gjournal: journaled slices vs. journaled partitions

[Carl]

Laszlo Nagy wrote:
>> So how do I achieve per-slice journaling instead of per-partition?
> The docs only says this: "gjournal only supports UFS2". It does not 
> specifically say that you cannot have per-slice journaling. However, 
> since you could have other filesystems on your slice, I bet that slice 
> based journaling is not supported.

I thought I read somewhere that because gjournal is block based and not 
really part of the filesystem, that it could easily be extended for any 
other filesystem. My imagination said that gjournal was probably 
therefore only temporarily limited to a slice full of UFS partitions. 
Anyone know for sure?

> Another tricky question: why would you journal a SWAP partition?

Well, I don't really want to, but how big does a partition like /var 
have to be before it's no longer ill-advised to journal it individually? 
A fair bit of writing can occur in /var and the scenario my server will 
occupy has me concerned about inglorious shutdowns.

What are the actual reasons for why journaling a small partition is 
considered a bad idea?

Carl                                             / K0802647