I would like to check my RAM configuration.
I know it is easy to check the total RAM installed on a computer (eg 32 GB), but is there an easy way to check in Windows if the RAM is e.g. 2x16 GB, 4x8 GB, 8x4 GB or 16x2 GB?
Thank you
There is a simple utility called CPU-Z that will tell you almost anything you need to know, check it out at http://www.cpuid.com/softwares/cpu-z.html. I do not believe there is a similar way to see this information from Windows itself.
If you have access to it, you can usually see this information in the BIOS as well.
Related
Which is the maximum amount of memory one can achieve in .NET managed code? Does it depend on the actual architecture (32/64 bits)?
There are no hard, exact figure for .NET code.
If you run on 32 bit Windows; your process can address up to 2 GB, 3 GB if the /3GB switch is used on Windows Server 2003.
If you run a 64 bit process on a 64 bit box your process can address up to 8 TB of address space, if that much RAM is present.
This is not the whole story however, since the CLR takes some overhead for each process. At the same time, .NET will try to allocate new memory in chunks; and if the address space is fragmented, that might mean that you cannot allocate more memory, even though some are available.
In C# 2.0 and 3.0 there is also a 2G limit on the size of a single object in managed code.
The amount of memory your .NET process can address depends both on whether it is running on a 32/64 bit machine and whether or not it it running as a CPU agnostic or CPU specific process.
By default a .NET process is CPU agnostic so it will run with the process type that is natural to the version of Windows. In 64 bit it will be a 64 bit process, and in 32 bit it will be a 32 bit process. You can force a .NET process though to target a particular CPU and say make it run as a 32 bit process on a 64 bit machine.
If you exclude the large address aware setting, the following are the various breakdowns
32 bit process can address 2GB
64 bit process can address 8TB
Here is a link to the full breakdown of addressable space based on the various options Windows provides.
http://msdn.microsoft.com/en-us/library/aa366778.aspx
For 64 bit Windows the virtual memory size is 16 TB divided equally between user and kernel mode, so user processes can address 8 TB (8192 GB). That is less than the entire 16 EB space addressable by 64 bits, but it is still a whole lot more than what we're used to with 32 bits.
I have recently been doing extensive profiling around memory limits in .NET on a 32bit process. We all get bombarded by the idea that we can allocate up to 2.4GB (2^31) in a .NET application but unfortuneately this is not true :(. The application process has that much space to use and the operating system does a great job managing it for us, however, .NET itself seems to have its own overhead which accounts for aproximately 600-800MB for typical real world applications that push the memory limit. This means that as soon as you allocate an array of integers that takes about 1.4GB, you should expect to see an OutOfMemoryException().
Obviously in 64bit, this limit occurs way later (let's chat in 5 years :)), but the general size of everything in memory also grows (I am finding it's ~1.7 to ~2 times) because of the increased word size.
What I know for sure is that the Virtual Memory idea from the operating system definitely does NOT give you virtually endless allocation space within one process. It is only there so that the full 2.4GB is addressable to all the (many) applications running at one time.
I hope this insight helps somewhat.
I originally answered something related here (I am still a newby so am not sure how I am supposed to do these links):
Is there a memory limit for a single .NET process
The .NET runtime can allocate all the free memory available for user-mode programs in its host. Mind that it doesn't mean that all of that memory will be dedicated to your program, as some (relatively small) portions will be dedicated to internal CLR data structures.
In 32 bit systems, assuming a 4GB or more setup (even if PAE is enabled), you should be able to get at the very most roughly 2GB allocated to your application. On 64 bit systems you should be able to get 1TB. For more information concerning windows memory limits, please review this page.
Every figure mentioned there has to be divided by 2, as windows reserves the higher half of the address space for usage by code running in kernel mode (ring 0).
Also, please mind that whenever for a 32 bit system the limit exceeds 4GB, use of PAE is implied, and thus you still can't really exceed the 2GB limit unless the OS supports 4gt, in which case you can reach up to 3GB.
Yes, in a 32 bits environment you are limited to a 4GB address-space but Windows claims about half. On a 64 bits architecture it is, well, a lot bigger. I believe it's 4G * 4G
And on the Compact Framework it usually is in the order of a few hundred MB
I think other answers being quite naive, in real world after 2GB of memory consumption your application will behave really badly. In my experience GUIs generally go massively clunky, unsusable after lots of memory consumptions.
