On 07/27/2011 03:06 PM, Lutz Vieweg wrote:
I don't think mdadm knows whether its constituent devices are SSDs.
In block/cfq-iosched.c I see a test that looks like this:
if (blk_queue_nonrot(cfqd->queue) && cfqd->hw_tag)
return;
I just verified that indeed, /sys/block/sd*/queue/rotational contains
0 for SSDs and 1 for magnetic disks.
One catch, though, seems to be that this attribute seems not to be
propagated through additional block device layers, so e.g.
a loop-device based on a SSD is, strangely, tagged as being "rotational",
as is a device-mapper based on the SSD.
So you can detect SSDs if given as underlying devices directly, only.
Regards,
Lutz Vieweg
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