[mythtv-users] Conventional Wisdom Watch

Yeechang Lee ylee at pobox.com
Thu Jan 19 00:55:18 UTC 2006

John Biundo <johnbiundo at sbcglobal.net> says:
> Interesting post.  How might the LVM2 performance hit manifest
> itself? Could it be the source of some strangeness I'm seeing with
> pre-buffering pauses?

I can't speak to your particular situation. All I know is that my
local read and write speeds on an eight-spindle,
JFS-on-LVM2-on-(single) software RAID 5 went up by several multiples
when I made the sole change of removing LVM2 from the equation. I have
previously noted here that none of the several large-scale academic
RAID arrays that most resemble my setup uses LVM2.

> Also related to your filesystem comments: might jfs NOT be a great
> choice for the ringbuffer?  I've got it on its own jfs partition
> now. 10GB.  Should I consider switching that to reiserfs or xfs?

I based my comment on what several comparative benchmarks I've read
reported regarding XFS versus JFS (all of them also noting that the
differences weren't that great) and the feeling that I should say
*something* negative about JFS. On the other hand, when I removed LVM2
on my array as mentioned above I did briefly try XFS, only to find
that bonnie++ reported speeds about two thirds that of JFS's, so I
reverted to what I knew best.

I was quite serious about ReiserFS; in my experience it is definitely
the filesystem people love to hate as much as love. XFS and JFS get
plaudits from pretty much everyone who uses them, albeit with the
occasional caveat that they as of yet do not have *on Linux* the
real-life performance lifetimes that ext2 and ext3 do.

Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US

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