HP StorageWorks Modular Smart Array 1000 Configuration Procedures for HP-UX Addendum (365448-001, April 2004)

Important MSA1000 HP-UX support notes
3Modular Smart Array 1000 Configuration Procedures - for HP-UX Addendum
■ LUN configuration notes:
— A minimum of one storage LUN on the MSA1000 must be configured and set to the
HP-UX host mode before connecting the MSA1000 to the HP-UX server.
— Set the ratio of read cache to write cache to prioritize writing in RAID 1, RAID 1+0,
RAID 5, and RAID ADG configurations to improve non-random write performance.
— Set the controller rebuild priority to medium or high to minimize exposure during a drive
rebuild. During a drive rebuild, limit I/O activity from the attached servers.
— When determining how many hard drives to include in an array and how many LUNs to
create from that array, consider the I/O load of the data that will be stored on those LUNs.
In general, striping an array across many hard drives increases the total throughput on that
array and delivers better I/O performance, but there is a performance trade-off when an
array is divided into multiple LUNs. Too many LUNs on the same group of hard drives
causes more drive seeking and a loss of throughput.
— When assigning a RAID level to a LUN, consider the required level of fault tolerance and
performance for the data on that LUN.
The following supported RAID types offer differing levels of fault tolerance and
performance:
— RAID 0 - data striping only
(no fault tolerance - highest I/O performance)
— RAID 1 (RAID 1+0) - drive mirroring (data striping and drive mirroring)
(high fault tolerance - high I/O performance)
— RAID 5 - distributed data guarding, with distributed parity data
— RAID ADG - Advanced Data Guarding, with two sets of distributed parity
(high fault tolerance - low performance)
— In configurations where the server operating system resides on a LUN within the
MSA1000, do not share other LUNs on that array with other servers.