Date: Mon, 31 Aug 2015 15:23:53 +0100 From: RW <rwmaillists@googlemail.com> To: freebsd-questions@freebsd.org Subject: Re: Replacing Drive with SSD Message-ID: <20150831152353.5ca78976@gumby.homeunix.com> In-Reply-To: <55E45973.2050103@sneakertech.com> References: <CEAD84AD-341A-4FB9-A3A1-D0D5A550AFFD@lafn.org> <alpine.BSF.2.20.1508281235390.74312@wonkity.com> <20150829220311.c7608be1.freebsd@edvax.de> <alpine.BSF.2.20.1508300633160.44682@wonkity.com> <55E45973.2050103@sneakertech.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Mon, 31 Aug 2015 09:41:07 -0400 Quartz wrote: > > Making a partition for free space is one way. Another way is to > > leave part of the drive unpartitioned. Either one just guarantees > > there is a good supply of unused blocks available to the drive. > > I'm not super well versed on exactly how SSD TRIM works. How does the > drive in question know which blocks are or aren't free, isn't that a > function of the filesystem? For that matter, how does the drive even > "know" which parts are or aren't partitioned, it's not like they're > programmed to understand MBR vs GPT, etc. Physical blocks are assigned to logical sectors on write. Partitioning a device and putting UFS on it doesn't write into the free space on a filesystem or any unpartitioned space. > How does the system > communicate to the drive firmware layer which blocks are in use? When a file is deleted, the OS can use TRIM to tell the device which sectors not longer contain data.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20150831152353.5ca78976>