I'll take this one but only because I beat Pete to it. :-)
The correct answer is: "It Depends."
You have choices, many choices.
First you need disk for VIOS. Preferably a mirrored pair of disks. These
disks should NOT be used to host other O/S storage but CAN be used for
image catalogs (Install and PTF for example.)
Single VIOS:
- You can simply RAID the remaining disks in VIOS which then creates
one large 'Volume Group' for each RAID set. With 32 disks that will
likely be at least 2 likely three volumes. In this scenario you would
use VIOS commands to create 'File Backed Logical Volumes' (LUNS) on
these Volume Groups. You make the call on size and quantity. These are
then mapped to a virtual host adapter (or adapters) making them
available to IBM i.
- You can NOT due RAID and simply map each physical drive directly
up to IBM i. You should consider that this means there is no disk
protection. In this case you would use IBM i Disk mirroring for
protection. Depending on how you map this and how many RAID cards you
have for VIOS this could be LUN level, Bus Level or even Loop Level
protection - all defined by the design of your hardware.
Dual VIOS:
(Note this requires a complete duplicate set of RAID cards and disk
drawers and units assigned to the second VIOS partition.)
- You can RAID the remaining disks in VIOS which then creates one
large 'Volume Group' for each RAID set. Use VIOS commands to create
'File Backed Logical Volumes' (LUNS) on these Volume Groups. These are
then mapped to a virtual host adapter (or adapters) making them
available to IBM i. NOW the main reason for doing DUAL VIOS is for
redundancy so you would mirror these LUNS in IBM i to the other copy of
VIOS. You would have Mirrored RAID drives in this scenario but it means
when you're running on one or the other copy of VIOS solo you still have
disk protection. You spend more on hardware and disks of course and pay
an I/O penalty of Mirror + RAID.
- You can NOT due RAID and simply map each physical drive directly
up to IBM i. You would use IBM i Disk mirroring for protection here as
well. This would be the best performer of the group with the least
overhead for VIOS but still the protection of dual VIOS partitions.
- Larry "DrFranken" Bolhuis
On 7/29/2011 5:44 PM, Kirk Goins wrote:
There has been talk here lately on when you Host an IBM i Partition on top
of an IBM Partition you should create multiple storage spaces so the Guest
thinks it has lots of disk arms vs 1 single large storage space ( ie 1 disk
). I get that concept and the reasons behind it.
Now if I decide to use VIOS and not attach to a SAN, but use 32 139GB
internal disks, how does VIOS divide up the disk to the IBM i partitions on
top? Whole Disks? How is Protection, like Raid5 handled?
Thanks
midrange.com
