Chapter 6. Host configuration 113
Draft Document for Review August 30, 2007 12:59 am 7065HostConfig.fm
As you can see in Figure 6-3, the multipath support component is referred to as
Storage
Manager 2 RDAC
in the installation wizard. If you are already familiar with the IBM System
Storage DS4000, then you will know that the DS4000 RDAC is a proprietary multipath
solution specific to DS4000. It does not use Microsoft MPIO.
The DS3000 Storage Manager RDAC on the other hand is a very different implementation
altogether. It consists of Microsoft MPIO and the DS3000 DSM.
The DS3000 DSM consists of the following two drivers:
ds4dsm.sys
ds4utm.sys
The driver names suggest that this DSM solution supports DS4000 storage subsystems as
well. This is indeed true - DS3000 DSM actually does support both the DS3000 and DS4000
storage subsystems. But remember, this is not the same as the proprietary DS4000 RDAC
package.
Let’s summarize:
DS4000 subsystems can work either with the proprietary DS4000 RDAC or with the
Microsoft MPIO compatible DSM.
DS3000 subsystems should use the Microsoft MPIO compatible DSM only. Incidentally,
the DS3000 DSM is called RDAC, but has nothing in common with the DS4000 RDAC.
6.2.2 Linux RDAC
Linux RDAC is not included with DS3000 Storage Manager for Linux - it is a separate
package, also known as the MPP driver. It consists of two parts:
mppUpper and mppVhba
(virtual HBA).
You can download the RDAC package from the following Web site:
http://www.lsi.com/rdac/ds3000.html
Alternatively, you can start by visiting the IBM Systems support Web site, however you will
eventually be redirected to the URL listed above.
There are two different Linux RDAC packages: one for kernel version 2.4 and the other for
version 2.6.
The packages each contain a compressed tar file of the source code for the RDAC driver. Use
the package to build the RDAC kernel driver by carefully following instructions in the readme
file.
As the multipath and failover functionality will be provided by RDAC, it is important that you
use non-failover with your HBA. Linux RDAC cannot coexist with failover HBA drivers.
You should also make sure each HBA in the host server only sees one DS3000 RAID
controller. If any individual HBA has access to both controllers, then the RDAC driver will not
work properly. To prevent this, make sure you implement correct zoning on the SAN switch (in
the case of FC HBAs and DS3400).
Another important consideration is the order of LUNs assigned through host-to-logical-drive
mapping. The LUNs assigned to a Linux host must be a contiguous set of numbers, because
by default, the Linux kernel does not detect so-called
sparse LUNs - that is, it does not scan
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