This document compares solid state drives (SSDs) and hybrid hard drives. It provides background on SSDs, noting they have no moving parts and use flash memory instead of magnetic disks. SSDs offer faster speeds but have limited storage capacity and lifetime write limits. Hybrid drives combine a small SSD cache with a standard hard disk, offering faster access to frequently used files while providing higher storage capacity at a lower cost than SSDs alone. However, hybrid drives are slower than SSDs for cached files and have shorter lifetimes if the SSD cache is managed poorly. The document concludes SSDs are best when speed is the top priority, while hybrids are suitable when both speed and capacity are important.

1. Finding Middle Ground
A comparison of solid state and
hybrid hard drives: Are hybrids really
the best of both worlds?
By: Addison Roy and Brendan Banbury

2. What makes a
SSD tick?
• An SSD (solid-state drive) is a
storage device that stores
persistent data on solid-state flash
memory.
• They are very different from
Hybrid and traditional hard drives
because they have no moving
parts at all.
• An SSD has an array of
semiconductor memory organized
as a disk drive, using integrated
circuits instead of magnetic or
optical media.
• Most SSDs use NAND based flash
technology which will retain data
without power.
• SSD manufacturers use non-
volatile NAND flash memory
because of the lower cost
compared to DRAM and the ability
to retain the data without a
constant power supply

3. Solid State Drives:
The Beginning.
• The origins of SSDs actually started in
the 1950’s . Magnetic core memory
and card capacitor read-only store
(CCROS) were called auxiliary
memory units and emerged during
the era of vacuum tube computers.
Unfortunately with the introduction
of cheaper drum storage units their
use was discontinued.
• In 1976 Dataram introduced the
world’s first solid-state drive. It
provided a massive 2 MB of storage.
• This setup, including controller board
cost $9,700.00 in 1977 which would
be approx. $36,317.00 today.
• Then in 1995 an Israeli firm M-
systems developed the template for
the flash based SSDs we are familiar
with today. Image Source: ddrdrive.com
• Storage capacity has continued to
increase while prices have decreased

4. Combining the Best of Both
Worlds: Hybrid Drives.
•In simplest terms: HDD with a
supersized adaptive cache.
•64MB cache VS 4-64GB SSD or RAM
flash memory onboard drive.
•Mostly non-volatile; RAM-based W/O
battery backup exc.
•Onboard software analyzes use
patterns.
•Commonly used programs and files
automatically or manually written to
SSD cache.
•Files replaced and added to cache as
user’s needs change.
•For standard use, performs like a SSD. Image Source: engadget.com
Disk platter only spins when cache is
full or requested data is on the disk.

5. Newer Than you Think.
•HDD and SSD came out in the 1950’s…
•Someone finally decided to combine
them in 2007.
•Hybrid innovators: Seagate and
Samsung.
•Software issues with Windows Vista
kept Hybrid drives in obscurity until
2010. (Seagate Momentus XT)
•They are still far less common than
standalone HDD or SSD.
•Still, a market niche exists, but likely
not for long.
•With SSD capacity growing and cost
plummeting, hybrids will either become Image Source: hardmac.com
obsolete, or large SSD caches in HDD
will become standard.

6. The pros.
• SSD Hybrid:
• Speed • Much faster than a HDD when the cache
– Almost instant start-up times is used effectively. Only slightly slower
– Consumer product data transfer than a SSD.
rate usually ranges from 100 MB/s • Primarily disk based storage. Much
to 600 MB/s higher capacity. Write limit for data
– Random access time is about 0.1 ms blocks not a problem for HDD portion of
because data is access directly from drive.
the flash memory • Very inexpensive compared to SSD: Cost
• No moving parts per unit of storage closer to HDD model.
– Very resistant to shock and vibration • Significantly less power consumption
than HDD. Platter only spins when
– Almost silent needed.
– Small and light weight • SSD portion can be manually managed
– Can tolerate higher temperatures with new models. New models also
than HHDs allows use on an unsupported OS.

7. The cons.
• SSD Hybrid:
• SSDs can only be erased a limited number • Un-cached memory requests are slower than
of times before it fails. Although the traditional HDD. Platter needs additional
technology has developed to manage this time to spin up.
limitation and allow the drives to last a • If management of the flash memory is poor,
number of years. the advantages of a hybrid solution are lost.
• Storage capacity is around 2 TBs but ones In addition to more time spent writing data
to the flash drive:
that size are extremely pricey
– Additional power consumption comes
• Price from frequent spin-ups of the platter,
– SSDs cost approximately US$0.65 per potentially more than a traditional HDD.
GB – A significantly reduced lifetime. Flash
• 64GB – 240 GB are reasonably priced at memory is frequently re-written (SSD have
limited writes compared to HDD). Most
$99.00 to $250.00 wear on HDD occur in spin-up and spin-
• above that prices can get extremely high down cycles. More money spent on
• OCZ 460 GB for $1,099.99 replacements.
• OCZ 960 GB for $2,599.00
• OCZ 1.2TB for 5,$399.99

8. But Which one Should you Choose?
• Solid-State Drive: Hybrid:
• When speed is the • When speed and
number one priority. capacity are both
– Smaller SSDs are important for a user
reasonably priced seeking:
– Large storage capacity is – A money-saving build.
available but can be – Miniature cases with
costly limited space.
– Money is no object – Small laptops with only
one HDD slot.

9. Sources
• http://cseweb.ucsd.edu/use • storagenewsletter.com
rs/swanson/papers/FAST20 • anandtech.com
12BleakFlash.pdf • zdnet.com
• http://technorati.com/tech • seagate.com
nology/it/article/ssd-
storage-faces-doubtful-
future/
• http://en.wikipedia.org/wiki
/Ssd
• www.memoryexpress.com
• http://www.pcworld.com/a
rticle/246617/evolution_of_
the_solid_state_drive.html
Background images from
memoryexpress.com