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Resumen del manual
MPE Mirrored Disk/iX
Though mirrored disk is not an array it is the lowest level entry into high availability data protection. This
technology is based on (SCSI) JBOD and relies on having a single piece of data (file) written to two
different disks that are on two separate paths. This method protects the data from any single point of
failure along the I/O path. The greatest advantage of this technology is its small cost to implement.
The downside of this technology is that it can disable itself under high I/O loads which leave the user
unprotected. These false failures can also lead to long recovery times which also leave the user
unprotected. For this and other reasons the MPE/iX R&D Lab does not recommend this solution for
environments where there is a great deal of I/O activity or where the disk capacity exceeds 50Gbytes of
protected storage.
VA7xxx Storage Arrays
These are HP's entry and mid-range fibre channel high availability storage arrays. The VA7100 (now
discontinued) is a dual controller (active/passive) 1Gbit fibre channel array that is only slightly faster than
the 12H AutoRAID but has much more features and is easier to manage.
All VA7xxx storage arrays must be ordered with dual controllers for MPE/iX and MPE/iX requires that a
VA manage software package called the CommandView SDM, to configure and monitor the VA, be on a
separate PC workstation or HP-UX server attached to the VA storage array.
For older NIO based HP e3000s the A5814A (option #003) Fabric Router can be used to connect the fibre
channel arrays to the older SCSI based NIO HP e3000s. (See the ha & storage matrix for support
information.)
The VA7110 and VA7410 are HP's newer entry and mid-range virtual arrays. Both these arrays support
2Gbit redundant controllers. The VA7410 (mid-range array) is better suited for heterogeneous
connections but still don't perform as well as some (Ultra-SCSI JBOD) Mirrored Disk/iX solutions. What
you do get is added hardware reliability, added data protection and ease of management because most
array component failures (disk or media problems) are handled transparently by the array. Adding MPE's
High Availability Failover/iX increases availability to both the VA7110 and VA7410 by protecting the
I/O path components between the HP e3000 and the storage array.
Purchasing array controllers with as much memory cache as possible is important along with making sure
there is enough available server memory for MPE/iX so that it does not have to go to disk will help
improve the performance picture.
There have been a number of VA7xxx configuration change recommendations issued by HP that help to
resolve HP-UX problems that if implemented on arrays attached to the HP e3000 have caused major
performance problems. One such change describes reducing the Queue Depth of the VA from the default
value of 750 and to set it to a very small number. This change solves an I/O saturation problem when HP-
UX issues too many I/O requests for the VA to handle. MPE handles its own requests and will only issue
8 I/O requests for each MPE/iX configured Ldev. The "Queue Full" message is an unexpected error and at
best MPE/iX will stop all I/Os on that bus (I/O pathway), abort all those pending I/O requests, reset and
clear the bus and then restart all those pending I/Os each time it encounters this error message or worse do
a System Abort if this reset and I/O restart happens during critical operating system I/O.
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Software - MPE/iX 7.5 Operating System (154.41 kb)