Mirror Intel Pro 1500 SSDs: 40 FSYNC to 6000 FSYNC due to sync=disabled?

Brian Puccio

Renowned Member
Jul 2, 2015
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Long Beach, NY
brianpuccio.net
I've read this thread and this thread (and a bunch of things found via google). I understand that there's a performance boost (at the expense of data security) by setting sync=disabled (as opposed to sync=standard). However, I didn't think the performance would be 144 times better. Is 40 fsyncs/second expected for Intel Pro 1500 SSDs? I'm familiar with a SSD to speed up an array of spinning platters, would a third SSD (an external ZIL) improve the performance of these two SSDs in a mirror config?

My prior experience with ZFS is a Debian wheezy install with an 8x 4TB RAIDZ2 array that I've never had performance problems with (nor felt the need to add an SSD to it to speed things up, sync=default there).

Thanks!

virty# zfs set sync=standard rpool
virty# pveperf
CPU BOGOMIPS: 38395.76
REGEX/SECOND: 363920
HD SIZE: 148.44 GB (rpool/ROOT/pve-1)
FSYNCS/SECOND:
43.62
DNS EXT: 34.62 ms
DNS INT: 28.00 ms (local)
virty# zfs set sync=
disabled rpool
virty# pveperf
CPU BOGOMIPS: 38395.76
REGEX/SECOND: 365813
HD SIZE: 148.44 GB (rpool/ROOT/pve-1)
FSYNCS/SECOND:
6194.57
DNS EXT: 30.72 ms
DNS INT: 32.81 ms (local)
virty#


virty# pveversion -v
proxmox-ve: 4.0-3 (running kernel: 3.19.8-1-pve)
pve-manager: 4.0-16 (running version: 4.0-16/a7dc5694)
pve-kernel-3.19.8-1-pve: 3.19.8-3
lvm2: 2.02.116-pve1
corosync-pve: 2.3.4-2
libqb0: 0.17.1-3
pve-cluster: 4.0-13
qemu-server: 4.0-12
pve-firmware: 1.1-5
libpve-common-perl: 4.0-8
libpve-access-control: 4.0-5
libpve-storage-perl: 4.0-11
pve-libspice-server1: 0.12.5-1
vncterm: 1.2-1
pve-qemu-kvm: 2.3-5
pve-container: 0.7-2
pve-firewall: 2.0-3
pve-ha-manager: 1.0-4
ksm-control-daemon: 1.2-1
glusterfs-client: 3.5.2-2
lxc-pve: 1.1.2-1
lxcfs: 0.9-pve1
cgmanager: 0.37-pve1
virty#
 

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