Question about DRBD

[macday]

Hi guys,

I just read in a thread here, that ionice(vzdump) and other features of proxmox are only working well with the cfq-scheduler.

But the drbd-wiki tell me, that drbd-devices should be set up with the deadline-scheduler and other tweaks.

What is the best-practise ?

thx
macday

 

[udo]

Hi guys,

I just read in a thread here, that ionice(vzdump) and other features of proxmox are only working well with the cfq-scheduler.

But the drbd-wiki tell me, that drbd-devices should be set up with the deadline-scheduler and other tweaks.

What is the best-practise ?

thx
macday

Hi macday,
I use DRBD with the standard pve installation without any trouble (the trouble I had before, came from the dolphin-driver... - with 10G-ethernet DRBD work rock solid).

Udo

 

[e100]

You can have CFQ globally and deadline for the DRBD related block devices.

I use sysfsutils to configure scheduler on my DRBD backing devices.

sdc and sdd are my DRBD devices

/etc/sysfs.conf:

block/sdc/queue/scheduler=deadline
block/sdc/queue/iosched/front_merges=0
block/sdc/queue/iosched/read_expire=150
block/sdc/queue/iosched/write_expire=1500
block/sdd/queue/scheduler=deadline
block/sdd/queue/iosched/front_merges=0
block/sdd/queue/iosched/read_expire=150
block/sdd/queue/iosched/write_expire=1500

I agree with Udo, 10G works great, using Infiniband cards here.

 

[macday]

I this this deadline-tweaks already and ran in some errors while vzdump-ing (concurrent local writes detected...)

I´m trying this now:

echo cfq > /sys/block/sda/queue/scheduler
echo 64 > /sys/block/sda/queue/iosched/quantum
echo 0 > /sys/block/sda/queue/iosched/slice_idle
echo 1 > /sys/block/sda/queue/iosched/group_idle
echo 512 > /sys/block/sda/queue/nr_requests

...for I got enterprise SAS RAID10 with DELL H700 HBA with writeback-cache.

I have also 10G Intel here.

 

[e100]

In over two years using DRBD on Proxmox I've never seen a "concurrent local write detected" error.

Were you running vzdump on both nodes at the same time on the same DRBD volume?