Re: SSD TBW

On 21/08/2026 00:22, Lawrence D’Oliveiro wrote:
> On Thu, 20 Aug 2026 16:55:09 +0100, mm0fmf wrote:
> 
>> On 20/08/2026 05:42, Lawrence D’Oliveiro wrote:
>>>
>>> So why not divide the TBW by the actual capacity of the drive? Then
>>> you end up with a ratio of how much can be written in total, to the
>>> drive capacity -- call it, say, the “cumulative write ratio”.
>>>
>>> That number, it seems to me, correlates better to the overall quality
>>> of the unit than TBW does.
>>
>> When I compare my NVME drive endurance for a 2TB device, it is quoted as
>> being 1200TBW and the 1TB version is quoted as 600TBW.
> 
> There you go -- both drives have a cumulative write ratio of 600.
> 
>> I was a little concerned whether 1200TBW would be enough considering
>> how much "chatter" there was on the drive. After 1 year of use, the
>> drive has seen 4TBW meaning it will last me 299 more years. I think
>> that will be enough.
> 
> Trouble is, we don’t know what the shape of the failure curve is like.
> To take an extreme case, if the shape is skewed enough so that 99% of
> drives fail with a write ratio within, say, 10 (i.e. your drive fails
> within 5 years), while 1% last as long as 60000 rewrites, the
> arithmetic mean would still stay the same, but you would be rather
> more likely to suffer data loss ...

It's warranted for 5 years. I think it will outlast the warranty period 
and I'd be probably be considering a replacement by then.