Sandisk states the writes per sector endurance of it 2GB card at 100,000 writes. I will have to eat some crow on the endurance of the new SSD drives though! Intel claims its X25-E SSD (SLC) at 1 Petabyte writes or 58 days of 17 TB random writes. I doubt any of us will ever reach that under several years even with a virtual file enabled. Of course you should remember that "Intel" drive is an Enterprise level SSD. The one we can afford probably will not be as robust, but will certainly live longer, with a virtual file enabled, than several hours. Things do change over a year or so. SLC memory lasts 10 times as long as MLC so you should take that into account if you propose to run virtual memory enabled. So if you can afford a SSD you could very well use it as virtual memory, but a HDD is going to be cheaper. and considering the performance level of the USB interface an SSD is way overkill. As to a SD Card it will last a while but will die in the end and not to far in the future.
copied from wikipedia:
Memory wear Another limitation is that flash memory has a finite number of program-erase cycles (typically written as P/E cycles). Most commercially available flash products are guaranteed to withstand around 100,000 P/E cycles, before the wear begins to deteriorate the integrity of the storage. Micron Technology and Sun Microsystems announced an SLC flash memory chip rated for 1,000,000 P/E cycles on December 17, 2008.
The guaranteed cycle count may apply only to block zero (as is the case with TSOP NAND devices), or to all blocks (as in NOR). This effect is partially offset in some chip firmware or file system drivers by counting the writes and dynamically remapping blocks in order to spread write operations between sectors; this technique is called wear leveling. Another approach is to perform write verification and remapping to spare sectors in case of write failure, a technique called Bad Block Management (BBM). For portable consumer devices, these wearout management techniques typically extend the life of the flash memory beyond the life of the device itself, and some data loss may be acceptable in these applications. For high reliability data storage, however, it is not advisable to use flash memory that would have to go through a large number of programming cycles. This limitation is meaningless for 'read-only' applications such as thin clients and routers, which are only programmed once or at most a few times during their lifetimes.
hopefully that will clarify the life of flash memory. But I still had to eat some crow!
512MB version 2.0 as WordPress Server
Motorola Lapdock with Pi2B
Modded Rev 1.0 with pin headers at USB
(RS)Allied ships old stock to reward its Customers for long wait!