Perhaps irrelevant, but a colleague of mine recently solved a puzzling performance issue merely by replacing the existing SATA cables with new, properly-rated cables. Turns out, much like USB v1 vs USB v2, there's next to nothing distinguishing SATA I cables vs SATA II cables vs SATA III cables, except for unusually poor performance when used at too high a speed. Only the magnitude of your performance drop suggests this; also the fact that you get good raw read performance, which mirrors the symptoms in the SATA cable case precisely. -Adam
On April 24, 2016 11:49:38 AM CDT, Robert Fantini <[email protected]> wrote: >if those are not ssd drives, then adding a zil drive will most likely >help. > >On Sat, Apr 23, 2016 at 2:15 PM, Ralf <[email protected]> >wrote: > >> Hi, >> >> I encounter very bad read/write performance on my mirror-zfs, even on >> hypervisor-side. >> >> After shutting down all VMs, reading and writing from raw ZFS block >> devices VMs runs at maximum 5MiB/s (tested with dd >> if=/dev/rpool/VM/disk-100 of=/dev/null) while reading from the >> underlying raw-disk (/dev/sda) has good performance (~100MiB/s). Of >> course, performance inside VMs is even worse. Any ideas? >> >> This is my setup: >> Proxmox / 4.1-30/9e199213 / Linux 4.4.6-1-pve / ZFS mirror, two disks >> >> ZFS setup: >> >> $ dmesg | grep ZFS >> [ 2.882118] ZFS: Loaded module v0.6.5.6-1, ZFS pool version 5000, >ZFS >> filesystem version 5 >> >> $ zpool status >> [snip] >> NAME STATE READ WRITE CKSUM >> rpool ONLINE 0 0 0 >> mirror-0 ONLINE 0 0 0 >> sdb2 ONLINE 0 0 0 >> sda2 ONLINE 0 0 0 >> >> ZFS module parameters: >> $ cat /etc/modprobe/zfs.conf >> options zfs zfs_arc_max=3221225472 >> >> Partition alignement: >> $ parted /dev/sda >> (parted) align-check o 2 >> 2 aligned >> >> Dedup: off >> Checksumming: on >> Compression: off >> >> Anything helps! >> >> Cheers >> Ralf >> _______________________________________________ >> pve-user mailing list >> [email protected] >> http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user >> >_______________________________________________ >pve-user mailing list >[email protected] >http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ pve-user mailing list [email protected] http://pve.proxmox.com/cgi-bin/mailman/listinfo/pve-user
