Mailing List Archive: MythTV: Mythtvnz

Re: mythtvnz Digest, Vol 21, Issue 38

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sam at samborambo

May 13, 2009, 2:01 PM

Post #1 of 8 (1464 views)
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Re: mythtvnz Digest, Vol 21, Issue 38

>>I would suggest using a 16Gb or 32Gb Compact Flash card with an IDE
> adapter.
>>Saves gluing it all together.
>
> Although... thinking about it more.
> 25watts running 24 hours a day is about $54 of power a year.
> That means you have to spend less than $54 to get a payback within one
> year.
> More than a year and SSD's will probably have doubled in capacity and
> halved in price.
>
It would really be the saving of 12W from the single 250GB Seagate spinning
all the time as the system drive so that equates to only $27 annual savings
- so I'm not really saving many trees. 4x 8GB USB flash sticks could be
delivered for $130 all up. The cheapest 32GB solid state drives are just
over $200 but the main problem is my 6 SATA ports are quite valuable.
Having a rethink, a pair of 16GB CF cards in a CF to IDE adaptor would give
me 40MB/s in RAID for about $180.

I think that solid state storage should increase stability in Live TV a
lot. I still get the odd freeze up from mythtv expiring stuff between shows
while watching - even with slow deletes turned on, XFS for a file system
and a big array. Having storage with an access time in the microseconds
should solve that.

> I would tend to hold on and spend that $54 on the power to maintain your
> status quo and wait till solid state drives come down a bit more in price
> and expand in size.
>
Flash memory has started to plateau, just like hard drives did a couple of
years ago. It used to be that I'd buy only the storage that I currently
needed but since bulk storage has stayed around the $0.20/GB for so long,
it makes sense to buy for other reasons like RAID structure, etc. Also,
with the global economic down turn, I don't think solid state storage is
going to be cheap in the near future.

> Then you can replace all your hard disks with SSD's, spend a lot less
> money, get more capacity and also reduce your power bill from that point
> forward.
>
Are you saying I should replace my 2TB array with solid state "next year"?
Solid state drives are currently 27 times the price of spinning drives. How
much do you predict this $10,000 solid state array will drop in the next
year? :)

> $54 does not buy a lot of hardware right now that is going to really give
> you the capacity you are likely to need over the next 2 to 3 years and
you
> will probably find yourself running out of space and needing to spend
more
> money than what you will save in power over that period of time.
>
> Toby
>

Sam.

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steven at openmedia

May 13, 2009, 4:17 PM

Post #2 of 8 (1377 views)
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Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

On Thu, May 14, 2009 9:01 am, Sam Hadley-Jones wrote:
>>>I would suggest using a 16Gb or 32Gb Compact Flash card with an IDE
>> adapter.
>>>Saves gluing it all together.
>>
>> Although... thinking about it more.
>> 25watts running 24 hours a day is about $54 of power a year.
>> That means you have to spend less than $54 to get a payback within one
>> year.
>> More than a year and SSD's will probably have doubled in capacity and
>> halved in price.
>>
> It would really be the saving of 12W from the single 250GB Seagate
> spinning
> all the time as the system drive so that equates to only $27 annual
> savings
> - so I'm not really saving many trees. 4x 8GB USB flash sticks could be
> delivered for $130 all up. The cheapest 32GB solid state drives are just
> over $200 but the main problem is my 6 SATA ports are quite valuable.
> Having a rethink, a pair of 16GB CF cards in a CF to IDE adaptor would
> give
> me 40MB/s in RAID for about $180.
>
> I think that solid state storage should increase stability in Live TV a
> lot. I still get the odd freeze up from mythtv expiring stuff between
> shows
> while watching - even with slow deletes turned on, XFS for a file system
> and a big array. Having storage with an access time in the microseconds
> should solve that.

I'm really surprised at your freeze up issues. I'm using ext3 and slow
deletes and no longer have any playback issues.

Did you have a chance to run some performance tests on the raid5 array
like I suggested as i'm wondering if you have other issues.

