On Fri, Aug 13, 2010 at 05:14:22PM +0400, Andrey Panin wrote:

On 224, 08 12, 2010 at 05:29:37PM -0500, bchociej@gmail.com wrote:

quoted

From: Ben Chociej <redacted>

Modified mkfs.btrfs to add hot data relocation option (-h) which
preallocates BTRFS_BLOCK_GROUP_DATA_SSD and
BTRFS_BLOCK_GROUP_METADATA_SSD at mkfs time for future use by hot data
relocation code.  Also added a userspace function to detect whether a
block device is an SSD by reading the sysfs block queue rotational flag.

IMHO this policy is too inflexible. What if I have large array of slow SATA 
disks and some fast SAS ones ?

  I'm hoping that this is just first cut, and future versions will have options.
For now, it is totally unusable without a way of using mirrored SSD for
hot data.
  Ideally, hot storage devices should be online selectable and changeable.

-- 
Tomasz Torcz                                                       72->|   80->|
xmpp: zdzichubg@chrome.pl                                          72->|   80->|