Lukas,
On 4/16/2010 3:09 PM, Lukas Beeler wrote:
<snip> IBM has severely
restricted SAN support for the IBM i platform (so that they can
continue selling overpriced disks).
This is absolutely false.
0) Testing. Until they know how a SAN performs and runs under stress
it will not be supported.
1) IBM i now separate from the hardware. This was completed with the
merger of i and p forming the current POWER Systems product line. IBM i
does not get revenue from selling disks and as such has no interest in
'Selling overpriced disks.'
2) Testing. In order to be supported it must be tested.
3) IBM i uses different sector sizes than other operating systems. As
such VIOS must be in play in order to handle this mapping. This does not
constitute 'Severely Restricting'. Besides that essentially minor
function, VIOS brings other benefits especially for large shops.
4) Testing. In order to understand how the SAN needs to be configured
to support IBM i it must be tested.
5) IBM i does things other operating systems do not such as
scattering data across all available arms. Thus with IBM i RAID 5 is
truly RAID 10. This scatter loading combined with it's capability to do
huge amounts of I/O means that not just any SAN will work well with our
operating system. Like the complaints I've seen on this list about a two
drive POWER6 system performing horribly (as I would expect it to) an
improper SAN solution would do the same.
6) Testing. In order to know where a particular SAN fits into the
bigger picture of IBM i it must be tested.
You may think I jest about testing but this is one of the strong suits
of IBM i and the hardware on which we run it. I have been told by people
in Rochester that many additional SANS will work with IBM i. They have
even mentioned some units they have seen connected and they work.
However until they complete testing those units are unsupported. They
have a list of SANs to test and will work down that list as resources
allow. They will never support all SANs.
- Larry Bolhuis
midrange.com
