Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 7 years ago.
Improve this question
I am trying to run my Chef/Kitchen tests that use Vagrant/Virtualbox on an ESXi VMWare cluster guest to test cookbook integration. I will likely move to a VMWare version for Kitchen/Vagrant and remove the Virtualbox portion at some point but would like to see this work first.
I have the virtualization support turned on in the VM so it does function, but it is excruciatingly slow. Where the full converge on my desktop is done in under 4 minutes, it takes nearly 40 minutes in the VM. Checking perfomance on the VMWare VM and it seems acceptable, but the VirtualBox VM inside it has very high Hardware Interrupt service. All other metrics seem to be about average. Where HI rarely gets about 1-2 under normal systems it is steady >30 even while idle in the Virtualbox guest and often above 50.
Any ideas on what to look for or magic settings I may have missed?
After reading the very helpful article linked to by itfdev at https://egustafson.github.io/esxi-nested-virtualbox.html I have found that what I want to do will likely always be slow due to the quote below:
Disk Performance
During my initial experimentation with nested VM’s I observed a clear decrease in performance of the nested VM. My initial experimentation mostly only went as far as installing the OS on the nested VM. Installing an OS is generally a disk intensive activity.
Disk virtualization is more expensive than most. Nesting virtualized disks will accumulate "virtualization debt" quicker than other virtualized components. The short, but rambling explanation goes something like this:
In my inner VM I write a block to "disk". This traverses the inner OS’s file system code and is mapped to a sector on the inner VM’s virtual block device. Writing is the passed to the outer VM, traverses the file system code, and is mapped to the outer VM’s virtual block device. Finally, the block is passed to the host, (physical), file system, mapped through to a sector, and finally
placed on the actual physical device. — If your head is spinning now, it
should be. That’s three times the block is passed through file system code on it’s eventual path to a physical write.
This problem is understood in the virtualization community, and there are methods for avoiding differing degrees of the penalty based on the requirements of an installation. I will not cover these here. My point: if your nested VM’s strike you as slow, this may be a significant part of the why.
VirtualBox, running in the virtual environment, can only use "software" virtualization. It's slow, of course. It should consume a lot of processor time. ESXi in a host system use hardware acceleration (VT-x or similar), and it performance close to real host performance. You should not install VM on VM.
Related
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 10 months ago.
Improve this question
My mac is sending me the frequent alert of low disk space. When I am checking the system storage then it's showing 170+gb is occupied by the system. I am not sure where is my space is getting used?
I tried a few cleaner tools also but couldn't get help much.
Please help to resolve it?
After doing research over various forums of mac's and StackExchange I figured out that it's mostly because of the following reasons.
Log files (Might be crash log files/docker files)
Your email messages stored in outlook (in my case it was almost ~20 GB)
Logs related to cores when a system restarts (~ 10 GB)
Docker Images (This had ~70 GB in my case).
Your nonsystem documents/downloads/itunes
So the question is how to find what all things are unnecessary and safe to delete? These system files are not visible directly.
I tried using a few tools like cleanmymac etc but all were paid so I couldn't get help much there.
To clean up your non-system unnecessary files, you can directly take the help of the storage management tool of mac. You just have to click on optimize storage and it will show all the non-system files.
To cleanup unnecessary system files, use below command
sudo find -x / -type f -size +10G
This command will give you all the files occupying more than 10 GB. You can analyze the files and delete them as necessary.
The highlighted cores are nothing but the state files of your mac to reboot from last state when your mac restarts so it's safe to delete.
Next step is to delete a hidden tmp folder
It will show the size as 0 bytes because your user won't have permission to read it. But will be occupying a hell amount of space. So delete it by giving root permission.
Now, Look if there are any docker images present in your system. Clean them all (Docker.raw).
Using all these steps I was able to clean almost 100+ GB.
