Minimal cache device size information

Open-CAS / open-cas-linux

Open CAS Linux

https://open-cas.com

BSD 3-Clause "New" or "Revised" License

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Minimal cache device size information #1069

Open Deixx opened 2 years ago

Deixx commented 2 years ago

Description

There is no info about the lowest device size that allows for starting a cache on that device. In particular the error for too small device also doesn't provide that information (or any information that size is the problem) - it just says Device does not meet requirements., which is a bit enigmatic. I think the info should be placed on the website, in the aforementioned error message and maybe in man?

Reason

Users need to know the minimal size of a cache device.

kmajzero commented 2 years ago

Kernel dmesg output after trying to start cache on a 1M device: [ 275.971533] Inserting cache cache1 [ 275.972115] cache1: Metadata initialized [ 275.972416] cache1: Successfully added [ 275.972417] cache1: Cache mode : wt [...] [ 275.973978] cache1: Cache device size must be at least 40 MiB [ 275.974213] cache1: Attaching cache device failed [...]