This was my experience, obviously actual cause of this can be objects grows too big so all operations on those objects takes too much time.
The following blog post has detailed findings on x86 and x64 max memory. It also has a small tool (source available) which allows easy easting of the different memory options:
http://www.guylangston.net/blog/Article/MaxMemory.
I am using Centos 7 on the host, and with QEMU emulation windows server, I create a 15 GB disk, then after a week or so, the disk goes to 30 GB, is there a way to stop this? I am using snapshots. Is there any windows service that may be creating lots of files, or maybe the HD is being used as RAM to imprive system? from 15 GB to 30 is a lot, and the server's HD is not bigger, so It's a big issue to me. I reinstalled all and turned a lot of things off, but the same thing happens again. Little help here.
You don't mention what kind of disk image you're using, and what its configuration is. I'm guessing from your description that its a qcow2 image, since you mention use of snapshots. Snapshots stored inside the qcow2 image will increase its size beyond that visible to the guest OS. eg if you create a qcow2 image that has a virtual disk size of 15 GB, then it is possible for it to consume much more than 15 GB on the host if you have saved multiple different snapshots in the image and the guest has been writing alot of data between each snapshot. Even when snapshots are deleted, this space consumed by qcow2 won't be released back to the OS normally. So while seeing 30 GB of usage sounds quite large it is not totally unreasonable if using snapshots alot.
Currently I develop on an extremely powerful machine: Pentium i7, 32 GB Ram, SSD, 1 Gb 1028-bit graphics card, etc.
What I'm trying to figure out is the proper way to test my applications and web pages simulating a less powerful computer. Is there any way to simulate a slower processor, less ram, slower hard drive, and weaker graphics card? I'm not sure if I missed anything else in terms of what else to simulate...
The only thing I've figured out so far is resolution, but that was as easy as changing my monitor resolution. Though, if there is a way to simulate less resolution without needing to change my actual screen resolution as well, that'd be great.
Download Windows Virtual PC.
And test you application in it. You can customize your configuration, everything like disk storage, ram memory etc.
Good application for application developers to test in different environments.
I suppose you could create a virtual machine on your computer. You could then vary how much RAM & processing power it has access to. You could boot this machine of a USB drive if you wanted to simulate a slower drive.
Excuse me for my lack of knowledge but I am really new to the Virtual world and have a few questions.
I work for a small charity who specialise in providing basic IT training. We have recently acquired a few Dell Poweredge 2650 servers and Dell desktops and we wish to offer both XP, Windows 7, Mac and Ubuntu training. I am looking at setting up a Virtual environment so that we can have a standard image for each OS (I currently use image files but it currently takes approximately 25mins to build each machine and multi-boot is not an option as the new machines have 20Gb disks).
The servers are all dual processor and we can purchase more memory(I need to justify the cost)
What are the memory requirements for
the Host?
How many VM's can I run
per server?
Can I run multiple instances of the same VM
Thanks in advance for your knowledge.
Darryn
You might be able to get away with a multi-boot option with those 20 gig disks; each OS will probably take no more than ten gigs for minimal installs, two OSes per machine isn't terrible. (Incidentally, look around for a group like FreeGeek in your area -- larger hard drives ought to be cheap for small sizes like 120-500 gigs.)
That said, virtualization might be just what you need, if you have a handful of pretty powerful machines.
I think between one and two gigabytes of host memory for every guest VM that you want to run would be very useful. At least in my experience, an Ubuntu image I gave 1024 megabytes to ran very quickly, but I didn't press it very far. Running Firefox or OpenOffice inside the VM would probably dictate more memory very quickly. Chrome seemed snappy.
So, if you've got 12 gigabytes of RAM, you might be able to get between four and twenty virtual machines hosted on the machine simultaneously, depending upon what your guests are doing.
As for disk space, if you use QEMU's -snapshot option, you ought to be able to save disk space. Each user could boot the same underlying disk image, but their own modifications would go into the 'snapshot' file. (I have no experience trying to do long-term system maintenance with this option, so it could be that all twenty of your users need to store service pack 2 contents when they upgrade in the future; I'd be scared of trying to modify the shared disk image once you've got snapshots of it running. Perhaps having everyone store 'personal documents' and the like in CIFS shares would make a ton of sense.)
