[mythtv-users] File System Recommendation?

Yeechang Lee ylee at pobox.com
Mon Apr 3 14:40:02 UTC 2006


Brian Wood <beww at beww.org> says:
> Thank you for a good explanation, now everything I have read makes
> sense, including the "bilgewater". I guess I have never noticed a
> problem because I almost never record anything longer than a 1-hour
> show, and thus never delete anything longer either.

Unless you hate movies, I'll bet that'd change with HDTV; I find
myself recording movies I've seen before just for a chance to relive
scenes over in much, much greater detail.

> I also have a lot of RAM.

RAM is irrelevant in discussing file-system write blocks, per se; it's
the limits set in ThreadedFileWriter.cpp that play a role. See
<URL:http://www.gossamer-threads.com/lists/mythtv/users/183808?search_string=tfw_def_buf_size%20yeechang;#183808>
for some previous thoughts on the subject and details on my setup.

I currently use 64, 12, and 256 as multiples, respectively; this lets
me record three HDTV streams (including at least two "high-bandwidth"
streams) and watch one at once, with no IOBOUND errors except
sometimes in the first few seconds of when the stream from my HD5000
tuner card is spooling up.

More germane to this discussion, with only one HDTV recording stream,
I can delete up to a one-hour "high-bandwidth" (about 8GB) HDTV
recording without IOBOUND messages. Adding another event (whether
another recording stream or commflagging) reduces the file size I can
safely delete significantly, but I haven't pinned down the figure yet.

Believe me, if I could use JFS (as I use on my non-MythTV RAID 5
array), I'd switch to it today; being able to delete multi-gigabyte
files in the blink of an eye is a *good thing*.
-- 
Yeechang Lee <ylee at pobox.com> | +1 650 776 7763 | San Francisco CA US


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