Mailing List Archive: MythTV: Users

New Myth setup - questions about storage.

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cass at casscoenterprises

Dec 28, 2009, 8:50 AM

Post #1 of 10 (1022 views)
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New Myth setup - questions about storage.

I am rebuilding my mythbox to take advantage of 4 new 640GB drives that I
now have. I am planning on putting them together in a RAID5 array for
recordings and to use as a file server for all the computers on my home
network.

I am planning on putting the OS on a separate hard drive, and therein lie my
questions. I have a few hard drives to choose from, a 80GB ide, 120GB ide,
a 160 GB SATA, and a 500GB SATA. I would prefer to use the SATA drives in
other computers in the house, but I am concerned about system performance
using the slower ide drives as the OS drive. The optical drive in this
system is also an ide drive, although it doesn't get much use. I am aware
of performance issues with a hard drive and an optical drive sharing the
same channel, but I only rip the (very) occasional DVD; I never use it as a
CD or DVD player since the mythbox is hidden away in a closet. The
motherboard in this system (Gigabyte M57SLI-S4) only has 1 ide channel, so
the OS drive and optical drive would have to share it.

Should I use the ide drive as my main drive?

Are there any issues with using ide and sata in the same system?

I have recently seen threads regarding performance issues with ext4. What
filesystems should I use for the RAID5 and OS drives?

I have the option of using a SATA optical drive in this system. Would it be
more beneficial to use both ide drives: one for OS, one for MYSQL?

Other relevant system specs: Athlon X2 4800+, NVidia 9500GT, 2 GB ram, HD
PVR, Hauppage HVR-1600. I will be running .22-fixes and Fedora 12.

Any feedback would be appreciated!

-Derek

linux at thehobsons

Dec 28, 2009, 9:11 AM

Post #2 of 10 (984 views)
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Re: New Myth setup - questions about storage. [In reply to]

Derek Cass wrote:

>I am rebuilding my mythbox to take advantage of 4 new 640GB drives
>that I now have. I am planning on putting them together in a RAID5
>array for recordings and to use as a file server for all the
>computers on my home network.
>
>I am planning on putting the OS on a separate hard drive, and
>therein lie my questions. I have a few hard drives to choose from,
>a 80GB ide, 120GB ide, a 160 GB SATA, and a 500GB SATA. I would
>prefer to use the SATA drives in other computers in the house, but I
>am concerned about system performance using the slower ide drives as
>the OS drive. The optical drive in this system is also an ide
>drive, although it doesn't get much use. I am aware of performance
>issues with a hard drive and an optical drive sharing the same
>channel, but I only rip the (very) occasional DVD; I never use it as
>a CD or DVD player since the mythbox is hidden away in a closet.
>The motherboard in this system (Gigabyte M57SLI-S4) only has 1 ide
>channel, so the OS drive and optical drive would have to share it.
>
>Should I use the ide drive as my main drive?
>Are there any issues with using ide and sata in the same system?

For reference, I have a single WD 'Green' drive in my backend - and
that's a Xen box running 4 VM of which Myth is just one. Just a
single tuner, but doing multirec.

Mixing IDE (aka PATA) and SATA should not be a problem. And any of
your drives should be OK for the OS and Myth program/DB.

I think general consensus on the list has been that you don't really
need to use RAID for your Myth storage - Myth will do some balancing
between drives and in general you don't need huge bandwidth off any
single drive (but that depends on your usage - particularly if you do
commflagging or transcoding). So it might be better to split the
drives up and have part of each one in a raid array for your file
server, and the rest as single drives for Myth storage.

--
Simon Hobson

Visit http://www.magpiesnestpublishing.co.uk/ for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.
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drescherjm at gmail

Dec 28, 2009, 9:15 AM

Post #3 of 10 (981 views)
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Re: New Myth setup - questions about storage. [In reply to]

> Should I use the ide drive as my main drive?
>
This is up to you. I personally would not bother using any drive that
is 3 years old or more as an OS drive.

>
> Are there any issues with using ide and sata in the same system?
>
No. At least I have not seen this on dozens of linux machines at wor.

> I have recently seen threads regarding performance issues with ext4. What
> filesystems should I use for the RAID5 and OS drives?
>

ext4 for both. ext3 is annoyingly slow for large file operations. xfs
is slow for small files.

>
> I have the option of using a SATA optical drive in this system.

Does not really make a big difference if the optical drive is SATA or ide.

