Specifications
Escala Tower PL & S, E, T System Hardware
Chapter 3: External Storage and SAN Subsystems 51/116
9es3s1c3.doc
Rev 5.9
02/12/2003
4.4. DAS Manager and ArrayGuide
DAS Manager and ArrayGuide support only the DAS 1000, 2000, and 3000 Series.
The DAS 1000, 2000 and 3000 Series Storage System Manager (DASMGR) software, is an integrated
set of utilities that allow users to configure the array, monitor the status of the major storage system
components, and download updates of the arrays internal microcode. DASMGR is delivered with AIX
version 4.
In addition we can take advantage of a new graphic array management tool simplifying day-to-day
operational tasks. Called ArrayGUIde, this tool is basically available and requires a graphical color
display on the host or somewhere on a LAN connected to the host.
4.5. ATF
ATF V2.1 & ATF V2.2 Discontinued : December 31, 2003
ATF, Application Transparent Failover is a host based software, running on Escala servers, which
delivers uninterrupted information access to DAS subsystems equipped with dual storage processors.
ATF delivers automatic rerouting of I/O traffic in the event of a host-to-storage path failure. Failover
to a redundant I/O path is transparent to the server's application software and users. With ATF,
production is not impacted by the failure of a cable, host bus adapter or storage processor. Instead, data
continues to be delivered without interruption. ATF ensures that no I/O is lost.
Storage
Application
disk1 disk2
SP A SP B
ATF
Server
Application
disk1 disk2
SP A SP B
ATF
1
2
1
2
HBA failure
Cable failure
Storage Processor failure
I/O path
Load balancing
dual active SP
I/O rerouted
single active SP
In the unlikely event of a failure, the failover occurs in seconds, permitting continuous access to the
information stored on the disk subsystem(s). Without the user intervention, ATF reconfigures the
RAID subsystem (e.g. bind the LUNs to the surviving SP), retrieves I/Os in the mirrored write cache
and completes them, and finally, on the server it self, route the I/O through a secondary path to the
surviving (provided that the server is equipped with two fibre channel adapters).