Seagate Archive HDD

[Allan Jude]

On 2015-03-26 23:38, Xin Li wrote:
> 
> 
> On 3/26/15 17:58, Adrian Chadd wrote:
>> ... all the talk about this stuff, and yet noone's talked about
>> how ZFS is supposed to be append only, and boy wouldn't that be
>> awesome. :)
> 
> It doesn't overwrite existing data with the assumption that a, let's
> say, 4K-native drive doesn't have a 1MB "band" when writing.
> 
> I hope the "journal" would be helpful for this assuming it is on
> non-volatile medium...
> 
> Cheers,
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> 

Also, ZFS does write to the vdev label (256kb each, 2x at the front and
2x at the end of the drive) frequently (every transaction group, so at a
minimum, every 5 seconds by default). The vdev label has a ring of
uberblocks, that then point to the most recent metadata. If there was
some special place on disk these could be located to avoid being part of
a large band, and avoid the write amplification, that would likely make
a big difference.

-- 
Allan Jude

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