[GTALUG] MBR and GTP Drives

D. Hugh Redelmeier hugh at mimosa.com
Mon Oct 9 16:24:01 EDT 2017


| From: James Knott via talk <talk at gtalug.org>
| 
| On 10/07/2017 08:53 PM, Howard Gibson via talk wrote:

| > Best Buy offered me a newer Seagate at a slightly lower price but one 
| > is claimed explicity to support Linux, and it supports some older 
| > protocols.  When I told the people at the store I wanted MBR, not GTP, 
| > they just stared at me.
| 
| That's proof store clerks are not allowed to know what they're talking
| about.  What does a disk drive care about what OS is on it?  All it does
| is read/write data from specified locations on the disk.

The PC world is full of hardware and software of various levels of
conformance to various "standards".

As a consequence, when someone builds a new component, they often try
to trick old components into working.  These tricks can sometimes be
indistinguishable from bugs.

Here are some such HDD tricks that I remember:

- jumpers to have drives report smaller capacity to overcome OS or
  BIOS limitations

- ATA drives that will pretend to have any geometry (picked from some
  clues during booting, I think).  Of course they actually had no
  geometry

- "hybrid" drives (HDD with modest SSD cache) that "knew" OS disk
  access patterns and allocated SSD to match

- drives with 4k sectors that faked 512 sectors (to various extents)
  to allow old BIOSes to boot from them

- drives that claimed their on-disk cache was flushed before it was.

But I don't remember any disks that were not supported by Linux.


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