hideo wrote:
Hi everyone,

I was replacing a disk in a gmirror+geli pair and decided to compare
the performance of gmirror+geli+gjournal before adding the new disk.

When using these three together is the appropriate order to 1) fdisk
and label 2) mirror the disk, 3) geli the partitions, and 4) use the
geli partitions for gjournal label?

It depends on what you want to do. To minimize administration overhead I'd modify the sequence like this: gmirror the drives, geli the entire gmirror, then fdisk it, then add gjournal, use UFS labels. Of course, you can never boot from such a thing.

With respect to performance, I find the writes to the gjournal disk
about half as fast, which I expected from the benchmarks I've seen.
However, reading a single file is identical between the two:

        dd if=/sofupdates/1.mpg of=/dev/null bs=1m
        994049168 bytes transferred in 34.858793 secs (28516454 bytes/sec)

        dd if=/gjournal/1.mpg of=/dev/null bs=1m
        994049168 bytes transferred in 34.335267 secs (28951258 bytes/sec)

Is this expected? I was under the impression that reads should be
somewhat faster with gjournal.  Is geli decryption the limiting
factor here?

No, performance with gjournal can at most be as fast as without gjournal (in reality it will always be infinitesimally slower since there's another layer in GEOM added).

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