SAS drives Background Medium scans - how to enable?

[SMnasMAN]

Im aware this may be a bit redundant with the way ZFS works (as well as scrubs), however i would still like to know if this is possible to enable, as i do think its something worth enabling/running, even under ZFS.

In addition to smart short/long/conv. tests, most SAS drives, internally, have a background medium scan that can be enabled. (espesically as i have mostly SAS SSD enterprise drives in freenas)

I know i can pull drives, put them in ubuntu, enable background medium scans via sdparm, and put them back into Freenas, But is anyone aware of a tool to enable this while drives attached to Freenas, ie via FN cli?

ie is there an equivalent sdparm tool on FN? (or maybe sg_tools command to enable this?)

I came across this as i was logging the (smartctl -x /dev/daXX > out.txt) for some new HGST SAS SSD drives i had just attached to FN, and noticed that they all had background medium scans , in progress, running in the background - so i began investing this a bit more as none of my existing SAS SSD drives, in freenas, had this enabled.
(the new drives were pulled from a prior machines HW raid card, thus im assuming the raid cards "patrol read" or similar task had enabled this on the ssds)

more info here:

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(examples of this running/enabled, and not - both drives are on my FN box - i removed alot of the smart output to better highlight the Background scan results section):

Enabled/Running:

Code:

root@freenas:~/trash # smartctl -x /dev/da58
smartctl 6.6 2017-11-05 r4594 [FreeBSD 11.2-STABLE amd64] (local build)
Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor:               HITACHI
Product:              HUSML404 CLAR400
Revision:             C337
Compliance:           SPC-4
User Capacity:        400,000,000,000 bytes [400 GB]
Logical block size:   512 bytes
Physical block size:  4096 bytes
Rotation Rate:        Solid State Device
Transport protocol:   SAS (SPL-3)
.......

Background scan results log
  Status: scan is active
    Accumulated power on time, hours:minutes 26927:50 [1615670 minutes]
    Number of background scans performed: 176,  scan progress: 95.83%
    Number of background medium scans performed: 176

DISABLED:

Code:

root@freenas:~/trash # smartctl -x /dev/da6
smartctl 6.6 2017-11-05 r4594 [FreeBSD 11.2-STABLE amd64] (local build)
Copyright (C) 2002-17, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Vendor:               HGST
Product:              HSCP0480S5xnNMRI
Revision:             3P02
Compliance:           SPC-4
User Capacity:        480,999,997,440 bytes [480 GB]
Logical block size:   512 bytes
Physical block size:  4096 bytes
LU is resource provisioned, LBPRZ=1
Rotation Rate:        Solid State Device
Transport protocol:   SAS (SPL-3)
......

Background scan results log
  Status: no scans active
    Accumulated power on time, hours:minutes 37112:01 [2226721 minutes]
    Number of background scans performed: 0,  scan progress: 0.00%
    Number of background medium scans performed: 0

 

[JoeAtWork]

Hi SMnasMan,

Why would you want to enable this?

Now you have something that is trying to waste power and potentially slow down a disk write that could cause unbalanced filling of your vdevs. It can also slow down a dis read. Dell has to have this "background patrol read" on perc cards because it is too hard to have the controller do this heavy lifting since it has a very small brain.

With TrueNAS we want the scrub and long smart tests to be run frequently to detect issues before a failure. Even then I have power down TN Filers and had seagate drives not spin up. :-(

Thanks,
Joe