BIOS call int13h cannot access more than 4 HDDs on the SATA or SCSI controller.

[Yano]

When I set up 6 HDDs on SATA controller, BIOS in VirtualBox does not recognize last 2 HDDs. If the last 2 HDDs are connected to SCSI controller, i.e. 4 HDDs on SATA and 2 HDDs on SCSI, all the 6 HDDs can be accessed via int13h.

Similarly, more than 4 HDDs on SCSI and SAS controller cannot be accessed by int13.

This causes boot failure problem of linux in software RAID5 partition with 6 HDDs.

The "User Manual" says VirtualBox supports 4 HDDs to IDE, 30 HDDs to SATA, 15 HDDs to SCSI and 8 HDDs to SAS controller. Since real PC BIOS can access all the HDDs connected to SCSI controller as usual, this is a bug of VirtualBox BIOS, I believe.

This problem is also in version 4.2.2 and 4.2.0, and maybe older version.

[Klaus Espenlaub]

This is actually intentional behavior - there is limited space in the EBDA, which means that the BIOS can only support a limited number of drives. At the moment it supports 4 IDE, 4 SATA and 4 SCSI drives at boot time.

In any case - who needs RAID-5 to boot a VM?

[Yano]

Thank you for replying.

who needs RAID-5 to boot a VM?

I'm using VM to practice experimental operations on linux server. So I hope management of RAID disks can be done on VM.

Recent GRUB2 has supported booting from RAID5 partition. So I have tried to install linux on RAID5 using VirtualBox, but it failed because of this problem.

[lrosenman]

I also ran into this "issue" with booting a FreeBSD_64 ZFS RaidZ1 pool with 6 disks. I'd like to see the BIOS updated to support at least 8 disks on each type of controller.