Mailing List Archive: MythTV: Users

SSD for speed up FE/BE

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josu.lazkano at gmail

Jun 6, 2012, 2:52 PM

Post #1 of 8 (743 views)
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SSD for speed up FE/BE

Hello all,

I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
FE/BE system. Actually I host MySQL data directory on 2.5 HDD
(5400rpm) EXT4 disk. I have some questions about SSD setup.

1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
Mount options?
2. Must I host other files on the SSD disk? channel icons? logs?

I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
any help, thanks and best regards.

--
Josu Lazkano
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pc-mythtv08a at crowcastle

Jun 6, 2012, 3:15 PM

Post #2 of 8 (723 views)
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Re: SSD for speed up FE/BE [In reply to]

On 06/06/12 17:52, Josu Lazkano wrote:
> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>
> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
> Mount options?

An SSD file system must support TRIM or performance will be sub-par, so
EXT3 is out. EXT4 is a fine choice.

> 2. Must I host other files on the SSD disk? channel icons? logs?
>
> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
> any help, thanks and best regards.

That's tiny, but I understand the cost factor. I put in one that holds
everything except the media files, and I was surprised at how little
difference it seemed to make. Some things are slower now, as the media
drive spins down when it didn't before with the whole OS on the drive.
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pjrobinson at metronet

Jun 6, 2012, 4:43 PM

Post #3 of 8 (718 views)
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Re: SSD for speed up FE/BE [In reply to]

On 06/06/12 23:15, Preston Crow wrote:
> On 06/06/12 17:52, Josu Lazkano wrote:
>> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
>> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
>> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>>
>> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
>> Mount options?
>
> An SSD file system must support TRIM or performance will be sub-par,
> so EXT3 is out. EXT4 is a fine choice.
>
>> 2. Must I host other files on the SSD disk? channel icons? logs?
>>
>> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
>> any help, thanks and best regards.
>
> That's tiny, but I understand the cost factor. I put in one that
> holds everything except the media files, and I was surprised at how
> little difference it seemed to make. Some things are slower now, as
> the media drive spins down when it didn't before with the whole OS on
> the drive.
My Nvidia ION2 Atom 525 mythtv 11.10 setup uses 2x1TB HDDs as a RAID 1
for media (/var/lib/mythtv) and 1x60GB SSD for everything else. I can't
say I notice any difference in performance (it just works, recording
and playback of HD TV) but it is a lot quieter and cooler than just
using HDDs. I've run a non-ION2 mythtv 8.10 system using a 30GB SSD and
and single 500GB HDD for media for several years now without issue.
With the cost of SSDs falling almost daily 4 or 8GB seems too small, I'd
suggest 30GB as a minimum.

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warpme at o2

Jun 6, 2012, 11:55 PM

Post #4 of 8 (719 views)
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Re: SSD for speed up FE/BE [In reply to]

On 6/6/12 11:52 PM, Josu Lazkano wrote:
> Hello all,
>
> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>
> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
> Mount options?
> 2. Must I host other files on the SSD disk? channel icons? logs?
>
> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
> any help, thanks and best regards.
>
> --
> Josu Lazkano
> _______________________________________________
> mythtv-users mailing list
> mythtv-users [at] mythtv
> http://www.mythtv.org/mailman/listinfo/mythtv-users
>
Josu,
Sometime ago I was experimenting little with SDD in my MythTV system
(mythtv backend).
Result were surprising enough that I decide to recall them them here.

My BE is 880G based mobo with AMD235E CPU, 4G RAM, and base storage on
2x2TB WD green.
First HDD is OS+DB and hosts HD movies.
Second HDD is /myth volume.
OS is ArchLinux derivative.

All FE are based on ATOM1 and are disk-less PXE booted.
OS is minimyth derivative.

MythTV on tests was v0.25pre-4055-gf9f8b71-dirty-20120111

In my SSD tests I replaced OS+DB drive to SSD (Samsung 830 series, 64G
model).
SSD was with Ext4, discard, noatime, barriers=off. CHS aligned to 32/32.

General observations:
From 4G RAM, kernel allocated 2,7G to buffers.
I can expect this level in storage hierarchy (buffers) will be slower
that RAM but faster than any next in hierarchy storage level (physical
mass storage).
Also I configured 32M query cache to mysql in hope that DB reads fill be
mainly from cache. Other parameters were set to mysqltuner.pl suggestions.
I configure /tmp as tempfs in hope that all temp SQL tables will be
written-read from RAM based mass storage.

After move HDD to SSD:

Results:
Qualitative:
-On FE I practically didn't notice any subjective speed-up.
-Only area where speed-up is seen is mythweb (was instant, with SSD is
flashy)
-I can definitely say: it is NOT a case where SSD-based system was slow
like HDD-based one. It is a case where HDD-based system is the same fast
like SSD (for justification of such statement pls go to end of this post).