> Would it be
> more beneficial to use both ide drives: one for OS, one for MYSQL?
>
>
>
> Other relevant system specs: Athlon X2 4800+, NVidia 9500GT, 2 GB ram, HD
> PVR, Hauppage HVR-1600. I will be running .22-fixes and Fedora 12.
>
Make sure you setup your system for vdpau.
>
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match at ece

Dec 28, 2009, 3:31 PM

Post #4 of 10 (961 views)
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Re: New Myth setup - questions about storage. [In reply to]

On 28 Dec 2009 at 11:50, Derek & Cindi Cass wrote:

> I am rebuilding my mythbox to take advantage of 4 new 640GB drives that I now have. I am
> planning on putting them together in a RAID5 array for recordings and to use as a file server for
> all the computers on my home network.
>
> I am planning on putting the OS on a separate hard drive, and therein lie my questions. I have a
> few hard drives to choose from, a 80GB ide, 120GB ide, a 160 GB SATA, and a 500GB SATA. I
> would prefer to use the SATA drives in other computers in the house, but I am concerned about
> system performance using the slower ide drives as the OS drive. The optical drive in this system
> is also an ide drive, although it doesn´t get much use. I am aware of performance issues with a
> hard drive and an optical drive sharing the same channel, but I only rip the (very) occasional
> DVD; I never use it as a CD or DVD player since the mythbox is hidden away in a closet. The
> motherboard in this system (Gigabyte M57SLI-S4) only has 1 ide channel, so the OS drive and
> optical drive would have to share it.
>
> Should I use the ide drive as my main drive?
> Are there any issues with using ide and sata in the same system?
> I have recently seen threads regarding performance issues with ext4. What filesystems should I
> use for the RAID5 and OS drives?
> I have the option of using a SATA optical drive in this system. Would it be more beneficial to
> use both ide drives: one for OS, one for MYSQL?
>
> Other relevant system specs: Athlon X2 4800+, NVidia 9500GT, 2 GB ram, HD PVR, Hauppage
> HVR-1600. I will be running .22-fixes and Fedora 12.
>
> Any feedback would be appreciated!
>
> -Derek
>

My backend runs 6 750GB SATA drives for storage, configued as 3 1.5TB
raid 0 arrays, since I'm most concerned with maximizing storage space. I
have run XFS on my storage drives for many years, with nary a hicup.

My system disk is a 40 GB IDE drive that shares the cable with a BluRay/HD-
DVD drive. This system disk is about twice as big as it needs to be. It runs
EXT3.

Both the OS and MySQL are on the system disk. The storage arrays have all
the recordings, music, RIPs.

It's dedicated to being a MythTV backend/frontend only, as I have another
server on my home network for everything else. My system has been rock-
solid for years.

In my case, on my hardware, this configuration has been very well-behaved.

YMMV

Marvin

match at ece

Dec 28, 2009, 3:31 PM

Post #5 of 10 (967 views)
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Re: New Myth setup - questions about storage. [In reply to]

jarpublic at gmail

Dec 28, 2009, 4:09 PM

Post #6 of 10 (973 views)
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Re: New Myth setup - questions about storage. [In reply to]

> My backend runs 6 750GB SATA drives for storage, configued as 3 1.5TB raid
> 0 arrays, since I'm most concerned with maximizing storage space. I have run

This doesn't make any since to me. Mythtv doesn't need the extra
throughput, and with storage groups you still get all the storage
space. So by running RAID0 all you have gained is double the
likelihood of loosing your recordings.
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drescherjm at gmail

Dec 28, 2009, 4:13 PM

Post #7 of 10 (976 views)
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Re: New Myth setup - questions about storage. [In reply to]

On Mon, Dec 28, 2009 at 7:09 PM, Johnny <jarpublic [at] gmail> wrote:
>> My backend runs 6 750GB SATA drives for storage, configued as 3 1.5TB raid
>> 0 arrays, since I'm most concerned with maximizing storage space. I have run
>
> This doesn't make any since to me. Mythtv doesn't need the extra
> throughput, and with storage groups you still get all the storage
> space. So by running RAID0 all you have gained is double the
> likelihood of loosing your recordings.
>
I Agree. With mythtv there is no good reason for using raid 0. I was
just typing the same when gmail told me that someone added a message
to the thread.

I would also add that using LVM to connect a bunch of non raid drives
together is also not a good thing to do. There is no need for
everything to be in 1 filesystem. Much better to let mythtv handle
this with storage groups.

John
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match at ece

Dec 29, 2009, 9:00 AM

Post #8 of 10 (938 views)
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Re: New Myth setup - questions about storage. [In reply to]

On 28 Dec 2009 at 19:13, John Drescher wrote:

> On Mon, Dec 28, 2009 at 7:09 PM, Johnny <jarpublic [at] gmail> wrote:
> >> My backend runs 6 750GB SATA drives for storage, configued as 3 1.5TB raid
> >> 0 arrays, since I'm most concerned with maximizing storage space. I have run
> >
> > This doesn't make any since to me. Mythtv doesn't need the extra
> > throughput, and with storage groups you still get all the storage
> > space. So by running RAID0 all you have gained is double the
> > likelihood of loosing your recordings.
> >
> I Agree. With mythtv there is no good reason for using raid 0. I was
> just typing the same when gmail told me that someone added a message
> to the thread.
>
> I would also add that using LVM to connect a bunch of non raid drives
> together is also not a good thing to do. There is no need for
> everything to be in 1 filesystem. Much better to let mythtv handle
> this with storage groups.
>
> John

