﻿id,summary,reporter,owner,description,type,status,component,version,resolution,keywords,cc,guest,host
19717,Storage IO Erros With virtio-scsi Controller When Host I/O Cache is Enabled => fixed in SVN/next 7.0.x and 6.1.x maintenance,Miky.Ne,,"On Ubuntu Server 20.04 guest in Virtualbox 6.1.2 on a Win10 (2004) host:
I've selected the virtio-scsi controller and enabled the host I/O cache option to maximize performance. With this configuration, I see multiple I/O related errors in the guest's shell and dmesg log (""Buffer I/O error on device sda2, logical block xxxxxxx"", ""I/O error, dev sda, sector yyyyyy op 0x0:(READ) flags 0x80700 phys_seg 20 prio class 0"", and many others). On the host's log I see multiple messages like ""SCSI#0: Read at offset xxxxxxxxx (4096 bytes left) returned rc=VERR_NOT_IMPLEMENTED"".

All above errors disappear when host I/O cache is disabled.
This seems to have started with Virtualbox 6.1.2. When downgrading to Virtuabox 6.1.0 There are no problems when cache is enabled.

Attached are 2 logs for the same machine (created and running on Virtualbox 6.1.2), one with the cache enabled and the other disabled.

Any help will be much appreciated.

I have reported the problem in the Virtualbox forums:[https://forums.virtualbox.org/viewtopic.php?f=3&t=98962], no responses. ",defect,closed,virtual disk,VirtualBox 6.1.2,fixed,I/O cache VERR_NOT_IMPLEMENTED,,Linux,Windows
