Reducing system dataset write frequency

[scott_sch]

I've set up an old server to run Freenas 11.1-U7 from mirrored usb drives for the purpose of trying out BSD and ZFS.

I'm using two pools, one for system files(freenas-boot) and one for playing with NFS storage, jails, etc.
I appreciate clean divisions in my system and having this ".system" dataset on my storage pool violates everything I hold sacred.

From the forums and documentation I've read so far, it seems possible to move .system to the freenas-boot pool but the frequent writes will abuse my boot drives. Is there any way to reduce the write frequency through settings within freenas? Or would there be any obvious danger in placing it on ram disk and have cron replicate the data at intervals.

Thanks in advance for your consideration

 

[Chris Moore]

I appreciate clean divisions in my system and having this ".system" dataset on my storage pool violates everything I hold sacred.

Sacred? Really? It is easy to move the system dataset somewhere else. Recommend NOT using USB boot media because they tend to fail relatively quickly. We used to suggest that YEARS ago but for a long time now we have been suggesting a SMALL (low capacity) old SSD. A 20GB model will be bigger than you need, but I am using a 40GB model because it was the smallest I could buy at the time. With the endurance of an SSD, you can put the system dataset on the boot pool. With the system dataset on the boot pool, the activity on the boot pool will look like this:

That amount of activity will kill a USB memory stick quickly (couple months) but a SSD handles it without any trouble.
Look here for how to move the system dataset. It is right in the GUI:
https://www.ixsystems.com/documentation/freenas/11.2-U5/system.html#system-dataset

 

[Chris Moore]

Is there any way to reduce the write frequency through settings within freenas?

No. It is updating logs and keeping other needed records for the system.

Or would there be any obvious danger in placing it on ram disk and have cron replicate the data at intervals.

Obviously, you want all system RAM dedicated to caching storage pool activity, not this record-keeping and if the system crashed, the data in RAM would be lost.

 

[Chris Moore]

Why are you so worried about reducing the activity the storage pool?

 

[scott_sch]

i dont mind storage pool activity in the storage pool, its the system files in the storage pool that i'd like to find a new home for. I'd like to remove them to the freenas-boot pool, but I've read that due to the constant writes, it's not an ideal solution. If I'm forced to choose between evils I'd rather trash my boot mirror. I'd be willing to applying a few Mb of ram to reducing write frequency and if you have any suggestions I would certainly appreciate them.

 

[Chris Moore]

if you have any suggestions I would certainly appreciate them.

I already did. Use a mirror of mechanical drives for the boot pool if you don't want to dedicate SSDs to the task. It doesn't need to be fast, it just needs endurance. Move the system dataset and logging to the boot pool. Done. Modifying the system by force with some RAM disk configuration is just asking for it to break. Don't do that.

 

[scott_sch]

I appretiate you taking the time, but if the system performs at all decently, then the logs write to null for all I care. If there is some critical thing thats being frequently written then I'm totally ignorant of it and would be completely satisfied with your suggestion if you could please name it.

 

[Chris Moore]

if the system performs at all decently, then the logs write to null for all I care.

Is your system performing poorly? Please detail your hardware per the forum rules:
https://www.ixsystems.com/community/threads/forum-guidelines.45124
If you have bad performance, it is more likely due to improper configuration than because of the activity of of the system dataset and system logs.

 

[scott_sch]

My system is performing pretty well and the software is great, otherwise I would post version and hardware details as per the forum rules. My only concern is the logical arrangement of my system. I'm pretty sure I'll get over it. ;)

 

[scott_sch]

Your first reply just appeared and I see what you meant by having already offered suggestions. I have no idea what happened there. Thanks Chris