Zoning is not physical separation
anthonyv 2000004B9K Comments (3) Visits (6973)
I see this comment occasionally and it makes me bristle:
"Disk and tape traffic must be in separate zones because they have different characteristics. If they are in the same zone this can cause performance problems or have other adverse affects."
True statement or totally wrong?
Well actually kinda wrong... If you have a single HBA with only one port, then separating disk and tape traffic into separate zones does NOTHING to get around the fact that both streams of traffic (random bursty disk traffic and sequential streaming tape traffic) are all coming from or going to the same HBA port. All zoning achieves in this case is stop the disk and tape devices from talking to each other (something that in general they are not interested in doing).
Separating disk and tape traffic is best done with separate HBA ports (whether thats a dual ported HBA or two single port HBAs).
So lets change the wording:
"Disk and tape traffic should ideally be handled by separate HBA ports, because they have different characteristics. If both traffic types use the same HBA port this can cause performance problems or have other adverse affects."
Guess what? This advice has not changed since 2001.