FreeBSD Host ZFS on Root Running VirtualBox with Windows Server 2003 Guests Very Slow HD Speeds
- You should update to 8.3 or 9.0, there are a lot of fixes in there.
- You should update VirtualBox. You need to update ports before doing this.
- Good way to setup disks would be:
- moving them to zvols, zvols can be transferred to VirtualBox by VBoxManage internalcommands createrawvmdk, this will makes it use less metadata and limits sectors to 8k (HINT: as your sectors default max to 512K almost each byte written will result in writing 512K block);
- all data on the virtual disk is already governed by virtualized system FS so you can finetune zfs vdev:
- sync=disabled, this will turn off logging on the disk, gives disk ability to not wait for long-running writes;
- logbias=throughput, when log is enabled new pages for data would be aquired from zpool, not from intent log, ditches double write; also data is written immediately;
- compression=on, in most environments this speeds up reading/writing;
- Don't use SCSI, SATA is a better way of using disk. After updating VirtualBox set hostiocache on controller.