SQL Server / FAST Cache / EFD

Question

Our new VNX was setup with two different storage pools. One pool uses EFD and 15K SAS, the other uses SAS and NL-SAS.

We have a few MS SQL Server hosts with multiple LUNs. The LUNs are dedicated to either database files, transaction logs or tempdb.

I'm wondering if there is much of an advantage to keeping the transaction logs on the EFD pool, as the writes are generally sequential.

Is there a way to measure the IO profile of each LUN and see which types of IO gain the most from FAST Cache on EFD?

Roger_Wu · Answer

I'm not sure if we can see the IO types (random or sequential) on the storage. Maybe "Number of Stripe Crossing" in LUN Properties can tell you something (the more the number, the more the large IOs). But if you plan to do some tests, there is a way to get the performance data of your array.

Unisphere Analyze can help you get LUN's performance data, such as LUN Utilization, LUN Response Time, Disk Troughput/Bandiwdth, etc. But if Analyzer is not licensed on your array the archived performance log files (.nar) will be encrypted (.naz). NAZ files are for use by EMC support only, to assist with break/fix performance diagnostics. You might have to ask your sales manager for help, or submit a case to EMC support (only if you do meet the performance issue). Please refer to the video for the details: Next-Gen VNX Video: Unisphere Analyzer

VNX Monitoring and Reporting can do the samething. Refer to VNX Monitoring and Reporting - FREE 30 DAY TRIAL

dynamox · Answer

if VNX2, Monitoring and Reporting is free of charge, same goes for Analyzer.

landog1 · Answer

Thanks for the replies. But, how would it work? A SQL transaction log is writing new transactions sequentially. Would these writes always go to the highest performing storage in a pool?

Are there any general rules of thumb regarding where to save data files / transaction logs / tempdb files from MS SQL Server - given one pool with EFD storage and a second pool without?

I have similar questions concerning an Intersystems CACHE database, and its file systems.

Thanks for any insight you can provide.

Rainer_EMC · Answer

I would suggest to look at the available best practices and reference architecture on Powerlink for other SQL databases

VNX

SQL Server / FAST Cache / EFD

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