Quantitative:
Here are OS boot & scheduling comparisons:

HDD boot:
Jan 11 14:36:54 Startup finished in 3s 54ms 736us (kernel) + 56s 995ms
395us (userspace) = 1min 50ms 131us.
(I have so long userspace as I add 45sec zoneminder start delay)

HDD scheduling:
2012-01-11 14:53:42.959000 I Scheduled 381 items in 5.7 = 3.44 match +
2.22 place
2012-01-11 15:46:22.516929 I Scheduled 379 items in 5.8 = 3.50 match +
2.27 place
2012-01-11 15:51:17.644414 I Scheduled 379 items in 5.9 = 3.55 match +
2.36 place
2012-01-11 15:56:16.214845 I Scheduled 379 items in 5.9 = 3.55 match +
2.37 place
2012-01-11 15:57:53.363886 I Scheduled 379 items in 2.4 = 0.00 match +
2.35 place
2012-01-11 15:59:50.008540 I Scheduled 379 items in 2.4 = 0.00 match +
2.36 place
2012-01-11 16:07:13.492971 I Scheduled 378 items in 6.0 = 3.74 match +
2.26 place
2012-01-11 16:11:16.104133 I Scheduled 378 items in 5.9 = 3.73 match +
2.21 place
2012-01-11 16:16:16.588279 I Scheduled 378 items in 5.7 = 3.55 match +
2.20 place

SSD boot:
Jan 11 11:57:26 Startup finished in 4s 541ms 296us (kernel) + 52s 835ms
494us (userspace) = 57s 376ms 790us.

SSD schedulling:
2012-01-11 12:07:04.334242 I Scheduled 383 items in 6.0 = 3.56 match +
2.39 place
2012-01-11 12:10:03.098568 I Scheduled 382 items in 2.4 = 0.00 match +
2.36 place
2012-01-11 12:11:15.145393 I Scheduled 382 items in 5.8 = 3.47 match +
2.36 place
2012-01-11 12:16:16.925119 I Scheduled 382 items in 5.9 = 3.53 match +
2.35 place
2012-01-11 12:21:16.627705 I Scheduled 382 items in 5.8 = 3.47 match +
2.33 place
2012-01-11 12:26:14.412831 I Scheduled 382 items in 5.9 = 3.51 match +
2.35 place
2012-01-11 12:31:16.768138 I Scheduled 382 items in 5.9 = 3.50 match +
2.39 place
2012-01-11 12:35:31.710289 I Scheduled 382 items in 6.0 = 3.55 match +
2.44 place

My conclusions:
1.In case of my system build-in-kernel disk buffering is so effective
that even significant speedup of next level storage hierarchy (HDD->SSD)
is totally masked by kernel buffering.
2.Big enough MySQL caches quite effectively masks speedups in mass-storage.
3.Recordings rescheduling speed is directly correlated to CPU (going
from Celeron 3,46G to AMD 235E changed reschedule time from 60s to 18s).
4.For rescheduling speed-up, next, after CPU upgrade & mysql caches, is
moving /tmp to tempfs (noticeable speedup 18s->6s).
5.Current MythTV system based on quite standard HDD like WD Green is
working really nice even with ATOM CPU. (i.e.86 progs EPG list loads in
aprox 0.2-0.4sec; showing 400+ recordings list is instant (in sense that
there is no time to show loading progress dialog).

Summarizing:
Speaking in economy: HDD->SSD marginal utility increase is in my case
was ABSOLUTELY not worth of SSD investment.

Before SSD spending decision I'm strongly recommending:
-buy more RAM for having huge as possible kernel disk buffers
-move /tmp to tempfs
-allocate 32MB or more for MySQL query cache (and other parameters
accordingly to http://mysqltuner.pl/)
With above it is highly probable that You will get MythTV system where
HDD->SSD upgrade will absolutely not worth the money (and allows You
spent those money elsewhere - with much higher utility).

-br

BTW: I replaced my desktop HDD (Caviar Black 1TB) with this SSD. I'm on
MAC OSX 10.7.3.
Here SSD plainly SCREAMS.
I.e launching program or restoring it's window are practically
indistinguishable.

Attachments:

warpme.vcf (83 B)

ron at ronfrazier

Jun 7, 2012, 4:47 AM

Post #5 of 8 (704 views)
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Re: SSD for speed up FE/BE [In reply to]

On Wed, Jun 6, 2012 at 6:15 PM, Preston Crow
<pc-mythtv08a [at] crowcastle> wrote:
> An SSD file system must support TRIM or performance will be sub-par, so EXT3
> is out. �EXT4 is a fine choice.

