Is there still a reason to choose a 10,000 RPM hard drive over an SSD?

Solution 1:

This is a velociraptor. As you may notice, it's a 1tb, 2.5 inch drive inside a massive heatsink meant to cool it down. In essence, it's an 'overclocked' 2.5 inch drive. You end up having the worst of all worlds. It's not as fast at random reads/writes as an SSD in many cases, it doesn't match the storage density of a 3.5 inch drive (which goes up to 3-4 tb on consumer drives, and there's 6 tb and bigger enterprise drives).

An SSD would run cooler, have better random access speeds, and probably have better performance, especially where the equivalent SSD, while costlier, is likely to be a higher end one, and SSDs generally have better speeds as they get bigger.

A normal HDD would also run cooler, have better storage density (With the same 1tb space fitting into a 2.5 inch slot easily), and cost per mb/gb would be lower. You might also have the option of running these as a raid array to make up for the performance deficiencies.

The comments also indicate that these hard drives are loud in general - SSDs have no moving parts (so, they are silent in normal operation), and my 7200 RPM drives seem quiet enough. Its something worth considering when building a system for personal use.

Taking all this into account, with a sensible planned upgrade path, and endurance tests demolishing the myth that SSDs die early, I wouldn't think so. The thinking enthusiast would use an SSD for boot, OS and software, and a regular spinning hard drive for bulk storage, rather than picking something that tries to do everything, but doesn't do it quite as well, or cheaply.

As an aside, in many cases, 10K RPM enterprise drives are getting replaced by SSDs, especially for things like databases.

Solution 2:

Not sure these justify picking a hard drive over a NAND-Flash SSD, but they are certainly areas that a 10,000 rpm hard drive would offer benefits over one.

1. Write amplification. Hard drives can directly over-write a sector, but NAND-Flash SSDs cannot overwrite a page. The entire block must be erased, and then the page can be re-used. If there is other data in the block's other pages, it must be moved to a different block, before the erase.

   A common block size is 512KiB, and a common page size is 4KiB. So if you write 4KiB of data, and that write needs to be done to a used block, that means at least 508 KiB of extra writes have to occur first; that's an inflation rate of 127x. You might be able to write 2x or 3x as fast as you can to your 10,000 rpm hard drive, but you may also end up writing 127x more data. If you are using your drive for small files, write amplification will hurt you in the long run.

   Due to the nature of flash memory's operation, data cannot be directly overwritten as it can in a hard disk drive.

   (Source: http://en.wikipedia.org/wiki/Write_amplification)

   Typical block sizes include:

   • 32 pages of 512+16 bytes each for a block size of 16 KiB
   • 64 pages of 2,048+64 bytes each for a block size of 128 KiB
   • 64 pages of 4,096+128 bytes each for a block size of 256 KiB
   • 128 pages of 4,096+128 bytes each for a block size of 512 KiB

   (Source: http://en.wikipedia.org/wiki/Flash_memory)

2. Long-Term Storage. Magnetic storage mediums often retain data longer when un-powered, so hard drives are better for long term archiving than NAND-Flash SSDs.

   When stored offline (un-powered in shelf) in long term, the magnetic medium of HDD retains data significantly longer than flash memory used in SSDs.

   (Source: http://en.wikipedia.org/wiki/Solid-state_drive)

3. Limited lifespan. A hard drive can be re-written to until the drive breaks from wear and tear, but a NAND-Flash SSD can only reuse its pages a certain number of times. The number varies, but let's say it's 5000 times: if you reuse that page one time per day it will take over 13 years to wear out the page. This is on par with a hard drive's lifespan but that's true only without factoring in write amplification. When the number is being halved or quartered it suddenly doesn't seem so big.

   MLC NAND flash is typically rated at about 5–10 k cycles for medium-capacity applications (Samsung K9G8G08U0M) and 1–3 k cycles for high-capacity applications

   (Source: http://en.wikipedia.org/wiki/Flash_memory)

4. Power Failure. NAND-Flash drives don't do well with power-failures.

   Bit corruption hit three devices; three had shorn writes; eight had serializability errors; one device lost one third of its data; and one SSD bricked.

   (Source: http://www.zdnet.com/how-ssd-power-faults-scramble-your-data-7000011979/)

5. Read Limits. You can only read data from a cell a certain number of times between erases before other cells in that block have their data damaged. To avoid this, the drive will automatically move data if the read threshold is reached. However, this contributes to write amplification. This likely won't be a problem for most home users because the read limit is very high, but for hosting websites that get high traffic it could have an impact.

   If reading continually from one cell, that cell will not fail but rather one of the surrounding cells on a subsequent read. To avoid the read disturb problem the flash controller will typically count the total number of reads to a block since the last erase

   (Source: http://en.wikipedia.org/wiki/Flash_memory)

Solution 3:

Tons of bad answers here from people that obviously only know low end SSD.

There is one reason - Price. Mostly if you do not need the performance. Once you need the IOPS budget a SSD (even in a Raid 5) gives you - anything else does not matter.

10K SAS/SATA drive: around 350 IOPS. SSD: The ones I use - last years model, enterprise - 35000

Go figure - either I need the speed, or I do not. If I do not, large discs beat everything. Cheap, good. If I need the speed, SSD's rule (and yes, SAS has advantages, but seriously guys, you can get enterprise SATA discs as easily as "look up the part number and call a distributor").

Now endurance. Those SSD I use are "mid quality". 960GB Samsun 843T's reconfigured toi 750GB the Samsung warranty covers 5 full writes per day over 5 years. That is 3500GB written every day. Before warranty runs out. Higher end models are good for 15 - 25 complete writes per day.

We move our in house virtualization platform from Velociraptor (yes, you can get them in a real 2.5" configuration if you are smart enough to look up a part number and call a distributor) with a Raid 50 of SSD and while the cost was "significantly higher" the performance went from 60MB/sec to 650. I have zero latency increase under normal load even during backups. Endurance? Again, my warranty is quite clear on that ;)

Solution 4:

Aside from cost, is there still a reason to choose a 10K RPM (or faster) hard drive over an SSD?

Isn't it obvious? Capacity. SSDs simply can't compete on capacity. If you care that much more about performance than capacity and want a single disk solution, an SSD is for you. If you prefer more capacity, you can go with a raid array of HDDs to get plenty of capacity and make up a good portion of the performance gap.