zfs discuss - May 2006 - Did Sol9 have a 1Tb limit on addressing IDE, does S10, would ZFS be impacted?

Hello All,


Attached is a conversation I''ve had with an old friend / colleague /
sysadmin (cc''ed) and it raises three questions for me.

I would like to ask the panel, from the context as described below:


	Did Sol9 have a 1Tb limit on addressing IDE

	Does S10?

	Would ZFS be impacted if using >1Tb IDE devices?


...along with any general constructive commentary/feedback on the
issue described...

Thanks,

	- alec


---- snip snip ----


him:

 >The terabyte drive is on the way.. I just hope OS writers can keep
 >up; it''s the underlying disk access layer that has problems.
 >Solaris uses a pseudo-SCSI interface for IDE, which runs out of CHS
 >at 1TB.  This is why our 4.2TB RAIDs had to be split into 5 virtual
 >drives.  I don''t know how the FC interface gets over that problem.

me:

 >so you are presenting your raid arrays as C/H/S IDE using a raid
 >controller, at sizes > 1Tb ?

him:

 >Nope, they are being presented as SCSI devices, but Solaris seems to
 >treat IDE drives as pseudo-SCSI devices, at least from the
 >programming point of view.

me:

 >Can you paste me a uname -a on the pertinent machine? I want to ask
 >a few people

him:

 >SunOS mariner 5.9 Generic_112233-11 sun4u sparc SUNW,Sun-Blade-100
 >
 >That''s the machine which has a Ultra-3 SCSI host adaptor to which
is
 >connected a RAID system.

me:

 >Any other information that you think is pertinent ?

him:

 >[it appears that] format can''t handle a drive bigger than
 >65535/128/128 (as that''s all the sd data structures can handle)
 >
 >Sorry [make that] cyl 65535 alt 2 hd 256 sec 128
 >
 >If it could handle 256 sectors per cylinder then it could cope with
 >up to 2TB.  Not that it''s a problem at the moment.  It''s
just a pity
 >that the underlying SCSI sub-system can''t handle device sizes
large
 >enough to handle the filesystems which can live on them.

Solaris 10 update 1 (1/06 release) supports SCSI disks larger than 2 TB.  I
believe that the same is true for IDE (as long as your controller supports
48-bit LBA).

The initial release of Solaris 10 has a 2 TB limit for 64-bit kernels, 1 TB for
32-bit kernels (or so the documentation claims, though this seems odd to me). 
Solaris 9, as of the 04/03 release (for many years, then) also has 2 TB support
on 64-bit kernels.

To use a disk this large, though, you need to use EFI labels -- it sounds like
your friend was using the standard VTOC.
 
 
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