On 5/1/2011 10:54 PM, John wrote:
-----Original Message-----
From: Ted Mittelstaedt<t...@mittelstaedt.us>
On 4/30/2011 7:28 PM, typo W wrote:
Hi, I'm brand new to virtualbox, so pardon me in case I made
stupid mistakes. I created a FreeBSD guest out of the regular
virtualbox port (3.2.12) on FreeBSD 8.2, then timed the copying
of a 320MB binary file to another file, which took 4 seconds, ie,
80MB/s. On an identical hardware I created a CentOS guest out of
KVM running on CentOS, and the same operation only takes 1
second. On both hosts, the copy takes 1 second. That is,
virtualbox slowed the copying to 1/4 speed on my guest FreeBSD.
Both hosts are Dell R710, with 6 x 600GB 15K SAS drives forming
a RAID6 with R700 controller with 512MB cache.
Try some file copies at the base OS and let us know the results.
I would guess that the FreeBSD hardware RAID device driver for the
R700 controller isn't using the hardware write caching of the
controller. When the FreeBSD host OS got the file write call from
the virtual box it should have issued the write to the disk
controller and then returned immediately since the write should
have gone into the hardware cache of the controller.
you can also try playing with the sync/async options in the host
OS. See the mount command for details. it is kind of pointless to
do sync writes on a caching hardware controller because the entire
point of sync writes is to keep the data from being scrambled in a
crash or if there is sudden power loss - but the cache in the
hardware array card is more than capable of screwing the
filesystem if that happens.
Ted
On both the FreeBSD host and the CentOS host, the copying only takes
1 second, as tested before. Actually, the classic "dd" test is
slightly faster on the FreeBSD host than on the CentOS host.
The storage I chose for the virtualbox guest is a SAS controller. I
found by default it did not enable "Use Host I/O Cache". I just
enabled that and rebooted the guest. Now the copying on the guest
takes 3 seconds. Still, that's clearly slower than 1 second.
Any other things I can try? I love FreeBSD and hope we can sort this
out.
did you try mounting the filesystem that the virtualbox is writing to,
async? what is the contents of the freebsd host /etc/fstab?
Ted
Thanks, John
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