Recently found that this issue was caused by a memory leak in one of the Java applications I was running. I had to start the Activity Monitor, searching for Java processes and Force Quit them. Rinse and repeat every time my space runs out. Also fix your code where you can to get rid of memory leaks.
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 9 years ago.
Improve this question
Why do some software require system restart in windows ?
Meanwhile , I have never encountered such situation in Linux based Distros.
It is innate to the way Windows was designed. Loading an executable doesn't load the file into RAM. Windows creates a memory-mapped file for the executable instead. Chunks of the program get loaded into RAM on demand only as needed. A page fault copies 4096 bytes from the file. The RAM pages themselves are not backed by the paging file. If RAM is needed for other processes then Windows simply unmaps the page and throws away the bytes it contains. If the process again lands on the page then a page fault reloads RAM from the file. Very efficient, this mattered a great deal when you need to run a 32-bit operating system and many processes in only 16 megabytes of RAM. Still efficient today, but not as critical as it once was.
One side-effect of the memory-mapped file is that it puts a write lock on the file. Necessary to prevent another processes from altering the executable. That would be disastrous, RAM could contain a mix of old and new bytes in the file. That's guaranteed to cause the program to malfunction.
Of course that makes the life harder for programs that intentionally want to change the executable. Including the malicious variety btw. So having to stop the processes that have the file loaded is required, it releases the write lock. An update delivered through Windows Update tends to update executables that cannot easily be unloaded since they are part of the operating system. Which is the reason they tend to require a reboot, the file is updated as part of the boot sequence when the machine restarts.
One way to bypass the lock is to rename the file. The lock only protects the file data, not the directory entry. You can then create a new directory entry with the same name as the old one. And the next time the process gets started, it will use the new entry. One minor complication is that you have to eventually delete the renamed file.
One thing I can think of is that some software requires services to be running for it to run properly. The restart likely adds these services to the ones that automatically run when you start the computer so that the program can run smoothly.
Hypervisors and Memory Management
I have been using virtual machines for years and never really had any issues. I have primarily used VMWare's free single ESXi host and had nothing but success. Because I have never had any issues I have never delved in much deeper. I have however always been very wary of loading the system up and get a lot of spare resources handy.
I have recently purchased a new server and we have decided to give Hyper-V a try and see how that goes. We have a fairly small team but utilise lots of servers for testing etc.
My question relates to memory and how much I need to leave free or available for the host machine to run appropriately.
Setup:Dell Server 24 Cores: 48GB Ram
When I run taskmgr in the windows host instance I see the following:
Physical Memory: 49139
Cached: 14933
Available: 17743
Free: 2982
What exactly do these figures mean? What is the difference between free and available?
My server uses hardly any CPU resources ever and has 10 Production servers running on it without a single user complaint ever about speed of the services.
Am I able to run up another server with 2GB ram effectivly leaving 982MB free? or am I starting to push my requirements a little?
Thanks for the help.
You shouldn’t use the host partition for anything other than Hyper-V (although you can run security and infrastructure software such as management agents, backup agents and firewalls). Therefore, that 2GB recommendation assumes you aren’t going to run any extra applications or server roles in the parent partition.
Hyper-V doesn’t let you allocate memory directly to the host partition. It essentially uses whatever memory is left over. Therefore, you have to remember to leave 2GB of your host server’s memory not allocated so it’s available for the parent partition.
Source
Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.
This question does not appear to be about a specific programming problem, a software algorithm, or software tools primarily used by programmers. If you believe the question would be on-topic on another Stack Exchange site, you can leave a comment to explain where the question may be able to be answered.
Closed 5 years ago.
Improve this question
Problem:
I keep getting Hash: Element not found errors.
