[OpenIndiana-discuss] ashift 13?

[Jason Matthews]

On 4/7/2015 2:36 PM, Jason Matthews wrote:
>
> The results are in. 4k sectors consume 302G for this data set.
>
> 512b  202GB
> 4KB    302GB
> 8KB    474GB


It seems that George Wilsons modification to the sd driver to let you 
nail the sector size only works in one direction. You can only specify a 
sector size larger than the advertisement from the disk. In other words, 
if the disk is advertising 4k sectors you can specify 8k sectors but not 
512 bytes.

This still leaves me with the problem of having 200 512byte DC S3700s 
and 100 4k DC S3700s. I have to either run them at 4k and loose half of 
the expensive SSD storage or flash them all to 512 bytes which really sucks.

I still dont understand why we lose so much storage using sector sizes 
larger than 512 bytes. I need to verify this but the fall out seems to 
come from compression. I accidently sent a file system over w/o lz4 
enabled and it consumed 602GB the same number that mbuffer said it sent. 
That tells me that the on disk storage is working as advertised but some 
how compression is falling apart larger sector sizes.

Are there inefficiencies that creep into LZ4 with larger block sizes 
some how?