--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email - steven [at] openmedia
website - http://www.openmedia.co.nz

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mythtvnz at hotblack

May 13, 2009, 5:33 PM

Post #3 of 8 (1385 views)
Permalink

Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

On 14/5/09 9:01 AM, Sam Hadley-Jones wrote:
>>> I would suggest using a 16Gb or 32Gb Compact Flash card with an IDE
>> adapter.
>>> Saves gluing it all together.
>> Although... thinking about it more.
>> 25watts running 24 hours a day is about $54 of power a year.
>> That means you have to spend less than $54 to get a payback within one
>> year.
>> More than a year and SSD's will probably have doubled in capacity and
>> halved in price.
>>
> It would really be the saving of 12W from the single 250GB Seagate spinning
> all the time as the system drive so that equates to only $27 annual savings
> - so I'm not really saving many trees. 4x 8GB USB flash sticks could be
> delivered for $130 all up. The cheapest 32GB solid state drives are just
> over $200 but the main problem is my 6 SATA ports are quite valuable.
> Having a rethink, a pair of 16GB CF cards in a CF to IDE adaptor would give
> me 40MB/s in RAID for about $180.
>
> I think that solid state storage should increase stability in Live TV a
> lot. I still get the odd freeze up from mythtv expiring stuff between shows
> while watching - even with slow deletes turned on, XFS for a file system
> and a big array. Having storage with an access time in the microseconds
> should solve that.
>

4 x USB is asking for trouble for a boot or mysql drive. If just 1 of
those 4 has an issue you could waste a lot of time trying to recover
data, etc.

Flash devices still have limited life spans for writes. If you're intent
on wasting some of those writes with LiveTV, then at least put it on
it's own flash device, and not on one that is also used for boot/mysql.

- Wade

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Aaron.Drysdale at provencocadmus

May 13, 2009, 10:12 PM

Post #4 of 8 (1376 views)
Permalink

Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

As I'm new to Mythtv, I'm wondering what these "slow deletes" are that
have been mentioned a few times now. Is this something I need to turn
on, or is on by default now? What sort of issues can crop up, that I
should be aware of? Ie, how would I recognize if I have a problem
requiring this?

Cheers
Aaron
-----Original Message-----
From: mythtvnz-bounces [at] lists
[mailto:mythtvnz-bounces [at] lists] On Behalf Of Steven Ellis
Sent: Thursday, 14 May 2009 11:17
To: MythTV in NZ
Subject: Re: [mythtvnz] mythtvnz Digest, Vol 21, Issue 38

On Thu, May 14, 2009 9:01 am, Sam Hadley-Jones wrote:
>>>I would suggest using a 16Gb or 32Gb Compact Flash card with an IDE
>> adapter.
>>>Saves gluing it all together.
>>
>> Although... thinking about it more.
>> 25watts running 24 hours a day is about $54 of power a year.
>> That means you have to spend less than $54 to get a payback within
one
>> year.
>> More than a year and SSD's will probably have doubled in capacity and
>> halved in price.
>>
> It would really be the saving of 12W from the single 250GB Seagate
> spinning
> all the time as the system drive so that equates to only $27 annual
> savings
> - so I'm not really saving many trees. 4x 8GB USB flash sticks could
be
> delivered for $130 all up. The cheapest 32GB solid state drives are
just
> over $200 but the main problem is my 6 SATA ports are quite valuable.
> Having a rethink, a pair of 16GB CF cards in a CF to IDE adaptor would
> give
> me 40MB/s in RAID for about $180.
>
> I think that solid state storage should increase stability in Live TV
a
> lot. I still get the odd freeze up from mythtv expiring stuff between
> shows
> while watching - even with slow deletes turned on, XFS for a file
system
> and a big array. Having storage with an access time in the
microseconds
> should solve that.

I'm really surprised at your freeze up issues. I'm using ext3 and slow
deletes and no longer have any playback issues.

Did you have a chance to run some performance tests on the raid5 array
like I suggested as i'm wondering if you have other issues.

