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SAN Configuration

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  • 1.  SAN Configuration

    Posted 04-13-2015 01:43:00 PM
    Currently running a POC of Delphix. The Delphix Engine is using 3 LUNs on a EMC VNX5600 8 disk RAID 1/0 15K drives the OS sits on a different set of disks, and the array has FAST Cache enabled. The Delphix IO test pretty much failed miserably on the writes. The array is not heavily used, is it recommended to have FAST Cache turned off on the storage pool for the Delphix Engine? Is the 8 disk RAID 1/0 too few disks?
    #Tip


  • 2.  RE: SAN Configuration
    Best Answer

    Posted 04-13-2015 02:23:00 PM
    Hey Andy. The first concern is that we we want to maximize the throughput of the VM by having a minimum of 4 SCSI virtual controllers, which means a minimum of 4 LUNs for storage in addition to the LUN for the system partition. I don't know what your current throughput/IOPS are in your lower/test environment, and we should ideally have that before giving you specific recommendations about the number of LUNs or minimum IOPS. That said, keep in mind the Delphix engine is acting as storage appliance for all the downstream target DB servers, so throughput/IOPS is very important.

    Should you add more drives? Yes. If you don't get decent IO results from our test, we would not expect you to be satisfied with the results. I would like to see you getting "A"s and "B"s across the board from our test script to ensure that when you are using Delphix, you and the folks leveraging the product get the responsiveness expected from the application. 

    I would also mention the RAM on the Delphix engine should typically be at least 128GB. We see performance gains as more RAM is added significantly above that. Sometimes more than one run of the test is needed if dynamic SAN tiering is enabled, or to take full advantage of caching. If you can bump on the tier (SAS or SSD vs SATA), that would help too, obviously.

    You didn't mention the storage connection, whether that's FC or some other method? Do you have <10ms latency on the storage?

    These thoughts should get you started. If you have a particular SE you've been working with they can reach out to me for more detail if that helps.

    Joel



  • 3.  RE: SAN Configuration

    Posted 04-13-2015 02:32:00 PM
    Thanks for the reply Joel! We are using FCoE for connectivity to the storage array.  We scored D- on most of the write tests, read tests were mix of A- and B-. The part about re-running the test makes sense as EMC FASTCache needs a "warm-up" period to understand the workload and cache items.  I think we just may be short of spindles to satisfy the throughput of the test.