How to safely upgrade the kernel module

Writeboost releases new version in months or weeks. New release typically includes improvements, fixing or enhancements. Basically, I recommend users to always upgrade to the latest version. We can upgrade the installed version safely because Writeboost is just a caching module.

The safest and recommended way to upgrade Writeboost is:

1. Write back all dirty cache blocks to the backing store.
2. Unmap caching. (dmsetup remove)
3. Zero out the first sector of the caching device to reformat it.
4. Upgrade Writeboost.
5. Reboot.
6. Reconstruct Writeboost'd device.

If you are stick to this upgrade procedure, you are completely free from unnoticed lack of compatibility.

Another benefit of this upgrade procedure is you can avoid taking much time on log-replay because you reformat the caching device, which is executed at reconstruction time.

Dmitry Smirnov's management tool (https://gitlab.com/onlyjob/writeboost) implements this best-practice procedure.