The case against LVM

[Mikkel L. Ellertson]

Timothy Murphy wrote:
> Rick Stevens wrote:
> 
>> Well, the "x" in your example can take the RE form "[a-z]+".  For
>> example, we have some storage arrays with, oh, 130 LUNs on them.  They
>> appear as /dev/sda[1-15] through /dev/sdiv[1-15]
> 
> But you won't get this with the standard Fedora installation,
> which I assume is what people are talking about.
> You will be told you have disks /dev/sda and /dev/sdb, or whatever,
> and asked how you want to partition them.
> 
> You are saying, in effect, that you can make Fedora think
> one of your disks is in fact several different disks.
> That may be true, but not with the standard Fedora installation.
> 
> Incidentally, what do you mean by a "storage array"?
> The discussion was about partitioning a single disk, IIRC.
> 
With SCSI, there is a way to have more then one physical drive that
responds to one SCSI address. You can have 16 LUNs on one SCSI
address. Each LUN can be a physical drive, or part of a drive,
depending on the LUN controller used. I believe the "storage array"
he is talking about is several drives attached to a LUN controller.
This was more common when drives were smaller, but is still useful
when you need large/fast storage. The system does not need to know
how the storage array is set up - all it needs to know is that it
needs to send the SCSI command to something like device 4, LUN 2,
and the LUN controller does the rest. Setting up the LUN controller
in the first place may be complicated, but access the attached
devices is not. Oh yes - the "storage array" is normally an external
box with its own power supply, cooling, etc. You can hook a large
number of drives to a single SCSI controller this way.

Mikkel
-- 

  Do not meddle in the affairs of dragons,
for thou art crunchy and taste good with Ketchup!

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