatted by a Technician, and gave him 8GB additional RAM to add.  He probably didn't configure it properly as I didn't feel that much difference even from the 4GB RAM that I originally had on 32 bit.  So I guess there's much room for improvement in the setup in the BIOS.  Probably need to make some backups first though before I go that road. Better yet, maybe I should take it to another technician to fix it properly.  Canada was Dell country at one time, maybe they can still do wonders to a PC even though it's grown into a Laptop environment predominantly.