SSD card = camera memory or maybe a USB stick
One thing I've heard about flash memory is that it is VERY slow compared
to a hard drive.
That would make wonder if it's viable for any large amount of storage.
Sp
SD cards are generally in cameras, standing for Secure Digital, they use
flash with a uC or specialized ASIC on the card to handle commands.
USB sticks are generally called USB sticks or flash sticks, not "SSD USB
sticks." They also use a uC on the PCB to handle commands.
Although these are technically SSDs in the strictest sense of the meaning
"Solid State Drive." When someone refers to SSDs, they tend to refer to
drives that have an ATA/SAS/PCI-E interface and use SLC/MLC NAND Flash for
storage, or in some cases RAM (enterprise solutions, and the rare consumer
one like the Gigabyte drive using DDR from a few years ago).
For consumer MLC NAND based SSDs, Flash memory is very slow to erase
compared to a hard drive, which can just copy over data. SSDs have to zero
out a large block of Flash and read-modify-write. Write throughput depends
on the configuration of the flash, and how good the SSD controller is. For
example, my Intel X25Vs run 5 channels of flash, write at 40MB/s max
throughput, and read at 190MB/s. The X25M runs 10 channels of flash, and
writes twice as fast with roughly the same read speed. You can think of
flash channels like RAID0, or ganged dual channel RAM.
Write speed doesn't matter much in this application.. although SandForce
based SSDs read AND write at 285MB/s.. and most any drive has more
sequential write throughput than the Intel drives. While MLC consumer drives
are still "fairly," new, the flash in most of the drives is better than what
you'd find in an SD card. They are rated at a UBE of 10^14, same as a SATA
hard drive. SAS drives are 10^15 UBE.
SLC should last longer than MLC even with primarily reads.
-Frank
_______________________________________________
Mid-Hudson Valley Linux Users Group http://mhvlug.org
http://mhvlug.org/cgi-bin/mailman/listinfo/mhvlug
Upcoming Meetings (6pm - 8pm) MHVLS Auditorium
Oct 6 - Creating Browser Extensions for Firefox and Chrome
Nov 3 - Open Source Hardware: Bugs, Beagles and Beyond
Dec 1 - IBM's Open Client Deployment
