[mythtv-users] "TFW, Error: Write() -- IOBOUND" 8 minutes long!

[Douglas Peale]

On 03/17/2011 06:36 AM, Kevin Kuphal wrote:
> On Wed, Mar 16, 2011 at 11:56 PM, Douglas Peale
> <Douglas_Peale at comcast.net>wrote:
>
>> I have been having picture breakups in my recordings lately. Looking in my
>> backend logs I noticed that they seemed to correlate
>> to "TFW, Error:Write() -- IOBOUND" errors. Most of them are short, on the
>> order of seconds, but this one:
>>
>> 2011-02-21 22:56:51.280 TFW, Error: Write() -- IOBOUND begin
>> remaining(4865) free(0) size(4194304) cnt(1)
>> 2011-02-21 22:57:00.738 Player(0): Timed out waiting for free video
>> buffers.
>> 2011-02-21 23:05:02.603 TFW, Error: Write() -- IOBOUND end
>>
>> is over 8 minutes long, and corresponded with the missing ending of a
>> recording.
>>
>> The system is an i7 processor with 6 GB of ram and a 1.5 TB SATA drive. The
>> only slightly unusual thing I am doing on my system
>> is starting the commercial flagging as soon as the recording starts. The
>> assumption being this should reduce disk accesses since
>> the data should still be in the disk cache when the commercial flagger
>> tries to read it.
>>
>> I assume the normal behavior would be worse since it would start commercial
>> flagging the moment the recording ended, the
>> recording would be bigger than the disk cache, so the beginning of the file
>> would already have been dumped from the cache, and
>> if a second recording had started, the second recording would be fighting
>> with the commercial flagger for disk bandwidth.
>>
>> Am I making a bad assumption here? Should I just go out and get a SSD for
>> the system, and use the existing drive only for
>> recordings?
>>
>> Is there any way to get MythTV to buffer to RAM when the disk drive gets
>> bottlenecked? 6GB of ram should be good enough for a 30
>> minute ring buffer.
>>
> I had no end of problems when I had the OS, swap, database, and recordings
> all on the same spindle.  SATA is not the best for heavier random access
> loads and I found that having recordings separate from OS/database was good
> enough but having the DB on it's own disk also was best (3 devices).
>
> Kevin
>
>
>
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This might be ideal for a OS drive:
http://www.techpowerup.com/140917/Super-Talent-Intros-CoreStore-Line-of-PCI-Express-SSDs.html

This claims it is "available now":
http://www.youtube.com/gosupertalent
But I can't seem to find a price for it anywhere.
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