HP StorageWorks SAN Virtualization Services Platform Best Practices Guide (5697-0935, May 2011)

EVA side
Each DPM quad is specified as a host:
• Primary DPM, first quad: DPMA1_Q1; dpm_21; dpm_23
• Secondary DPM, first quad: DPMA2_Q1; dpm_41; dpm_43
• Primary DPM, second quad: DPMA1_Q2; dpm_25; dpm_27
• Secondary DPM, second quad: DPMA2_Q2; dpm_45; dpm_47
Red virtual disk
• RAID1|RAID5|RAID6 (all virtual disks must have same RAID level); Path Controller A; mapped
to DPMA1_Q1, DPMA2_Q1
• Size: between 100 GB and 750 GB, depending on initial pool size (800 GB – 6 TB)
Green virtual disk
• RAID = same as red virtual disk; Path Controller B; mapped to DPMA1_Q2, DPMA2_Q2
• Size: same as red virtual disk
Grey virtual disk (pool extension)
• RAID = same as red virtual disk
• size: Depends on Pool extension, all virtual disks in extension must be the same size)
• Mapped in the same manner as red and green virtual disks
NOTE: For bigger pools or environments, the number of back-end LUs should be 16. The maximum
size for an EVA virtual disk is 2047 GB. You can add DPM quads to distribute the EVA virtual
disk.
Improving synchronous mirroring performance
To improve synchronous mirror performance:
• Determine if the application will be throttled to an unacceptable level (for the user and for the
application). The one way latency is 0.5 ms over Fibre Channel, which equates to about 100
KM. No Fibre Channel over IP converters are supported today. If support comes in the future,
the converters will add a delay for converting two times, plus the IP link delay per round trip.
• The SVSP has to be sized correctly by using the latest performance information.
• Consider the desired behavior and performance during failure events, such as fabric failure,
site failure, and recovery to the same site or new site.
• Consider ISLs for failover characteristics, bandwidth characteristics, and their event notification
properties.
• Consider I/O bursts that overwhelm the SAN containing SVSP, because SVSP processes I/O
without buffering, causing major SAN issues, and lower performance. Bursts can be controlled
by restricting adapter queue depth, but may require monitoring.
• With HP Services:
HP can assess the viability of using synchronous mirrors by analyzing the write bytes/sec
and writes/sec for applications. You plan your SVSP implement and ensure you have the
◦
proper number of DPM quads and if necessary, add striping across quads for
write-intensive LUNs that cannot operate with a single quad.
◦ HP can recommend the type of storage pools that will be most efficient based upon the
type of arrays and their characteristics.
46 Synchronous mirroring