--------------------------------------------
Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email - steven [at] openmedia
website - http://www.openmedia.co.nz

_______________________________________________
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mythtvnz [at] lists
http://lists.ourshack.com/mailman/listinfo/mythtvnz
Archives http://www.gossamer-threads.com/lists/mythtv/mythtvnz/

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jfp at clearfield

May 13, 2009, 10:59 PM

Post #5 of 8 (1366 views)
Permalink

Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

> As I'm new to Mythtv, I'm wondering what these "slow deletes" are that
> have been mentioned a few times now. Is this something I need to turn
> on, or is on by default now? What sort of issues can crop up, that I
> should be aware of? Ie, how would I recognize if I have a problem
> requiring this?

It's not to fix a problem, but a GUI improvement.

If you're using the ext3 filesystem, it's notoriously slow deleting files, so
that setting just queues up the delete so that the GUI is still useable in
the meantime.

--
------------------------------------------------------------------------
Jean-Francois Pirus <jfp [at] clearfield> Technical Manager
Phone (+64-9) 358 2081 Clearfield Software Ltd
Fax (+64-9) 358 2083 1st Floor 8-10 Whitaker Place
Mob (+64-21) 640 779 P O Box 3901 Auckland, New Zealand
------------------------------------------------------------------------

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Aaron.Drysdale at provencocadmus

May 13, 2009, 11:09 PM

Post #6 of 8 (1368 views)
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Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

>It's not to fix a problem, but a GUI improvement.
>
>If you're using the ext3 filesystem, it's notoriously slow deleting
files, so
>that setting just queues up the delete so that the GUI is still useable
in
>the meantime.

OK, thanks. I've experienced no problems deleting large files from the
frontend, so I assume it's already implemented in my 0.21 version.

Aaron

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mythtvnz at hotblack

May 13, 2009, 11:11 PM

Post #7 of 8 (1373 views)
Permalink

Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

On 14/5/09 5:59 PM, Jean-Francois Pirus wrote:
>> As I'm new to Mythtv, I'm wondering what these "slow deletes" are that
>> have been mentioned a few times now. Is this something I need to turn
>> on, or is on by default now? What sort of issues can crop up, that I
>> should be aware of? Ie, how would I recognize if I have a problem
>> requiring this?
>
> It's not to fix a problem, but a GUI improvement.
>
> If you're using the ext3 filesystem, it's notoriously slow deleting files, so
> that setting just queues up the delete so that the GUI is still useable in
> the meantime.
>

I thought it was a new method (introduced 0.20) that deleted a file in
chunks (by progressively shrinking a file), and was designed not to hog
I/O on filesystems like ext3. Didn't know it had anything do with with
GUI responsiveness.

- Wade

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nick.rout at gmail

May 14, 2009, 1:11 AM

Post #8 of 8 (1362 views)
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Re: mythtvnz Digest, Vol 21, Issue 38 [In reply to]

On Thu, May 14, 2009 at 6:11 PM, Wade Maxfield <mythtvnz [at] hotblack> wrote:
> On 14/5/09 5:59 PM, Jean-Francois Pirus wrote:
>>> As I'm new to Mythtv, I'm wondering what these "slow deletes" are that
>>> have been mentioned a few times now. Is this something I need to turn
>>> on, or is on by default now? What sort of issues can crop up, that I
>>> should be aware of? Ie, how would I recognize if I have a problem
>>> requiring this?
>>
>> It's not to fix a problem, but a GUI improvement.
>>
>> If you're using the ext3 filesystem, it's notoriously slow deleting files, so
>> that setting just queues up the delete so that the GUI is still useable in
>> the meantime.
>>
>
> I thought it was a new method (introduced 0.20) that deleted a file in
> chunks (by progressively shrinking a file), and was designed not to hog
> I/O on filesystems like ext3. �Didn't know it had anything do with with
> GUI responsiveness.
>

well its more system responsiveness but it shows up mainly in the gui
being unresponsive (you probably don't notice if daemons take a little
longer to complete, say, delivering an email)

I noticed my last mythbuntu install made (at last) a separate /var/lib
partition as xfs, and xfs has no such problems so that may account for
Aaron's lack of a problem. Or a decent motherboard, or good luck, or
the moon being in aquarius or whatever...

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