12 Troubleshooting 12.6.8 PAX/grsec kernels Linux kernels including the grsec patch (see http://www.grsecurity.net/) and derivates have to disable PAX_MPROTECT for the VBox binaries to be able to start a VM. The reason is that VBox has to create executable code on anonymous memory. 12.6.9 Linux kernel vmalloc pool exhausted When running a large number of VMs with a lot of RAM on a Linux system (say 20 VMs with 1GB of RAM each), additional VMs might fail to start with a kernel error saying that the vmalloc pool is exhausted and should be extended. The error message also tells you to specify vmalloc=256MB in your kernel parameter list. If adding this parameter to your GRUB or LILO configuration makes the kernel fail to boot (with a weird error message such as “failed to mount the root partition”), then you have probably run into a memory conflict of your kernel and initial RAM disk. This can be solved by adding the following parameter to your GRUB configuration: uppermem 524288 12.7 Solaris hosts 12.7.1 Cannot start VM, not enough contiguous memory The ZFS file system is known to use all available RAM as cache if the default system settings are not changed. This may lead to a heavy fragmentation of the host memory preventing VirtualBox VMs from being started. We recommend to limit the ZFS cache by adding a line set zfs:zfs_arc_max = xxxx to /etc/system where xxxx bytes is the amount of memory usable for the ZFS cache. 12.7.2 VM aborts with out of memory errors on Solaris 10 hosts 32-bit Solaris 10 hosts (bug 1225025) require swap space equal to, or greater than the host’s physical memory size. For example, 8 GB physical memory would require at least 8 GB swap. This can be configured during a Solaris 10 install by choosing a ’custom install’ and changing the default partitions. Note: This restriction applies only to 32-bit Solaris hosts, 64-bit hosts are not affected! For existing Solaris 10 installs, an additional swap image needs to be mounted and used as swap. Hence if you have 1 GB swap and 8 GB of physical memory, you require to add 7 GB more swap. This can be done as follows: For ZFS (as root user): zfs create -V 8gb /_ZFS volume_/swap swap -a /dev/zvol/dsk/_ZFS volume_/swap To mount if after reboot, add the following line to /etc/vfstab: /dev/zvol/dsk/_ZFS volume_/swap - - swap - no - Alternatively, you could grow the existing swap using: zfs set volsize=8G rpool/swap 177