Specifications

in the fibre-channel host supports the SCSI command Report LUNs, you can
configure all 4096 LUNs on the ESS to be accessible by that host. Otherwise, you
can configure no more than 256 of the LUNs in the ESS to be accessible by that
host.
FlashCopy and PPRC restrictions for open-systems hosts
When you copy a source volume to a target volume with FlashCopy or PPRC and
you require concurrent read/write access of both volumes, the source and target
volumes should be on different host systems. A copy operation with the target
volume and the source on the same host system creates a target volume with the
same identification as the source volume. The host system sees two identical
volumes.
When the copy operation creates the same identification for the target volume as
for the source volume, you cannot distinguish one from the other. Therefore, you
might not be able to access the original data.
Note: You cannot create a host target on a single Novell NetWare host system. For
Novell NetWare, the target volume must be attached to a second Novell
NetWare host system.
The target volume and the source volume can be on the same host system for a
PPRC or FlashCopy operation only under the following conditions:
v For AIX, when the host system is using a logical volume manager (LVM) with
recreatevg command support.
v For HP, when the host system is using LVM with the vfchigid -f command.
v For AIX and Sun when the host is not using an LVM.
v For any host system, when the host system can distinguish between a source
and a target volume that have the same identification.
LUN access modes
The following sections describe the LUN access modes for fibre-channel.
Fibre-channel access modes
The fibre-channel architecture allows any fibre-channel initiator to access any
fibre-channel device, without access restrictions. However, in some environments
this kind of flexibility can represent a security exposure. Therefore, the Enterprise
Storage Server allows you to restrict this type of access when IBM sets the access
mode for your ESS during initial configuration. There are two types of LUN access
modes:
1. Access-any mode
The access-any mode allows all fibre-channel attached host systems that do not
have an access profile to access all non-AS/400 iSeries open system logical
volumes that you have defined in the ESS.
Note: If you connect the ESS to more than one host system with multiple
platforms and use the access-any mode without setting up an access
profile for the hosts, the data in the LUN used by one open-systems host
might be inadvertently corrupted by a second open-systems host. Certain
host operating systems insist on overwriting specific LUN tracks during
the LUN discovery phase of the operating system start process.
2. Access-restricted mode
16 ESS Host Systems Attachment Guide