The biggest hurdle will probably be Mac; because the Apple terms of service forbid running OS X on non-Apple hardware, you'll have to have some Apple machines around to run VirtualBox.
Lately I have been thinking about investing in a worthy USB pen drive (something along the lines of this), and install Operating Systems on Virtual Machines and start developing on them.
What I have in mind is that I want to be able to carry my development boxes, being a Windows Distribution for .Net development and a Linux Distribution for stuff like RoR, Perl and whatnot, so that I would be able to carry them around where need be...be it work, school, different computers at home etc...
I am thinking of doing this also for backup purposes...ie to backup my almost-single VM file to an external hd, instead of doing routinely updates to my normal Windows Box. I am also thinking about maybe even committing the VM boxes under Source Control (is that even feasible?)
So, am I on the right track with this ? Do you suggest that I try to implement this out?
How feasible is it to have your development box on Virtual Machine that runs from a USB Pen-Drive ?
I absolutely agree with where you are heading. I wish to do this myself.
But if you don't already know, it's not just about drive size, believe it or not USB Flash drives can be much slower than your spinning disk drives!
This can be a big problem if you plan to actually run the VMs directly from the USB drive!
I've tried running a 4GB Windows XP VM on a 32GB Corsair Survivor and the VM was virtually unusuable! Also copying my 4GB VM off and back onto the drive was also quite slow - about 10 minutes to copy it onto the drive.
If you have an esata port I'd highly recommend looking at high-speed ESata options like this Kanguru 32GB ESata/USB Flash drive OR this 32GB one by OCZ.
The read and write speeds of these drives are much higher over ESata than other USB drives. And you can still use them as USB if you don't have an ESata port. Though if you don't have an ESata port you can buy PCI to ESata cards online and even ESata ExpressCards for your laptop.
EDIT: A side note, you'll find the USB flash drives use FAT instead of NTFS. You don't want to use NTFS because it makes a lot more reads & writes on the disk and your drive will only have a limited number of reads & writes before it dies. But by using FAT you'll be limited to max 2GB file size which might be a problem with your VM. If this is the case, you can split your VM disks into 2GB chunks. Also make sure you backup your VM daily incase your drive does reach it's maximum number of writes. :)
This article on USB thumbdrives states,
Never run disk-intensive applications
directly against files stored on the
thumb drive.
USB thumbdrives utilize flash memory and these have a maximum number of writes before going bad and corruption occurs. The author of the previously linked article found it to be in the range of 10,000 - 100,000 writes but if you are using a disk intensive application this could be an issue.
So if you do this, have an aggressive backup policy to backup your work. Similarly, if when you run your development suite, if it could write to the local hard drive as a temporary workspace this would be ideal.
Hopefully you are talking about interpreted language projects. I couldn't imagine compiling a C/C++ of any size on a VM, let alone a VM running off of a USB drive.
I do it quite frequently with Xen, but also include a bare metal bootable kernel on the drive. This is particularly useful when working on something from which a live CD will be based.
The bad side is the bloat on the VM image to keep it bootable across many machines .. so where you would normally build a very lean and mean paravirtualized kernel only .. you have to also include one that has everything including the kitchen sink (up to what you want, i.e. do you need Audio, or token ring, etc?)
I usually carry two sticks, one has Xen + a patched Linux 2.6.26, the other has my various guest images which are ready to boot either way. A debootstrapped copy of Debian or Ubuntu makes a great starting point to create the former.
If nothing else, its fun to tinker with. Sorry to be a bit GNU/Linux centric, but that's what I use exclusively :) I started messing around with this when I had to find an odd path to upgrading my distro, which was two years behind the current one. So, I strapped a guest, installed what I wanted and pointed GRUB at the new LV for my root file system. Inside, I just mounted my old /home LV and away I went.
Check out MojoPac:
http://www.mojopac.com/
Hard-core gamers use it to take world of warcraft with them on the go -- it should work fine for your development needs, at least on Windows. Use cygwin with it for your unix-dev needs.
I used to do this, and found that compiling was so deathly slow, it wasn't worth it.
Keep in mind that USB flash drives are extremely slow (maybe 10 to 100 times slower) compared to hard drives at random write performance (writing lots of small files to a partition which already has lots of files).
A typical build process using GNU tools will create lots of small files - a simple configure script creates thousands of small files and deletes them again just to test the environment before you even start compiling. You could be waiting a long time.