Niall,
Niall Power wrote:
> More comments/questions after having spent more timing examining the
> disk layout modelling:)
>
> 4.1.1:
> The data model assumes that only one VTOC (DiskSlices_t) can exist
> on disk. On X86, the DiskSlice_t is associated with a parition. Will the
> assumption on X86 that only one partition can contain a VTOC hold true
> in the future? Will ZFS make this irrelevant?
>
> --------------------------------------------------------------------------------------
> typedef struct {
> char *diskName; /* Disk Name
> for look up */
> PartitionInfo_t pinfo[FD_NUMPART]; /* fdisk
> partitions */
> } DiskParts_t;
>
> How is the pinfo[FD_NUMPART] array ordered? Is it ordered by partition ID or
> by
> physical partition order on the disk?
>
The partitions are listed based on the partition id. Partition numbers
are set based on the order of creation.
>
> --------------------------------------------------------------------------------------
> typedef struct {
> int partitionId; /* fdisk id (1-4) */
> int partitionOrder; /* Order in the disk */
> int partitionType; /* Solaris/linux swap/X86boot */
> om_content_type_t contentType; /* Solaris/Linux */
> long partitionSize; /* Size in GB */
> boolean_t active; /* Is the partition active */
>
> } PartitionInfo_t;
>
> There is no indication of of where the partition offset starts or ends on the
> disk. It forces us to
> assume that partition at order 0 begins at offset 0 and, partition at order 1
> begins immediately
> after where partition at order 0 ends and so on. This seems like a dangerous
> assumption.
> We discussed this briefly during the work week and about how the GUI would
> handle it. I believe
> we said the GUI, due to it's design would not support it (it doesn't convey
> start and end points of
> partitions to the user) and so it would issue a warning and force a
> destructive repartitioning of the disk.
> But from the data modelling perspective, partition start and end offsets seem
> like important data to capture.
>
I was thinking of not exposing disk information like starting cylinder
and offset. I was hoping that we can get away by providing the
partitionOrder information. It looks like we need to provide starting
cylinder and offset. I will add this information and remove
partitionOrder from the PartitionInfo_t.
- Sundar
> Thanks,
> Niall.
> --
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