Technical Details:
uTorrent 3.2.3 (latest as of this writing)
Running about 30 Torrents (all downloading)
Win 7 64 bit
Dell N5050 :sigh:
Symptoms:
Force recheck is disabled (sometimes)
When I resume the torrent, as it halts when this happens, it proceeds smoothly until the next Hash: Element not found error
It doesn't happen at a particular %age
Solutions Attempted:
Searched online a lot to find a few below
Re-download elsewhere. Set download folder and change it and re-download the torrent. NO! DOESN'T WORK! and its FRUSTRATING that I'd to DELETE my 90% downloaded torrent!!
Good 'ol thump. Swear at the screen making heavy fist thumps and hand gestures. Surprisingly, this doesn't work!
Force recheck. Doesn't help and sometimes not available.
Disk I/O errors. Came across an article which said this might due to Disk I/O errors.
Realized I was using a DELL laptop
Realized HDD had failed on a previous DELL
Tried Solution #2 again. Same results.
Seemed like the most likely explanation to the problem, hence read articles about HDD checking and downloaded a few suggested softwares to check HDD Health
Interestingly, the HDD was a OK
None of these worked!
I got this error when my hard drive ran out of disk space, so I think it is related to some file / disk access issue, depending on where you are writing to
I was trying to download some large files to a network drive (Windows XP to Samba) and I was getting the same Element Not Found error.
In my case, enabling the disk cache has solved the issue. I had to uncheck the Disable Windows caching of disk writes and Disable Windows caching of disk reads options under uTorrent Options -> Preferences -> Advanced -> Disk Cache (this way enabling the cache).
Source: http://forum.utorrent.com/topic/34159-error-element-not-found/page-2#entry251137
I really think this question belongs to SuperUser though.
The working solution turned out to be pretty simple.
Check your Anti-Virus!
My antivirus was quietly quarantining a few suspected files.
Added those files to the exclusion list.
All is well again.
Closed. This question is off-topic. It is not currently accepting answers.
Want to improve this question? Update the question so it's on-topic for Stack Overflow.
Closed 11 years ago.
Improve this question
I know this isn't strictly speaking a programming question but something I always hear from pseudo-techies is that having a lot of entries in your registry slows down your Windows-based PC. I think this notion comes from people who are trying to troubleshoot their PC and why it's running so slow and they open up the registry at some point and see leftover entries from programs they uninstalled ages ago.
But is there any truth to this idea? I would not think so since the registry is essentially just a database and drilling down to an entry wouldn't take significantly longer on a larger registry. But does it?
EDIT: To be clear, I'm not looking for advice on how to make a PC run faster, or asking why my PC in particular is slow (it's not), I'm just curious if people who say "bigger registry means slower PC" are accurate or not.
I think its a symptom, not a cause, as fever is a symptom of an infection.
When you install windows updates, at least in xp and up, a folder called SXS is maintained for rolling them back. These rollback points are also stored in reg keys.
The size of the sxs(side by side) folder grows exponentially and definitely has been linked to why, when some people simple reinstall with sp3 instead of installing sp1 and rolling up to sp3 they get better performance, even with the same programs installed.
1) Start -> Run -> msconfig
2) Check the Startup tab
3) If you don't know what it is, uncheck
4) Reboot
Its not the registry, its the crap you have running in the background.
In short, not really.
In the old days when machines were slower the answer was yes; but having a modern processor rip through even a 60MB registry is not a problem.
Typically, the real reason a modern machine starts running slow is due to everything from malware to virus scanners: Mcafee, Norton's, etc are prime targets in my mind.
Also, the WinSXS folder tends to grow as service packs and applications are installed. This seems to have a negative impact on system performance. There are only two possible solutions in this scenario. First, if possible, reinstall the OS with the latest service pack already slipstreamed into the install. Second, if that isn't possible AND you are running Vista with SP1, you can run the vsp1cln.exe tool (see technet) which will clean up a lot of the older versions of components. Note that this tool can only be executed once and it does not allow you to roll back.
any problems occur on the registry could also make your computer much slower.the fix registry problems you need to install a registry cleaner as this will fix the errors and make your pc back to its normal state.