On 06/02/2015 08:54 PM, David Weber wrote: > Hello, > > I'm currently evaluating to switch our virtualization servers to a newer OS. > This includes a switch from qemu 1.7 to 2.2 or 2.3. > Our system heavily relies on big sparse images and drive_mirror. While > testing, I experienced some problems with that combination. > The strange thing is, that everything works flawlessly on my workstation but > fails on my servers. > > Testcase: > # qemu-img create test 500G > # time qemu-img map test > > Systems: > O3-3: Kubuntu 15.04 Workstation with stock-kernel 3.19.0-18-generic and stock > qemu 2.2.0 > Dinah: Ubuntu Server 15.04 with stock-kernel 3.19.0-18-generic and stock qemu > 2.2.0 > > Result on O3-3: > root@o3-3:~# qemu-img create test 500G > Formatting 'test', fmt=raw size=536870912000 > root@o3-3:~# time qemu-img map test > Offset Length Mapped to File > > real 0m0.049s > user 0m0.048s > sys 0m0.000s > > Result on dinah: > root@dinah:~# qemu-img create test 500G > Formatting 'test', fmt=raw size=536870912000 > root@dinah:~# time qemu-img map test > Offset Length Mapped to File > ^C > > real 0m41.862s > user 0m0.004s > sys 0m0.068s > (Stopped with ^C)
Do you use the same filesystem? Thanks Wen Congyang > > Strace on O3-3: > https://gist.github.com/anonymous/f221035e9176f7c71c74 > > Strace on dinah: > https://gist.github.com/anonymous/40b42888a65478c90b32 > > A git bisect between 1.7 and master revealed > 7c15903789953ead14a417882657d52dc0c19a24 "block/raw-posix: use seek_hole > ahead > of fiemap" as bad but this is not the real problem. > I also tried to switch from btrfs to ext4 but it didn't change anything. > > At this point, I was pretty sure that was just stupit and missing something > trivial. > I then startet a fedora 22 live system and I saw the same problem. It happens > on both the ramdisk and a ext4 filesystem. > > Any ideas on this? I'm pretty much stuck at this point. Please ask if you > need > more information. > > Cheers, > David > > >
