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Keith Nash
2017-03-15 23:33:11 -05:00
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@@ -26,3 +26,13 @@ Copies the FreeNAS system configuration file to a dataset you specify. The backu
__boomer-FreeNAS-9.10.2-U2-e1497f2-20170315224905.db__
Edit this script and specify the target dataset where you want the backup files copied.
# set_hdd_erc.sh
Sets the Error Recovery Control (aka SCTERC or TLER) read and write values on your system's hard drives. What is this? There is a good discussion in the ["Checking for TLER, ERC, etc. support on a drive"](https://forums.freenas.org/index.php?threads/checking-for-tler-erc-etc-support-on-a-drive.27126/) thread on the FreeNAS forum, and you can find more gory details in [this FAQ](https://www.smartmontools.org/wiki/FAQ#WhatiserrorrecoverycontrolERCandwhyitisimportanttoenableitfortheSATAdisksinRAID) at the [smartmontools.org](https://www.smartmontools.org) website. This key quote from the FAQ sums up why you want to set this up on your FreeNAS servers:
>"It is best for ERC to be "enabled" when in a RAID array to prevent the recovery time from a disk read or write error from exceeding the RAID implementation's timeout threshold. If a drive times out, the hard disk will need to be manually re-added to the array, requiring a re-build and re-synchronization of the hard disk. Limiting the drives recovery timeout helps for improved error handling in the hardware or software RAID environments."
By default, the script sets both the read and write timeout value to 7 seconds. You can change either or both of these values to better suit your environment.
Some hard drives retain these values when powered down, but some do not - including the HGST 7K4000 drives I use in one of my systems. For this reason, I configure my FreeNAS servers to run as a post-init startup script.