Implement a(n almost) RAID 1 system from a batch file.
v1.0 [2020-01-04]
Usage:
simRaid1.cmd <source_dir>\ <destination_dir>\ [-f]
simRaid1 allows you to sorta implement a RAID 1 system from a batch file. It's not exactly realtime,
but it's close enough for many use cases. It essentially uses robocopy to mirror one folder/drive/whatever to another.
It runs the robocopy command in an infinite loop, which checks to see what files have been modified in the source and then only re-writes/modifies those in the destination.
It comes in handy when setting up RAID from Disk Management isn't an option (for example, if you're dealing with USB drives), or if you just want to mirror two folders.
The -f flag speeds operations up (fast mode), making the script run closer to realtime, but this means that you won't be shown the ETA, junction points will be excluded and that the number of retries in case of failures and wait times between failures are reduced.
In default mode, the script will retry thrice if it can't read a file, waiting for 3 seconds between each try.
In fast mode, the script will retry once if it can't read a file, after a 1 second wait.
You can, of course, change these values in the script.
Note that all filesystem reads take place from the source directory, the destination directory simply contains an up-to-date copy. Filesystem read/write speeds are not impacted.
This script is inferior to regular RAID 1 in many ways, except:
- It works with (sub-)folders, not just drives.
- It allows you to first decrypt an encrypted drive and then start the mirroring process, which is something that cannot be done with
Disk Management's mirror functionality. - If the drive you're mirroring to is slower than the main drive (for eg, backing up to an HDD from an SSD), write speeds on the main drive are not affected by the write speeds of the slower drive.
- It works with USB/external drives, unlike
Disk Management - Mirroring can be turned on/off instantly
- No complicated setup required