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Re: Ssd vs mix of ssd and spinning disk




Hi Shain,

On 5/8/2017 1:53 PM, Shain Miley wrote:
Hello,
We have traditionally setup our mysql database servers with a mix of ssd and spinning disk drives.

We use the ssd drives (Raid-1) for the mysql tablespace data, and we use the spinning disks (15 sas in Raid-1) for the index data, etc.

I am wondering if going forward we should simply put all of the data on the ssd drives. Does anyone have any information on whether or not we would see any significant performance increase if we made this switch?

I have been thinking about using 4 ssd drives (Raid-10) going forward…and wondering if we should expect to see any improvement in the database performance.

Any thoughts?

Thanks in advance,

Shain


If you would benefit from shifting storage technologies depends on how limiting your current devices are to your overall throughput.

In most cases, workloads are either CPU-bound (normally due to poor choices in table design or query patterns) or DISK-bound (too many reads and writes, i/o requests, for the device to keep up).

Occasionally systems become MEMORY-bound (normally due to poor configuration choices which push the system to using swap) or NETWORK-bound (the number of concurrent network round trips to complete a task is higher than the components can handle).


Of those 4 situations, which is contributing most to your total response latency?

For example, are you spending more time waiting for data to be buffered in from disk than you are computing and returning the results? If so, faster disks could help temporarily.

What may help more (and for a longer time) is to improve your storage and retrieval patterns (table and query designs) to require less frequent trips to disk (aka, better buffering) or to need smaller slices of each table (more selective indexes, querying for fewer columns, sharding tables, sharding data to different instances, partitioning data, ... ).


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Shawn Green
MySQL Senior Principal Technical Support Engineer
Oracle USA, Inc. - Integrated Cloud Applications & Platform Services
Office: Blountville, TN

Become certified in MySQL! Visit https://www.mysql.com/certification/ for details.

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