Comparing Filesystem Performance in Virtual Machines
mitchellh.com
Comparing Filesystem Performance in Virtual Machines
1–10 of 46 posts
Re: Comparing Filesystem Performance in Virtual Machines
#2just a note: Mitchell Hashimoto is the mastermind behind Vagrant and Packer.
Re: Comparing Filesystem Performance in Virtual Machines
#3How is it that native is slower then virtual i/o in his tests? I don't get it... if it's only reading some cached data, it's not a real test scenario, isn't it?
So i suppose, the host system caches the reads. Also, how could it possibly be true that native writes are slower then virtual writes?
Re: Comparing Filesystem Performance in Virtual Machines
#4How is it that native is slower then virtual i/o in his tests? I don't get it... if it's only reading some cached data, it's not a real test scenario, isn't it? So i suppose, the host system caches the reads. Also, how could it possibly be true that native writes are slower then virtual writes?
From the article:
It is interesting that sometimes the native filesystem within the virtual machine outperforms the native filesystem on the host machine. This test uses raw read system calls with zero user-space buffering. It is very likely that the hypervisors do buffering for reads from their virtual machines, so they’re seeing better performance from not context switching to the native kernel as much. This theory is further supported by looking at the raw result data for fread benchmarks. In those tests, the native filesystem beats the virtual filesystems every time.
Re: Comparing Filesystem Performance in Virtual Machines
#5Is it just me or do the graphs not match up to the text in several places? For example in the 64MB random file write graph (http://i.imgur.com/iGxn2H1.png) green is the vmware native according to the legend, which is clearly the highest bar graph across the board, yet he says "VirtualBox continues to outperform VMware on writes"
Re: Comparing Filesystem Performance in Virtual Machines
#6How is it that native is slower then virtual i/o in his tests? I don't get it... if it's only reading some cached data, it's not a real test scenario, isn't it? So i suppose, the host system caches the reads. Also, how could it possibly be true that native writes are slower then virtual writes?
It could be because native is running OS X but they're running Ubuntu inside the VM.
Re: Comparing Filesystem Performance in Virtual Machines
#7How is it that native is slower then virtual i/o in his tests? I don't get it... if it's only reading some cached data, it's not a real test scenario, isn't it? So i suppose, the host system caches the reads. Also, how could it possibly be true that native writes are slower then virtual writes?
On write, the VM probably reports that data is written to disk when it's written to an in-memory cache, then writes it to actual disk. So write is faster because the application is being lied to, not actual performance. That wouldn't explain the rads, though.
Re: Comparing Filesystem Performance in Virtual Machines
#8Is it just me or do the graphs not match up to the text in several places? For example in the 64MB random file write graph ( http://i.imgur.com/iGxn2H1.png ) green is the vmware native according to the legend, which is clearly the highest bar graph across the board, yet he says "VirtualBox continues to outperform VMware on writes"
He's probably talking about the Shared Folders performance.
Re: Comparing Filesystem Performance in Virtual Machines
#9Interesting and timely article! On an Ubuntu guest (Windows host), I install the Samba server and then use the native Windows CIFS client to connect to the Ubuntu host. This gives me the advantage of vm (virtualbox) native filesystem and letting me use my windows machine to open files on the guest
Perhaps this support can be added to some later version of vagrant
Re: Comparing Filesystem Performance in Virtual Machines
#103GB/s writes on a single SSD should raise more eyebrows. I dunno what was actually benchmarked, but there's a problem somewhere...