A recent weblog of Alexandre Chartre's discusses LDoms Virtual Disks, beginning with the examination of the components of the virtual disk, which are the virtual disk itself and the virtual disk backend. The first is a domain guest and the second a locale where data is stored and where virtual I/Os end up.

He goes on to consider the manner in which the virtual disk backend -- in its several forms: physical disk; physical disk slice; a file; or a volume from a volume management framework -- can be exported from a domain, which includes as a full disk or a single slice disk. He points out that a backend exported to a domain as a single slice disk will appear in that domain as a disk with a single partition but will not be visible with the format command; in addition, its partition table cannot be changed, he adds.

Chartre further notes that a single slice disk will not be visible from the Solaris installer and cannot be selected as a disk device on which the Solaris Operating System (Solaris OS) can be installed.

In his discussion of both the physical disk and the physical disk slice, Chartre supports the detail with code samples.

The author also discusses exporting a file as a full disk, observing that virtual disk drivers (vds and vdc) forward I/Os from the virtual disk and manage the partitioning of the virtual disk, eventually becoming a file that is a disk image storing data of all slices of the virtual disk.

He next shows how the system writes a default disk label into a file exported as a virtual disk without partitioning information stored in the file itself.

Finally, before answering several FAQs on the subject, Chartre considers the export of a volume as a single slice disk. Visit The HyperTrap for his complete entry. [...read more...]

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