Date: Mon, 20 Oct 2008 22:19:33 -0700 From: Carl <k0802647@telus.net> To: freebsd-questions@freebsd.org Subject: gjournal: journaled slices vs. journaled partitions Message-ID: <48FD6665.5000102@telus.net>
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My goal is to build a 2-disk server configured with gmirror and gjournal for maximum reliability. There will never be a second operating system on the system, but I prefer not to freak out any non-FreeBSD repair tools that might be used, so I will use compatibility instead of dangerously dedicated mode. This means I need one slice, but see no reason for more. Inside that one slice will be the usual array of partitions (ie. /, swap, /var, /tmp, /usr, /data). Now, I think gmirror allows me to mirror the entire drive rather than forcing me to do per-slice or even per-partition mirroring. I'm looking for the simplest in-field replacement procedure when one of the drives dies and I imagine a whole drive mirror achieves this. Am I right? gjournal, OTOH, has me really confused. The man page for gjournal(8) specifically does not recommend that small partitions be journaled. I assume that's because the journal provider rivals the partition in size and is therefore overhead heavy. It seems to me, though, that if I can journal the slice as a whole instead of per-partition journaling, that there will essentially then be only one journal provider for the combination of all partitions (ie. slice) and that the aforementioned overhead becomes minor. Having smaller partitions included in journaling seems like a good thing to me. So how do I achieve per-slice journaling instead of per-partition? Every time I read up on someone else's gjournal implementation, it seems to end with adding <partition>.journal entries to /etc/fstab. Am I trying to achieve the impossible or ill-advised here? Carl / K0802647
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