O SSD – Solid State Drive, ou disco de estado sólido, nada mais é que um “pen-drivão”. É uma unidade de Persistent storage that has no moving parts. They are more durable than HDDs, consume less energy (they’re green!), do not generate vibrations, can operate at higher temperatures, and above all: they are much faster than current HDDs. There is no SCSI or SAS that is faster than a professional SSD.
The only disadvantage of this beauty “was” the price. Yes, it was, because since 2010 the production and use of SSDs have scaled up, and therefore prices on the shelves have decreased.
I have been recommending the use of SSDs to increase the capacity of MySQL databases with very high write incidence with great success. The idea here is, if SSDs are much faster than HDDs, they can write much more per unit of time. Therefore, MySQL eliminates a known “bottleneck” and increases its write capacity on a single (master) server.
But, as everything good is invariably scarce (RAM, fiber optics, SSD, cold beer, and beautiful women)! That’s why I recommend using these guys only to store the datadir (assuming you are a cool guy and don’t write any logs inside your data directory). SSDs are still not as generous as HDDs in terms of space.
Why and when to use SSD?
SSD is much faster and safer than HDDs. It is the next generation in data storage. HDD is stuff from the last century. It should indeed be used when: a) your database fits on it :), and b) your database suffers a high amount of concurrency, notably writes, and all tuning and scale-out measures have already been taken and more performance is required. It is also important to say that more performance is required without increasing the solution’s complexity.
When not to use?
When it doesn’t fit in your budget! When the database does not fit entirely on the SSD. Doing sharding or partitioning of the database and still using SSD, I think that is too much. Maybe in the future. Today, I don’t recommend it. It’s like paying a lot for a complex solution. Always remember the 3S rule = “Stay Simple Stupid”.
I have helped implement this solution in 3 companies in Brazil and 2 in the USA. All 5 are happy and have not looked back.
Precautions when purchasing SSD drives:
Avoid traditional desktop peripherals — it is a common mistake, especially in SMB companies. Doing this risks only slightly better performance while paying much more.
Prefer PCI-Express drives instead of SATA. Latency is much lower, meaning the drive is much faster.
Beware! Some drives are fantastic for reading but terrible for writing. The decision to use an SSD should always be because of the write performance, not the read.
Please choose one 100% compatible with your operating system.
The two brands I recommend are OCZ (http://www.ocztechnology.com/) and Virident (http://www.virident.com/). Virident is a company with tradition producing appliances for MySQL (and other databases). OCZ is my personal preference.
Just for comparison, see this chart comparing an HDD against an OCZ Intrepid SSD:
And regarding energy consumption:
The OCZ Intrepid line comes in sizes from 256GB to 2TB. It is not the cheapest product from OCZ, but by far the most recommended for databases that need a big boost in write performance.
Conclusion:
If you don’t want to complicate your environment with multi-master setups or use third-party software to increase write capacity, your solution is called SSD. Simple as that.
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