On Fri, Mar 14, 2014 at 12:07:54PM +0000, Duncan wrote: > Marc MERLIN posted on Thu, 13 Mar 2014 22:17:50 -0700 as excerpted: > > > On Thu, Mar 13, 2014 at 09:39:02PM -0600, Chris Murphy wrote: > >> > >> On Mar 13, 2014, at 8:11 PM, Marc MERLIN <m...@merlins.org> wrote: > >> > >> > On Sun, Mar 09, 2014 at 11:33:50AM +0000, Hugo Mills wrote: > >> >> discard is, except on the very latest hardware, a synchronous > >> >> command (it's a limitation of the SATA standard), and therefore > >> >> results in very very poor performance. > >> > > >> > Interesting. How do I know if a given SSD will hang on discard? > >> > Is a Samsung EVO 840 1TB SSD latest hardware enough, or not? :) > >> > >> smartctl -a or -x will tell you what SATA revision is in place. The > >> queued trim support is in SATA Rev 3.1. I'm not certain if this > >> requires only the drive to support that revision level, or both > >> controller and drive. > > > > I'm not sure I'm seeing this, which field is that? > > > ATA Version is: 8 > > ATA Standard is: ATA-8-ACS revision 4c > > Your drive didn't report it, but here, I have SATA fields as well, in > addition to the ATA fields: > > Here's the fields from my Corsair Neutron SSDs: > > ATA Version is: ATA8-ACS (minor revision not indicated) > SATA Version is: SATA 2.5, 6.0 Gb/s > > Here's the fields from my Seagate 500-gig 2.5-inch spinning rust: > > ATA Version is: ATA8-ACS T13/1699-D revision 4 > SATA Version is: SATA 2.6, 3.0 Gb/s
Ok, my smartmontools was too old. I got a newer one and now have proper output: Device Model: Samsung SSD 840 EVO 1TB Serial Number: S1D9NEAD934600N LU WWN Device Id: 5 002538 85009a8ff Firmware Version: EXT0BB0Q User Capacity: 1,000,204,886,016 bytes [1.00 TB] Sector Size: 512 bytes logical/physical Rotation Rate: Solid State Device Device is: Not in smartctl database [for details use: -P showall] ATA Version is: ACS-2, ATA8-ACS T13/1699-D revision 4c SATA Version is: SATA 3.1, 6.0 Gb/s (current: 6.0 Gb/s) Local Time is: Fri Mar 14 10:49:39 2014 PDT SMART support is: Available - device has SMART capability. SMART support is: Enabled So I have Sata 3.1, that's great news, it means I can keep using discard without worrying about performance and hangs Thanks, Marc -- "A mouse is a device used to point at the xterm you want to type in" - A.S.R. Microsoft is to operating systems .... .... what McDonalds is to gourmet cooking Home page: http://marc.merlins.org/ -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html