Re: Filer storage for databases, seriously? (Was: Re: NetApp ques tions)

From: Aaron Sherman (ajs@ajs.com)
Date: Thu Aug 10 2000 - 16:37:41 EDT

  • Next message: Yoder, Alan: "RE: Filer storage for databases, seriously? (Was: Re: NetApp ques tions)"

    On Thu, Aug 10, 2000 at 12:01:03PM -0500, Jay Orr wrote:

    > Yes, latency is a big factor, but wasn't the question about directly
    > connected RAID (or a SAN) vs. a filer? Since both are raided, the latency
    > would be roughly equal.

    But they're not.

    Why?

    Mostly, I suspect, because of the journaling. A good journaling
    filesystem on a locally-attached RAID 5 (or 4, if you get around the
    performance problems the way NetApp has) disk array with lots of RAM
    cache for the journal would probably at least match, and likely
    outstrip the NetApp's performance.

    Keep in mind also that the NetApp can play fast-and-loose with it's
    journal-commits because it's all in NVRAM, so it does not commit
    before returning success to the client. That HAS to be a big win. 

    -- 
Aaron Sherman
Systems Architect
HighWired.com -- The global high school community
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