White Papers
11 Best Practices for Deploying a Mixed 1Gb/10Gb Ethernet SAN using Dell Storage PS Series Arrays | BP1008
4 Pool architecture and volume placement testing
When integrating 10Gb arrays into existing 1Gb PS Series SANs you must also consider how you locate
volumes within the available pools. This section focuses on answering two key questions:
Will you get better performance having 1Gb initiators access volumes on 10Gb arrays?
Do you place 10Gb arrays in the same pools as existing 1Gb arrays?
PS Series arrays are very flexible in regards to their configuration—up to and including the placement of
arrays into storage pools. The pool is a very important construct within a PS Series SAN, as they control the
load balancing of volumes across multiple arrays, redundancy among those arrays, and inter-array
communication.
It is possible to place arrays with different speed controllers in the same pool. But is it advisable to do so?
This question has become important, as customers now have the ability to add 10Gb arrays into existing 1Gb
SANs.
To provide answers to these questions, three I/O workloads (see Table 1) were run against different
configurations of volumes and pools. Each workload was run three times for 15 minutes, then average I/O
performance data was calculated. The goal was to measure performance differences between same speed
pools and the mixed speed pools.
Workloads
Workload type
Block size
Read/Write ratio
Sequential read
256 K
100% / 0%
Sequential write
64 K
0% / 100%
Random read/write
8 K
67% / 33%
The tests performed for this paper use the split connect LAG method (shown in section 3.2) for connecting the
1Gb and 10Gb switch fabrics. The test information and results have been brought forward from the previous
version of this paper as there have been no changes in the PS Series storage architecture that would
significantly change these results. As such, at the time of testing, the 10Gb switches used did not support
stacking.
4.1 Comparing pool design and volume placement: 1Gb host initiator
Note: These test results were brought forward from the previous version of this paper. Best practice
recommendations remain the same with update PS Series storage.
Tests for 1Gb initiator IO paths:
A: One PowerEdge server with two 1Gb SAN ports connecting to four volumes in one PS Series 1Gb
array through stacked Dell Networking N3000 Series switches.