12h Autoraid

[#1]

I know the way hot to get good performens.
The way is:
1) Create each vg comprised of 2 LUNS of equal size. LUNa should be primary path controller X (alt Y); LUNb should be primary path controller Y (alt X). This utilizes both external SCSI paths for maximum performance.
2) Each lvol should be striped across both LUNS in the volume group for the same reason.
3) As you indicated, run them at about (50-60%) capacity leaving the remainder as unconfigured LUNS. Yes, you waste disk but the performance is worth it.

But my question is must be the 2 LUNS in the vg of equal size?????
Thanks

[Eugeny Brychkov]

See 'man lvcreate'. Striping is done at lvol level. If you will have LUNs of different sizes then you will not be able to stripe lvol across space difference - this means that striped lvol can be of size of the least LUN (in your 2-LUN config, thus '-i 2')
Eugeny