Neil Bothwick <n...@digimed.co.uk> wrote: > On Tue, 9 Feb 2016 21:42:05 +0100, waben...@gmail.com wrote: > > > > For SSD must set special option in kernel config? > > > > No. > > > > But you should insert the "discard" option into /etc/fstab. > > Otherwise you have to use fstrim from time to time. > > The use of discard is discouraged in many places, because it can > impact performance. Running fstrim weekly from cron, at a time things > are quiet, is generally preferred.
This depends on the SSD. On my old SSD (Corsair with sandforce controller) discard slowed down write performance significantly. On my new SSDs (Samsung 850 Pro) I don't notice a performance impact. But you are right. With a cronjob he will be on the safe side regardless what kind of SSD is inside his laptop. But a one week interval could IMHO maybe too long. I think trimming the SSD every day (maybe on shutdown) would be a better idea. With my old SSD I first used the discard option in fstab. But after some days I noticed that write performance was not much better then with a conventional hardisk. So I wrote a script that trimmed the SSD on every shutdown with fstrim. This process was very slow, about 20 Minutes or so. With the 850 Pro, fstrim needs only some seconds to trim the disk, even when it trims the entire free space. Before I've used the discard option with my 850 Pro SSDs, I run fstrim manually before my weekly backups. I noticed that always the complete free space was trimmed. So I decided to run fstrim manually every day for some time. I experienced, that even then some GB of the free space were trimmed, on some days even all. This depended on how much data was written on my daily update procedure. If there were none or only some small compilations during the update then the trimmed amount of data was about some GB, but when some bigger programs were updated then nearly all of the free space was trimmed. After some days I give the discard option a try. As I couldn't notice a performance impact I decided to stay with it. -- Regards wabe
