slow sata drives with default 4.3

[karlos]

I get that Proxmox is setup for enterprise but it works great for a home lab. Where slower drives are common...

3.2 all default settings with sata 7200 drives
Old desktop pc - FSYNCS of around 1200
I/O is ok

4.3 all default settings with sata 7200 drives
VMware on Windows PC - FSYNCS around 900
I/O is ok
Old desktop pc - FSYNCS < 100
I/O is aweful

So what has changed in 4.3 that the default install makes such a difference on this older hardware...
With my limited knowledge I found if I add barrier=0 too /etc/fstab:

/dev/pve/root / ext4 errors=remount-ro,barrier=0 0 1

buffered reads and fsyncs are as expected again.

Is this the correct method to fix I/O here?

 

[dietmar]

We switched from ext3 to ext4, and now use barrier=1 by default.

 

[karlos]

barrier=1 by default

the default PVE5 install shows "/dev/pve/root / ext4 errors=remount-ro 0 1"

I then add barrier=1 "/dev/pve/root / ext4 errors=remount-ro,barrier=1 0 1"

Both ways on ssd and hdd fsyncs shows < 100

I change it too barrier=0 and fysncs >1000

Running barrier=0 isnt always a good option but the alternative slow IO on ext4 isnt viable
Perhaps going back to ext3 on VM drives is a better option?

Why is it when I install on Vmware under Win 10 on the same hardware without adding barrier=0 is the performance better than the install on real hardware (around 800 fysncs)

can someone make sence of that?

 

[dietmar]

Running barrier=0 isnt always a good option but the alternative slow IO on ext4 isnt viable
Perhaps going back to ext3 on VM drives is a better option?

No, that would not help. Newer kernels fixed many fs bugs, and that comes with performance costs. For example, old ext3 installation simply used barrier=0 as default, so that was the reason why it was faster.