Revisiting RAID

JosephGress
JosephGress Member Posts: 36
edited 2013-08-17 in NAV/Navision Classic Client
When clients have asked for recommendations regarding disk drive configurations for NAV SQL, I have advised most to use some variation of the following setup:

Three Logical Drives (each on dedicated spindles):
C: OS, Program Files, Master, Model, MSDB and tempdb SQL databases) (RAID 1)
D: NAV Database (mdf and ndf files) (RAID 1 or RAID 10)
E: NAV Transaction Log (RAID 1 or RAID 10)

Recently, one of my clients asked whether it would be better to put all of the drives on one big RAID 10 array. He pointed out the following article:

http://www.smbitjournal.com/2012/11/one ... er-storage

I would like to quote briefly from this article: "The only significant factor, that has not been mentioned, for which split arrays were traditionally seen as beneficial is access contention – the need for different processes to need access to different parts of the disk at the same time causing the drive head to move around in a less than ideal pattern reducing drive performance. Contention was a big deal in the late 1990s when the old rule of thumb was developed."

The article continues: "Today, drive contention still exists but has been heavily mitigated by the use of large RAID caches. ... These can easily add hundreds of gigabytes of extremely high speed cache that can buffer nearly any spindle operation from needing to worry about contention. So the issue of contention has been solved in other ways over the years but has, like other technology changes, effectively freed us from the traditional concerns requiring us to split arrays."

That argument is pretty compelling.

Is it time for me to change my recommendations?
Joseph Gress

Comments

  • David_Singleton
    David_Singleton Member Posts: 5,479
    Yes. :mrgreen:
    David Singleton
  • bbrown
    bbrown Member Posts: 3,268
    I'd say it depends. Not all servers are the same. I would not agree that the 1-2 GB controllers are very common in typical NAV systems. I don't think you can broadly apply the assumptions of this article to the whole of the NAV world.

    I also see the article never quite defines what is meant by "a large RAID 10". How many drives are they talking about? Is it a number that would be typical?
    There are no bugs - only undocumented features.

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