Re: SSD Drives

Steve Crawford <scrawford@xxxxxxxxxxxxxxxxxxxx> · Fri, 04 Apr 2014 09:04:01 -0700



    On 04/03/2014 12:44 PM, Brent Wood
      wrote:

    
      Hi David,

        
        Does the RAID 1 array give any performance benefits over a
        single drive? I'd guess that writes may be slower, reads may be
        faster (if balanced) but data security is improved.

      
    I've been looking into upgrading to SSD and wondering about RAID and
    where to apply $$$ as well. In particular I'm curious about any
    real-world PostgreSQL-oriented performance and data-protections
    advice in the following areas:

    
    1. With SSDs being orders of magnitude faster than spinning media,
    when does the RAID controller rather than the storage become the
    bottleneck?

    
    2. Do I need both BBU on the RAID *and* capacitor on the SSD or just
    on one? Which one? I'm suspecting capacitor on the SSD and
    write-through on the RAID.

    
    2. Current thoughts on hardware vs. software RAID - especially since
    many of the current SSD solutions plug straight into the bus.

    
    3. Potential issues or conflicts with SSD-specific requirements like
    TRIM.

    
    4. Manufacturers, models or technologies to seek out or avoid.

    
    5. At what point do we consider the RAID controller an additional
    SPOF that decreases instead of increases reliability?

    
    6. Thoughts on "best bang for the buck?" For example, am I better
    off dropping the RAID cards and additional drives and instead adding
    another standby server?

    
    Cheers,

    Steve