🚀 go-pugleaf

On Aug 12, 2:41 pm, Paul <nos...@needed.com> wrote:
> Penang wrote:
> > Please pardon me if this topic has been discussed before, but as far
> > as I know about the Flash memory, they have a relatively low limit on
> > re-write, as compared to hard disk
>
> > In situation where database use in concern, read and write operation
> > takes place very often
>
> > I know that there are pros and cons in this issue, but basically my
> > question is this --- How reliable is SSD?
>
> http://www.imation.com/PageFiles/83/SSD-Reliability-Lifetime-White-Pa...
>
> The last page of the report addresses "wearout" as a function of writes.
> As far as I can tell, they use the best kinds of writes (large sequential),
> to make the estimate.
>
> The flash block size is 128KB. If you want to update 4KB of that,
> you have to rewrite the whole thing. So relatively speaking, it is
> "32x" more expensive, to deal with the small sized write.
>
> To understand whether SSD may be of value to you, you need to know
> how much data you write per day. If it is a small amount, then it may
> not matter what size the writes are. If you write large amounts of
> data, then you'd want to understand the characteristics very well.
> (That means sorting all the writes into "size bins".)
>
> Before you buy anything, you should also read some recent reviews
> of SSD products, and some of the performance problems they can have.
> Don't just buy the SSD with the lowest price. You're regret it.
> This is a hint as to what you're looking for. There are more articles
> around, which test for this.
>
> http://www.anandtech.com/cpuchipsets/intel/showdoc.aspx?i=3403&p=8
>
> If you want to build a test system for evaluation, use Intel
> X25-E SSDs.


One funny thing is --- Intel has just announced the suspension of
their X25-E SSD product

Reason? Technical

But rumors of pre-mature deaths of the SSD may cause Intel to think
twice about selling products that don't work


>
> *******
>
> None of the above addresses "reliability" as such. The above addresses
> "wearout", where you know the thing will eventually fail, as a function
> of how many writes you've done. Wear leveling makes the most of the
> write cycle limits of SLC or MLC flash chips.
>
> Reliability takes into account other things, like how often a
> flash chip just rolls over and dies for no particularly good reason.
> Take the stick of RAM in my previous computer as an example - one entire
> chip stopped responding, after about two years of usage. Why did that happen ?
> That is an example of something not accounted for as wearout -
> that is a device failure unrelated to usage. RAM should not
> wear out. And yet I've had failures at the two year mark (the
> stick was not abused, and the computer case is cooled well).
> If the chips in a flash drive do that too, then not only would
> I have wearout to consider, I'd have device reliability
> (chips dying) to add to the effect. And the only way to study that
> in any effective way, is to get field return data for SSD drives.
> And nobody gives out field return data.
>
>     Paul