Yes, of course RAID 0 serves little purpose here. The configuration is left
over from years ago, when this backend machine doubled as my main
network server, and before storage groups. Not even sure it was "needed"
then, but it cost nothing and seemed the best way to create what was at the
time 3 huge filesystems, which was beneficial before storage groups. The
choices were software RAID, hardware RAID, or LVM. I chose software
RAID because it was free and I had some history with it (old habits die hard),
and because I never really trusted LVM for no real reason. LVM always felt
like a hack to me.

Anyway, all tasks except MythTV moved to another server years ago. I just
upgraded this backend from MythBuntu 9.04/0.21 to MythBuntu 9.10/0.22 a
couple of months ago and since this was an upgrade of software only, I
didn't bother to change the drive configuration. If the upgrade had failed, I
likely would have.

I included the reference to using my disks in 3 RAID 0 arrays in my response
because the original poster was considering a RAID 5 array and mixing IDE
and SATA drives and asked "Will this work?" Even though my arrays are
RAID 0, I felt that my success story would help to answer his questions.

Yes it will work, if you use reasonable hardware. Wether or not it's the best
configuration is a different question. :-)

Marvin
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junk_inbox at verizon

Dec 29, 2009, 10:05 AM

Post #9 of 10 (929 views)
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Re: New Myth setup - questions about storage. [In reply to]

>
> I am rebuilding my mythbox to take advantage of 4 new 640GB drives that I
> now have. I am planning on putting them together in a RAID5 array for
> recordings and to use as a file server for all the computers on my home
> network.
>
<snip>

> I am planning on putting the OS on a separate hard drive, and therein lie
> my questions.
>
<snip>

>
Like many others have said already, I also feel that using a RAID array for
recordings is not necessary. I do, however, have my OS and Database on my
root disk, which is a Raid-1 mirrored 200GB SATA disks.

I use 6 SATA drives for video storage, sdc through sdh, 5 of which are
500GB, and one is 1TB. (All were 500GB initially, but one got replaced with
a 1TB drive before it failed completely...)

I had initially setup this system with 6x500GB drives in a software Raid 5
configuration, but after a dual HDD failure and losing *every* recording a
year or so ago, I switched to Storage groups. Granted, a dual HDD failure
*should* be rare, but at least if two drives were to fail now, I'd only lose
1/3 of my recordings instead of all of them. (This is just TV after all!)

So I'd just Raid the OS and Database disk, and run individual disks for the
Video/Recordings disks.

Anyways, just my 2 cents...

J-e-f-f-A

newbury at mandamus

Dec 29, 2009, 4:24 PM

Post #10 of 10 (904 views)
Permalink

Re: New Myth setup - questions about storage. [In reply to]

Derek & Cindi Cass wrote:
> I am rebuilding my mythbox to take advantage of 4 new 640GB drives that
> I now have. I am planning on putting them together in a RAID5 array for
> recordings and to use as a file server for all the computers on my home
> network.
>
>
>
> I am planning on putting the OS on a separate hard drive, and therein
> lie my questions. I have a few hard drives to choose from, a 80GB ide,
> 120GB ide, a 160 GB SATA, and a 500GB SATA. I would prefer to use the
> SATA drives in other computers in the house, but I am concerned about
> system performance using the slower ide drives as the OS drive.

I doubt that the ide drives will be appreciably slower than the sata
drives. On gotcha however, is that some motherboards (at least some with
an AMI Bios, get horribly confused if you attempt to mix ide and sata
drives in the same box. I cannot now remember the Asus mb which did this
to me, but one did. It persisted in making the first sata drive (as it
saw them) into sda, and nothing I could do would change that. It was
perfectly happy with an ide dvd drive on the ide channel, but the ide HD
was *always* going to be sdb or higher. I took it back..

As to splitting the OS to another drive, the problem to be avoided,
besides actual hard drive death, is a run-away error condition which
fills /tmp and /var. Put /home on its own partition, point mysql into
that partition (by symlink is easy) and possibly /var/www/html (or
whatever your http doc_root is) so they do not get trashed.

Then if /tmp runs away, nothing gets damaged. ( I filled /tmp on the
weekend by forgetting to stop a 'azap' and 'cat /dev/dvb/adapter... >
/tmp/junk.ts' My myth instance stopped showing any recordings, but no
damage was done.) Well worth the peace of mind.

As to the video storage, well it's only TV. I would rather split it
between drives, than RAID it. BUT if it is also a file server, different
considerations apply.

Geoff

--
Please let me know if anything I say offends you.
I may wish to offend you again in the future.

Tux says: "Be regular. Eat cron flakes."
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