Lets be clear here. When you say "sub par", you just mean "slightly
slower than it could be". You make it sound bad, but it's not. Even
without trim, performance will be orders of magnitude better than a
regular hard disk. And lack of TRIM only affects writes. For read
operations there's no difference.

My myth system has an SSD that doesn't support TRIM (1st generation
Intel), and the improvements are remarkable vs a HDD. The system I
originally took that drive out of was upgraded with a newer SSD that
does support TRIM (3rd gen Intel), and from a performance aspect
there's very little difference. I'm sure it would benchmark better,
but from a user experience standpoint, you could probably swap the
drives on me and (other than the capactity) I'd never know the
difference.

That said, I'm not advocating EXT3 or anything (I use EXT4 on my SSD).

--
Ron Frazier
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ron at ronfrazier

Jun 7, 2012, 5:05 AM

Post #6 of 8 (706 views)
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Re: SSD for speed up FE/BE [In reply to]

On Wed, Jun 6, 2012 at 5:52 PM, Josu Lazkano <josu.lazkano [at] gmail> wrote:
> Hello all,
>
> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>
> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
> Mount options?
> 2. Must I host other files on the SSD disk? channel icons? logs?
>
> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
> any help, thanks and best regards.

I started a thread on my SSD upgrade earlier this year, and a lot was
discussed there. Check it out in the archives.

My biggest concern is what sort of "SSD" are you planning to use? When
you say 4-8GB, I don't think they make real SSDs in that size, so you
I'm assuming you mean to get a flash drive (compact flash, SD, memory
stick, etc). If so, my biggest concerns with those would be

1) performance - even though access times should be good, sequential
access will be considerably slower than a HDD. It seems like most
flash cards are limited to 20-30 MB/sec unless you pay more for a high
end one. Overall you'll probably still be better off than an HDD, but
I can't say for certain how much better.

2) longevity - this is even more important. SSDs are designed to
handle tons of writes before they wear out. On the other hand, I've
heard a lot of reports that flash drives wear out much more quickly.
If you can minimize writes to the drive, you can greatly reduce this
issue. With a myth system, your 2 biggest culprits are going to be
logging and mysql. In my other thread (mentioned above) I talked a bit
about this issue and what I found. Specifically, one of the biggest
issues was mysql temporary tables, which are used by myth when it runs
the scheduler. Even with the better longevity of a real SSD, writes
from the scheduler were going to blow through the rated life of the
drive in just a couple years. By moving those temporary table writes
to RAM, writes to the SSD were drastically reduced.

--
Ron Frazier
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jam at tigger

Jun 7, 2012, 6:22 PM

Post #7 of 8 (683 views)
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Re: SSD for speed up FE/BE [In reply to]

On 08/06/2012, at 4:10 AM, mythtv-users-request [at] mythtv wrote:

>> I am thinking on buy a little SSD drive to speed up my Nvidia ION Atom
>> FE/BE system. Actually I host MySQL data directory on 2.5 HDD
>> (5400rpm) EXT4 disk. I have some questions about SSD setup.
>>
>> 1. Which is the best option to host MySQL datadir? EXT3? EXT4? XFS?
>> Mount options?
>> 2. Must I host other files on the SSD disk? channel icons? logs?
>>
>> I am planning on buy a little disk, maybe 4 or 8GB. I will appreciate
>> any help, thanks and best regards.
>
> I started a thread on my SSD upgrade earlier this year, and a lot was
> discussed there. Check it out in the archives.
>
> My biggest concern is what sort of "SSD" are you planning to use? When
> you say 4-8GB, I don't think they make real SSDs in that size, so you
> I'm assuming you mean to get a flash drive (compact flash, SD, memory
> stick, etc). If so, my biggest concerns with those would be
>
> 1) performance - even though access times should be good, sequential
> access will be considerably slower than a HDD. It seems like most
> flash cards are limited to 20-30 MB/sec unless you pay more for a high
> end one. Overall you'll probably still be better off than an HDD, but
> I can't say for certain how much better.

[snip]

I've played with SD cards and with USB mem sticks on my embedded systems.
Despite the hype and specs they are S-L-O-W really SLOW. YMMV but beware.

James

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josu.lazkano at gmail

Jun 9, 2012, 5:50 AM

Post #8 of 8 (669 views)
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Re: SSD for speed up FE/BE [In reply to]

Thanks all, I just add the disk to my system, I format with EXT4:

mkfs.ext4 -L SSD /dev/sdb1

And mount it with this options:

UUID=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx /mnt/ssd ext4
defaults 0 0

I move the datadir to the SSD mount.

I notice that mythweb now is very fast and the recordings screen load faster.

Would I configure something else to get better performance?

Thanks for your help.

--
Josu Lazkano
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