Date: Sat, 11 Sep 2010 10:47:03 -0500 From: Adam Vande More <amvandemore@gmail.com> To: RW <rwmaillists@googlemail.com> Cc: freebsd-questions@freebsd.org Subject: Re: gjournal+geli Message-ID: <AANLkTimczgt4a0j4oW9hMJ5LjGD%2BJR=Aa7KZbJDrck6g@mail.gmail.com> In-Reply-To: <20100911152558.27153c31@gumby.homeunix.com> References: <20100911152558.27153c31@gumby.homeunix.com>
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On Sat, Sep 11, 2010 at 9:25 AM, RW <rwmaillists@googlemail.com> wrote: > > I'm planning to use gjournal+geli on a 2TB drive in a USB enclosure. > > What I've read about this suggest that the order should be: > geli-gjournal-ufs. I was wondering if it's possible to do it in > the order gjournal-geli-ufs, which should be much more efficient. I've > read that ufs should go directly on gjournal, but I just wanted to > check that that is needed. > > I was also wondering about the journal size, and whether there are any > performance optimizations to be made to mitigate the extra > encryption/decryption in the journal. The man page suggests a size of at > least 2xmemory which would be 2x1.5GB now, or maybe 2x16GB to allow for > potential upgrades. It seems very large. The disk will hold fairly > static data so it will be mostly be long sustained writes as files are > copied in. Currently coping from geli to geli with soft-updates is > slightly cpu limited. > AFAIK, ufs must be on top of gjournal. Specific changes were made to allow ufs to be aware of the journal and I think sticking geli in-between would destroy that relationship. IME, gjournal is more sensitive to load as the man page also suggests. I have one production server with moderate load, and a 5 GB problem. I think something like 5 -10 GB journal would be more than enough for almost all loads, but that's just a guess. It's easy to test though, just run blogbench or some other io benchmark for a sustained period of time. If it doesn't panic, you're golden. -- Adam Vande More
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