Continuous writes on ZFS pool

[Frosch1482]

Hi,

i have set up my new Freenas and by creating one ZFS pool with 4 x WD Red drives.
From "Reporting" feature in the Web-Gui, I noticed, that the drives continuous write with a speed of 50K... (ok this is not much, but there is no client connected, nothing... The Freenas is totally idle...)

Where does this come from? From syslog and plugins?

The box is a home NAS. It can happen that for days there is no one accessing the files stored on the NAS. I just want that the 4 drives do nothing if there is nothing to do. Eventually in can put the Syslog and plugins to another driver (new ZFS pool) just to avoid that 4 drives are running instead of 1 or 2.

Any idea what is causing this continuous writes?

Thx
Frosch

 

[joeschmuck]

Simple answer is yes, syslog by default, and definitely plugins can cause disk access.

As for the WD Red drives running all the time, mine have been running full time since day one, no issues at all but maybe I got lucky. The only concern with WD Red drives is if your head loading counter is going up like crazy (LCC). Some of the WD Red drives had an 8 second head parking timer which is too short in my opinion and should be either 300 seconds or disabled. Originally the WD Reds came with the timers set to disabled, then they set them to 8 seconds. Now I think some are coming out set to 300 seconds. WD can't make up their minds. Read this thread if you're interested in this issue.

 

[cyberjock]

syslog will do some writes.. plugins and jails may, that depends on what you are running.

 

[Frosch1482]

I leared the LLC issue by hard since i f***ed up 4 wd green drives... :) the red once are fine in terms of llc... I checked it several times if the counter goes up :)

I thought spinning the drives down could save some electricity... As i said before sometimes the nas is not used for days...

I still have a 64gb ssd drive which could be perfect for syslog and jails (transmission & my-sql for xmbc) and one of the wd green drives for downloads...

If i can remove the continuouse write access from the 4 wd reds i guess i could spin them down... Or am i wrong?

 

[cyberjock]

Sounds like its all correct to me.

Keep in mind that scrubs and smart testing will wake up the drive. SMART testing should be at a regular interval and since we don't recommend spindown on disks because the act of spinup/spindown puts more wear and tear on drives and shortens their life, I'm not sure how much of a favor you are doing yourself.

Me, I let them spin 24x7. If I'm going out of town for a week and I know I won't use the server while i'm gone I'll shut it down. But that's it.

 

[Frosch1482]

I could keep them running as well... I think it is just better to move plugins from the 4 drives to a single drive... I do not see any reason why 4 drives should read and write just because of a simple my-sql database and a stupid transmission client running :)

Do you see any topics with the continuous write accesses on an ssd drive?

 

[cyberjock]

I know a few people have moved their jails to an SSD on purpose. But not to deliberately spin down disks.

 

[indy]

I use a crappy old ssd just for jails and syslog.
Even though it is not reflected in the smart-stats I believe (!) this constant access would shorten the disks life time.
Also Freenas seems to like having an unencrypted pool available at startup.

 

[joeschmuck]

Think of this as well, with respect to moving the jails to a separate drive... if you have a drive failure of the "jails" drive then all your jails are possibly gone. If you leave your jails on the main drives and you are running a RAIDZ1 lets say, well you can have a single drive fail and you still have your jails in tact. It's just something to consider.

 

[indy]

I use the SSD with copies=2 to defend against bit flips.
But you are right, if the SSD fail as a whole the jails are gone.
Not a big loss in my case though.