On Thu, Nov 26, 2015 at 2:19 AM, krad <kra...@gmail.com> wrote: > true, but in my experience usb pen drives are variable in terms of > performance across different sticks and different areas of the same stick. > This can complicate things a little, and is often not worth the effort. You > obviously run the ssd over usb though, and I still do on one server I run > as I haven't been able to sort the down time yet. >
Nowadays, USB 3.x-based sticks in USB 3.x ports should be fast enough that they'll be helpful. You won't get the full 5 Gbps from one (unless you spend as much or more than an SSD), but it will be much better than the measly 0.5 Gbps of a USB 2.x stick/port. Don't bother trying with a USB 2.x stick, or with anything plugged into a USB 2.x port. Invariably, it will just slow things down. I used to use 8 GB USB2 sticks in USB2 ports for L2ARC (with a separate one for the root filesystem). When I had 4x IDE disks in a raidz1 vdev, they helped. When I migrated to 4x SATA1 disks in a raidz1 vdev, they helped. When I migrated to 4x SATA3 disks in dual-mirror vdevs (with root-on-ZFS), suddenly the USB stick became the bottleneck. Removing it actually made the whole system faster (better throughput, more IOps, lower latency, smoother system overall). As always, YMMV, and test it with your own setup. :) -- Freddie Cash fjwc...@gmail.com _______________________________________________ freebsd-stable@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-stable To unsubscribe, send any mail to "freebsd-stable-unsubscr...@freebsd.org"