[ale] SWAP over NFS

[JK]

Brian Pitts wrote:
> JK wrote:
>> laytonjb at charter.net wrote:
>>
>> Isn't there a rather low physical limit on the total possible number of 
>> read/write cycles
>> for a particular flash chip?  It seems like swapping on flash would hit 
>> that limit pretty fast.
> 
> I think the limit runs from 100,000 to 1,000,000 depending on the card. 
> Since the cards do wear-leveling, one form of insurance should be to get 
> a larger card than you need. A 2GB 266x (40 MB/s) CompactFlash card 
> costs less than $30.

I didn't know the cards did wear-leveling on their own; that's
a nice feature (and makes me wonder if some schemes I've seen
implementing explicit wear-leveling on the OS side are gonna
end up shooting themselves in the foot by interacting badly
with the card's on-board wear-leveling mechanism). But in any
case, when wear limits are hit, one would start seeing random
mysterious errors due to corruption of the swap device, with no
apparent cause.  This seems to me a Very Bad Thing. 'Course,
same thing can happen with bad HD sectors, but my impression is
that this situation could occur much more rapidly with flash,
especially if (as in the scenario in this thread) the whole reason
for adding the flash device is that you expect the system to
swap its ass off all the time.  I mean, 1,000,000 is really
a pretty small number.

-- JK

-- 
I do not particularly want to go where the money is -
  it usually does not smell nice there. -- A. Stepanov