From what I read at the link below, the write journal mirrors the contents of the stripe cache. This suggests that the write journal cannot contain more uncommitted data than the stripe cache can hold. Is that correct?
https://www.kernel.org/doc/Documentation/md/raid5-cache.txt
So, if the stripe cache size is 1GB then is there any advantage in making the journal device larger than 1GB? I assume no, but I'm also wondering about journal overhead.
My understanding is that the stripe cache size is limited to 32768 and that the total memory size is the size value x 4096 x num disks. IOW, max 128MB per disk (32k x 4k x 1). Is that correct?
--Larkin