Replacing Drive with SSD

krad kraduk at
Wed Sep 16 08:18:45 UTC 2015

a bit late to this i know but when I have under over provisioned, I did it
by getting the drives to report a lower amount of storage than they have
rather than using the non partitioned way of doing it. This guarantees the
drives firmware knows it free space much more effectively than the
partition method which doesnt mean a lot to the drive. I used something
like the below just after doing a secure erase on the drive to reduce the
reported size from say 120GB to 100GB (this was done from the gparted
livecd, as i couldnt find out howto do it within BSD back then)

hdparm -Np281323627 --yes-i-know-what-i-am-doing /dev/sdb

On 10 September 2015 at 18:42, Paul Kraus <paul at> wrote:

> On Sep 10, 2015, at 11:00, Brandon J. Wandersee <
> brandon.wandersee at> wrote:
> > Leaving blocks unpartitioned doesn't mean those blocks won't be written
> > to; it just ensures that a certain amount of space (and so a certain
> > number of blocks/cells) must always be free, forcing writes to be spread
> > across different physical portions of the disk in a relatively even
> > manner. It's my understanding that this over-provisioning isn't
> > exactly necessary in most SSDs nowadays. It just serves as a stronger
> > guarantee than entrusting everything to a drive's firmware.
> Each SSD model has some amount of over provisioning built in. The more
> expensive, Enterprise grade SSDs have more (in many cases much more) than
> the cheaper consumer units. So based on the performance you need and the
> SSD you have, it is still prudent to manually over provision with
> unpartitioned space.
> Note that some vendors will tell you about their over provisioning and
> others don’t.
> --
> Paul Kraus
> paul at
> _______________________________________________
> freebsd-questions at mailing list
> To unsubscribe, send any mail to "
> freebsd-questions-unsubscribe at"

More information about the freebsd-questions mailing list