ZFS

[Gary Corcoran]

Sam wrote:

> On Thu, 16 Sep 2004, Gary Corcoran wrote:
> 
>> Sam wrote:
>>
>>> On Thu, 16 Sep 2004, Jan Grant wrote:
>>>
>>>> On Thu, 16 Sep 2004, Sam wrote:
>>>>
>>>>> Let's suppose you generate an exabyte of storage per year.  Filling 
>>>>> a 64-bit
>>>>> filesystem would take you approximately 8 million years.
>>>>
>>>>
>>>>
>>>> Hang on, I'm not sure I know where these numbers are coming from.
>>>>
>>>> 1PB is - what? 2^50 bytes? That looks closer to 2^64 than your
>>>> figures indicate. I'd imagine an exabyte a year ought to be topping out
>>>> after 16 years. I'm missing about half-a-dozen orders of magnitude
>>>> somewhere it seems.
>>>
>>>
>>>
>>> 1PB is indeed 2^50 bytes, but filesystems don't address on the byte,
>>> but on the block (1K, 4K, 8k, ...).  The numbers I'm using assume
>>> the filesystem addresses on the sector, which is unrealistically
>>> small.  Jack it up to a 16K blocksize and you jump a few hundred
>>> ZB in size.
>>
>>
>> You have to be able to *seek* on a byte boundary.  Hence doesn't a
>> "64-bit" filesystem indeed mean "only" 2^64 bytes?
> 
> 
> Only for the file you're seeking on.

Yeah, okay, there's multiple definitions of what "64-bit filesystem"
is referring to.  So what are FreeBSD's current filesystem limitations?
2^64 bytes files, and 2^64 blocks per filesystem?  But I seem to recall
some problems as people were approaching a terabyte or two ???

Gary