| 1 | | I've found a usable workaround to be switching my disks in VirtualBox to IDE. The virtual IDE can still time out, but IDE's multisector read and write mode max at like 16 sectors (8KB), or maybe 256 sectors (128KB), versus SATA allowing for 64MB or more via larger transfers and native command queueing. In days of yore, SATA gave a massive speed increase in VMs compared to IDE (the 8KB transfers plus mucking about with I/O ports meant a lot of virtualization overhead); with VT-X flipped on the difference is fairly low. If my physical disk I/O is nice, the IDE runs nice; if the disk I/O is slow, the VMs simply run through their read and write queues pretty slowly, rather than spitting out large 64MB requests then timing out. |
| | 1 | I've found a usable workaround to be switching my disks in VirtualBox to IDE. The virtual IDE "can" still time out, but IDE's multisector read and write mode max at like 16 sectors (8KB), or maybe 256 sectors (128KB), versus SATA allowing for 64MB or more via larger transfers and native command queueing; that's 1/512th the data in that queue. In days of yore, SATA gave a massive speed increase in VMs compared to IDE (the 8KB transfers plus mucking about with I/O ports meant a lot of virtualization overhead); with VT-X flipped on the difference is low enough; I haven't run some synthetic disk I/O benchmark but in real use I can't tell the difference in terms of speed or CPU usage. If my physical disk I/O is nice, the IDE runs nice; if the disk I/O is slow, the VMs simply run through their read and write queues pretty slowly, rather than spitting out large 64MB requests then timing out. |
