Average writes to Disk

fireodo

@johnpoz

For my system I took these settings (considering also jimps opinion)

zfs set sync=disabled zroot/tmp (pfSense/tmp on new 2.5.2 install)
zfs set sync=standard zroot/var (pfSense/var)

and fine tuning: vfs.zfs.txg.timeout=120

I hope to get a balance between security and the write intensity to disk. I will report in the next 24 hours.

Thank you all for your Patience and help!
fireodo

stephenw10

@johnpoz said in Average writes to Disk:

edit: @stephenw10 that looks interesting.. Must be something new for 21.09, I do not see any sort of graph available in 21.05.1... Or is that something outside of pfsense, like vm host where you have pfsense running?

Yeah, sorry, that's a VM in Proxmox. Waaaay easier to see the actual disk use there IMO.

Steve

johnpoz

@stephenw10 said in Average writes to Disk:

Yeah, sorry, that's a VM in Proxmox.

For a second there - thought we were getting some new information graphs ;) In light of this discussion, such info in the monitor graphs would be slick.. Especially if could show total amount of data written lifetime, etc.

fireodo

As I promised:

after 24 hours the main system (with the settings above) reduced the writings from about 20GB/day to about 1,8GB/day :-)
edit1: after another 24h the writes have settled at 0,89 GB/day ;-)

edit2: after about 2 weeks the writes come to a middle of 0,70GB/day (for those who are interested)

johnpoz

That is a signification change to be sure..

How much does UFS write?

fireodo

@bmeeks said in Average writes to Disk:

This may be a classic case of you can't "have your cake and eat it, too" ... .

You're right, its always a balance and taking the decision goes hand in in hand with support the consequences :-)

fireodo

@johnpoz said in Average writes to Disk:

That is a signification change to be sure..

Indeed.

How much does UFS write?

I have no unit with UFS so I cannot say. The unit I had setup with UFS is in the meantime on ZFS. But I remember the writings where much lower ...

johnpoz

Well my question is then - if your going to drastically reduce the sync to disk which is one of the advantages of zfs.

Until such time that some of the other things are available for easy use, like snapshots and say rollback of updates that zfs could bring to the table.

If your concerned about the amount of writes because of ssd or emmc, wouldn't it make more sense to just use ufs?

fireodo

@johnpoz said in Average writes to Disk:

If your concerned about the amount of writes because of ssd or emmc, wouldn't it make more sense to just use ufs?

Thats indeed an argument. But ... even with those "adjustments" ZFS is still much more robust and those disabled syncs (/tmp /var) are not compromising the consistency of the FS pool (zroot resp. pfSense). (I read that in a documentation about ZFS) (https://docs.oracle.com/cd/E26217_01/E35769/html/performance-storage.html)
BTW. This are tweaks for me and my environment - a pfsense in a enterprise environment I would leave untouched in this matter.

jacol

@tomashk Thanks for this, on my pfsense 2.7.2 I used this commands

on CLI
zfs set sync=disabled pfSense
System -> Advanced -> System Tunables - set vfs.zfs.txg.timeout to 180

dropped from 28% IO delay to 5 %