This is Part 7 in an ongoing series on disk performance. You can read the entire series by starting at the Introduction.
For the last 7 or so years the PowerVault 220S was Dell's offering in DASD enclosures. It supports 14 SCSI drives and can run in split bus mode with 7 drives per SCSI bus. It's since been replaced by the PowerVault MD1000 which supports 15 SAS\SATA drives and can also run in split bus mode with 7 drives on one bus and 8 drives on the other. I recently had the opportunity to run tests against both models to see how they compare against one another. I didn't have too long with them so I was only able to test RAID 10 and RAID 5 before I had to put them back into action in production.
The PowerVault 220S tests were run using 12 146 GB 15K RPM Ultra320 SCSI drives and the enclosure was connected to a PowerEdge 2850 via a PERC 4/DC controller card. The PowerVault MD1000 tests were run using 12 146 GB 15K RPM SAS drives and the enclosure was connected to a PowerEdge 2950 via a PERC 5/E controller card. Tests were done against each enclosure in split bus mode using a 64 KB RAID stripe, 64 KB allocation unit size, and partition offsets of 32 KB, 64 KB, and 1024 KB. To see how each system scaled under load I ran separate tests with 4, 8, and 16 threads with an IO queue depth of 8 against a 512 GB data file. You can view the specifics of each setup here.
PowerVault 220S – RAID 10
Here's what 8 KB random reads look like:
And here's what 8 KB random writes look like:
PowerVault 220S – RAID 5
Here's what 8 KB random reads look like:
And here's what 8 KB random writes look like:
PowerVault MD1000 – RAID 10
Here's what 8 KB random reads look like:
And here's what 8 KB random writes look like:
PowerVault MD1000 – RAID 5
Here's what 8 KB random reads look like:
And here’s what 8 KB random writes look like:
Head To Head - RAID 10
Now for fun I’ll look at a head to head RAID 10 matchup of the 220S against the MD1000. These comparisons use the same testing parameters I outlined at the top of this post except that I am focusing only on a 64 KB partition offset this time.
Here’s what 8 KB random reads look like:
And here’s what 8 KB random writes look like:
Head To Head - RAID 5
Here’s what 8 KB random reads look like:
And here’s what 8 KB random writes look like:
Conclusion
No surprises here, the newer controller card and faster drives in the PowerVault MD1000 outperformed the PowerVault 220S. The chart below shows the MD1000’s performance metrics as a percentage relative to the 220S. Recall that for average latency lower values mean better performance so a negative number indicates a decrease in latency (which is good)
In Part 8 I will wrap things up and recap the conclusions reached in Parts 1-7.
About Kendal
Kendal is a database strategist, community advocate, public speaker, and blogger. A practiced IT professional with over 15 years of SQL Server experience, Kendal excels at disaster recovery, high availability planning/implementation, & debugging/troubleshooting mission critical SQL Server environments. Kendal is a Senior Consultant on the Microsoft Premier Developer Support team and President of MagicPASS, the Orlando, FL based chapter of PASS. Before joining Microsoft, Kendal was a SQL Server/Data Platform MVP from 2011-2016.
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