On 24/03/17 21:09, James Harris wrote:
> On 22/03/2017 19:55, druck wrote:
>> On 21/03/2017 23:43, James Harris wrote:
>>> On 21/03/2017 23:17, druck wrote:
>>>> On 21/03/2017 23:12, James Harris wrote:
>>>>> True. Sorry to druck for not reading his/her post properly. An SSD
>>>>> might
>>>>> be an option for some applications. But I think I would rather have
>>>>> multiple raid-1 USB sticks - if I can find some that don't compete
>>>>> with
>>>>> the stove.
>>>>
>>>> A RAID of memory sticks will be far more likely to suffer failures than
>>>> one good quality SSD.
>>>
>>> Nevertheless, if one of three raid-1 memory sticks failed it could be
>>> hot-replaced and the array would continue uninterrupted. (Two would be
>>> enough but three would be safer.)
>>
>> The failure mode of flash is such that it becomes unreliable before
>> failing completely. If you aren't lucky you'd end up with 3 degrading
>> sticks all containing slightly different contents, and unsure what data
>> is good and what isn't.
>
> That's the first I have heard of flash failure modes. From a quick
> read-up it seems that writes start to fail. Presumably they are only a
> problem if they go undetected. So don't flash drivers read back what
> they have written?
>
>
I am not certain of the following, but I think teh answer is not with
pen drives and sticks, but possibly with SSDS they do some form of error
checking

With an SSD what you specify in terms of tracks and sectors bears no
relation to where the data is actually stored. There's a CPU sorting
stuff out and a table of logical to physical maps that are changed to do
the wear levelling and several different algos of that in play too.

--
Religion is regarded by the common people as true, by the wise as
foolish, and by the rulers as useful.

(Seneca the Younger, 65 AD)

--- SoupGate-Win32 v1.05