On Oct 23, 2017, at 8:57 PM, Daniel Boyd <danieljb...@icloud.com> wrote: > > Thanks for the helpful response. > > FYI, I did some more research and discovered that Hyper-V doesn’t support > booting from virtual SCSI drives, so that solves that. > > I have another vm running on my laptop under KVM that runs substantially > faster than the hyper-v vm. My laptop is far below the hyper-v server in > most respects performance-wise, but it does have an SSD. I’d be curious to > find out how much of that is raw disk IO performance and how much is KVM vs > Hyper-V and openbsd’s respective drivers for each. > > I’ll give the softdeps suggestion a shot. > > Sent from my iPhone > >>> On Oct 23, 2017, at 7:25 PM, Nick Holland <n...@holland-consulting.net> >>> wrote: >>> >>> On 10/23/17 17:41, Daniel Boyd wrote: >>> Is there a recommended configuration for virtual disks in Hyper-V? I >>> have a virtual machine that I set up recently running 6.2 that has >>> *very* slow disk performance. It took well over an hour to untar >>> ports.tar.gz. The host server is a few years old, but it's running 3 >>> RAID-5 7200rpm drives, quad-core Xeon and 32 GB RAM... so not exactly a >>> slow machine. And this is the only Hyper-V VM it's hosting. >> >> actually...raid5 is slow on writes (write one block = read existing >> block. Read parity block. Write data, write parity. Hopefully, you >> have a write cache that's on and working), 7200rpm drives are slow by >> any standards these days. That's a heavy-lifting drive, not anything to >> mention in the same sentence as "not slow". >> >> (don't get me wrong, I got a lot of heavy-lifting drives. And I'm kinda >> slow. But I try to be realistic about it). >> >>> I've got the virtual disk configured as IDE / VHDX / Expanding (the >>> Hyper-V defaults). >> >> "expanding" means not preallocating the disk, I'm guessing? Again, not >> a performance choice. Your file system fragments are going to be >> fragmented. >> >>> The controller can be IDE or SCSI. The disk format >>> can be VHD or VHDX. And the disk can be configured as fixed or >>> expanding. I'm going to try converting the disk to fixed and >>> defragging my NTFS. >>> >>> Any thoughts on IDE vs SCSI and VHD vs VHDX? >> >> Neat thing: OpenBSD doesn't care much. You can change it at the >> hypervisor level, reboot, and see for yourself how it works. This isn't >> Windows or Linux which will have a cow if you change the disk type or >> controller type after load. (before DUIDs, you might have to change your >> /etc/fstab, but as long as you are using DUIDs, you should be in good >> shape there). >> >> But ... for unpacking ports, make sure that file system is mounted (at >> the OpenBSD level) with softdeps. Yes, it's really a huge difference >> for lots of tiny files, which is exactly what the ports tree is. This >> will matter more than hypervisor knobs, I suspect. >> >> Nick. >> >
Also, out of curiosity, why is softdep not enabled by default? Assume there must be some downside to having it on?
