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SSD Q&A

1. Data capacity expectations for the next 5 years vs. hard drives. Best use in database systems.
[Pliant’s Answer] Capacity will follow the trend of NAND flash density, which doubles with each successive generation.  For database applications, we suggest putting “hot” or frequently accessed data on the EFD to boost performance.

2. When will SSD vendors finally beat it in the heads of their clients that the benefit of SSD is in database systems which are BCNF, thus removing orders of magnitude of stuff from the systems?  Use the SSD to refactor the databases to be lean and mean.
[Pliant’s Answer] Not sure if this was a question or a statement.  We agree with your statement.

3. SSD & RAID. Impact on individual IOP performance.  SATA vs. SAS SSD.  Half duplex spinning disk vs. full duplex SAS SSD. Drives with cache vs. drives without write cache. SLC vs. MLC & write performance differences. How to correctly test/benchmark the products? How to measure or predict product life span?
[Pliant’s Answer] RAID controllers have been masking the various mechanical latencies of the hard drives.  In many ways, the RAIDD controllers were spoon-feeding the hard drives with I/O requests.  In the short term we do see the current generation of RAID controllers, not having been optimized to work with solid state drives, will benchmark poorly, compared against non-RAID host bus adapters.

SAS is better suited, as an interface, to work with solid state drives.  SATA is a single-port, half-duplex interface so it can only read or write.  This works well with a hard drive since the hard drive is also physically limited to do either a read or a write at any given moment.  With a solid state drive, since there is no such physical limitation read and write operations can occur at the same time.  With SAS, there are two full-duplex ports as paths for these concurrent operations.

It takes longer to perform a Program/Erase cycle on a MLC flash, compared to SLC.  Therefore, solid state drives built using SLC will have better write performance.

Pliant believes benchmarks must measure sustained performance.  Many solid state drives on the market today show good performance when new but show performance degradation over time.  It is therefore very important to measure the performance data over a period of 12 hours and more.  At the same time, since in the datacenter, solid state drives are meant to replace multiple drives, it is important to benchmark using many concurrent read and write operations to gauge the solid state drive’s ability.

For lifespan, a good indication is the limitation of writes.  Many solid state drive vendors do not have the ability to manage the flash media and therefore must either retire usable blocks early or limit the amount of customer writes, or both.  The Pliant Lightning family of Enterprise Flash Drives imposes no such limitation.

4. SSD reliability SSD RAID long term storage - 500 GB hybrid SSD/HDD devices and or systems
[Pliant’s Answer] The Pliant Lightning family of Enterprise Flash Drives are designed for a 7-year lifespan and warranted for 5 years.  The 5-year warranty period is consistent with the industry norm for hard disk drives.  The differentiation for Pliant is that the Lightning Enterprise Flash Drives does not have a daily limit on the amount of writes.

5. Would be interested in hearing about the right balance of price/performance for SSD/HDD in enterprise vs. consumer and how it might change based on flash pricing and tech trends over the next 5 years.
[Pliant’s Answer] As a one-to-one replacement, solid state drive is a poor choice for the desktop/notebook consumer segment of the market.  The exception is where there are specific shock & vibration requirements where hard drive cannot match solid state drives.  Even then, the pricing will not reach a point where the solid state drive will completely replace the hard drive.

In the enterprise, using the Pliant Enterprise Flash Drive for “hot” or frequently accessed data, while using larger capacity, lower-RPM hard drives can provide a significant cost and operational saving.

6. SSD; a part of storage hierarchy or 1:1 replacement of HDD?
[Pliant’s Answer] Please see answer above.

7. SSD comparison to HHD?
[Pliant’s Answer] This would be an apples-to-oranges comparison.  One solid state disk is meant to replace many hard drives, in terms of performance.  On a high level:

  • Hard drive is limited by a single read/write head while solid state drive has many virtual read/write heads.
  • Hard drive is more susceptible to negative effects shock & vibration than a solid state drive.
  • Hard drive consumes more power than a solid state drive.

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