[Nottingham] RAID stripe size?

[Martin]

Summary for the 'executive view' :-)

On 29 September 2011 12:01, Martin <martin at ml1.co.uk> wrote:
[---]
> An interest here is that all new HDDs as of January this year are
> manufactured with the new 4kByte physical sectors rather than the old
> 512Byte sectors. They transparently maintain 512Byte sector
> compatibility by performing a read-modify-writes as needed, but at a
> high performance cost...
>
> See:
> http://en.wikipedia.org/wiki/Advanced_format

[---]

> Trying to guess some real world numbers:
>
> Hence as a guess... For HDDs depending on application, chunks of
> 64kByte to 256kByte;
>
> For SSDs I'd guess go right down to the write page size of 4kBytes.
>
> Note that for SSDs, the 4kByte read/write performance is usually given
> as /the/ headline (best) spec. Also, for performance charts I've seen,
> SSDs max out on their read/write data rate at about the 1kByte IO
> read/write size in any case.
>
>
> And then... For btrfs for SSDs, that suggests formatting with:
>
> mkfs.btrfs -L SSD_label_name -s 4096 /dev/sdX
>
> or for 16kByte write pages:
>
> mkfs.btrfs -L SSD_label_name -s 16384 /dev/sdX
>
> (And btrfs can implement it's own "RAID" at the filesystem level)

Thoughts?

Cheers,
Martin