[ILUG] dying hard disc - upgrade questions?

[Rick Moen]

Quoting Brian Foster (blf at utvinternet.ie):

> QUESTION:  how can I work out if my controller et.al.  is ATA-1,
> ATA-2, ATAPI, or something else?

1. Try "dmesg | more" , but
2. Don't spend too much time worrying about it.  It's not really important.

> I don't see an issue with WT (write-through) cache, but WB
> (write-back) caches can cause data integrity problems (e.g., on power
> failure), albeit if the driver/ATA/IDE/cache(/BIOS?) supports flush
> and barrier operations, then it is perhaps Ok.
> 
> QUESTION:  should I steer clear of the drives with ???cache???, or are
> they generally Ok?

No.  All ATA drives include disk-cache RAM.  It's normal.

And yes, you _should_ worry about problems consequent to (e.g.)
power loss.  Have current backups.  Plan for recovery.

> on the matter of physically installing the new drive, I am aware it
> will need to be jumpered appropriately, albeit I'm not quite sure what
> ???appropriate??? means here .... presumably as the master(?) if it is
> the only drive; if the old 40Gb is still present (which I thus assume
> is the master), as the slave(?) --- but then can I boot _exclusively_
> from the slave without the master being involved (or even present?)?

Your flexibility in booting is determined mostly by the motherboard
BIOS.  Experiment and find out.  (Experiment with what you can do in the
BIOS setup and your bootloader, that is.  Your hard drive jumpers should
be set appropriately for each drive's position on the chain.  I would
discourage use of "cable select".  It's been known to cause problems.)

> I've read conflicting (albeit not contradictory) explanations of
> extended partitions.  the combined ghist seems to be they form a
> chain.  the contents of each extended partition in the chain is a
> partition table plus physically adjacent space, which is divided into
> the logical partitions as defined/referenced by that extended
> partition's partition table.
> 
> the conflicts are whether or not you can (or should) have more than
> one logical per extended; and whether or not the pointer to the next
> extended in the chain must be the last entry in the (prior) partition
> table.

What you may be thinking of is that a _particular_ extended partition's
table may have multiple four-entry extents, each linking to the next.  

> QUESTION:  what constitutes ???best practice??? when using extended
> partitions? 

I can't imagine a need for more than one extended partition per physical
drive.  Create within that partition as many logical drives (the actual
data-bearing structures) as you deem necessary.

I vaguely recall that some things work properly only from a primary
partition, e.g., the unnamed Microsoft primary bootloader (the one you 
write to your first HD when you type "FDISK /MBR" at the DOS prompt)
will boot only from the first primary partition bearing the bootable
(aka "active") flag.

You may want to try to order your filesystems ("partition") in such a
way as to (you hope) minimise disk seeking.  It's something of a
debatable art form, so try what you think makes sense, and see how it
works out.

-- 
Cheers,   "Why is the alphabet in that order?  Is it because of that song?"
Rick Moen                                              -- Steven Wright
rick at linuxmafia.com