Re: The case against LVM

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Robert P. J. Day wrote:

not to harp on this, but can someone confirm that, with standard hard
disks and partitioning, the limits are:

1) 4 primary partitions
2) only one of which can be extended
3) that extended partition can hold up to 12 logical partitions (this
limit is different from IDE to SCSI, as i recall)

This is not quite correct.

For a standard partition table (PT) there are up to four entries.
Each entry may be either primary or extended, but not more than
one entry may be extended.
Each primary partition may contain up to one logical volume.
If an extended partition exists, then any number of logical
volumes may be created, space permitting.

SCSI is a physical interface and a physical protocol. What you
do with it depends on the driver installed.

IDE is not a physical interface, it is a disc drive description.
The physical interface is properly called ATA. What you do with
it depends on how you want to use it.

There are more than one partitioning scheme. Any of them can
be used with either SCSI or ATA. Whether software to allow this
exists, I don't know. Partitioning schemes are conventions for
partitioning drives, they are part of the format. They are not
part of the physical access method. So SCSI and ATA, being physical
access methods, are independent of format.

That's not to say that often by convention only certain
formats are used with certain physical access methods.

  in any event, it's simply not true that you can have an unbounded
number of logical partitions on a single drive, unless something's
changed drastically lately.

Space permitting, one may have potentially any number of logical
volumes.

The format levels are

structured file/database (application specific)
file system/volume format (file system specific)
partition format
physical format
physical I/F

The access levels are

structured file/database (application specific, records, fields, etc.)
file level (file name)
logical level (partition + logical sector within partition)
logical/physical level (logical sector on disc)
physical level (C/H/S)

Mike
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