[mythtv-users] Bad News for me...a warning to all

[Debabrata Banerjee]

#1 The sx4000 linux driver blows, and yes - it comes with binary only
drivers for a stock kernel in redhat 7.3 out of the box. Good luck.... I
sold mine.
#2 So do most proprietary hardware raid5 solution's drivers.

Software raid 5 is often faster than hardware raid 5, except it has higher
cpu usage. WinXP != linux

Check your kernel output when loading the raid5 driver, here's mine:

raid5: measuring checksumming speed
   8regs     :  3262.800 MB/sec
   32regs    :  2404.800 MB/sec
   pIII_sse  :  3499.200 MB/sec
   pII_mmx   :  5003.200 MB/sec
   p5_mmx    :  6418.000 MB/sec

Yeah, that's 6.4GB/sec at 100% cpu usage. Since my disks will never approach
that the maximum cpu usage will be much less. I'd estimate I'm getting about
5-10% with full-on (90-130MB/s) reads with 6 disks with shared channels,
about 150 MB/s on one drive per channel and just barely more cpu usage. 2
Drives per channel really cleans up the cable mess which the hardware cards
don't let you do.

So what exactly is the "demand of streaming continious MPG" that everyone
keeps overestimating by a light year?, I have yet to figure out why. The
maximum pvr250 bitrate is only 2MB per second. Any drive from 1997 can do
that. I have a single drive doing 3 record streams and one playback just
fine, two cards and one frontend being remote, total network bandwidth is
less than 1MB per second.

-Debabrata

----- Original Message ----- 
From: "Ed Benckert" <ed at ebonmists.com>
To: "Discussion about mythtv" <mythtv-users at mythtv.org>
Sent: Friday, April 23, 2004 2:38 PM
Subject: Re: [mythtv-users] Bad News for me...a warning to all


> Software Raid 5 offers terrible performance... its ok for word documents
and
> the like, but theres no way the cpu/drives will keep up with the demand of
> streaming continious MPG data to the drive, as well as reading it back at
> the same time.
>
> It's expensive, but a beautiful solution: Promise Technology Raid 5 ATA
> controller cards. Here's a link to one:
>
> http://www.cluboverclocker.com/reviews/raid/sx4000/
>
> That is a 4 channel/4 drive card. I have the 6 channel/6 drive card. It's
a
> true hardware raid solution for ATA100/133 drives. I paid $250 for mine.
>
> I do a lot of video editing and the like, and storing a DVD on a hard
drive
> eats up space, so I need a lot. When a drive goes bad and you have no good
> soilution to back up a few 120 gig drives... you lose a lot of data and
you
> want to murder youself :)
>
> I had a Highpoint Raid 5 controller card, but thats crap. It's basically
an
> ATA100 controller card with 4 controllers (8 channels/drives) that has
> software raid built into the drivers. The performance was ABYSSMAL. I had
5
> 80 gig drives in a 320gig raid 5 array, and I couldnt move my USB mouse
> around the screen on my WinXP system without it pausing every second or so
> as the CPU choked doing the raid computations.
>
> The Promise card is a true hardware raid. And if I remember correctly,
comes
> with Linux drivers right in the box.
>
> Oh, in addition you need to give it a DIMM for it's cache memory, there is
> none on-board. It takes up to 128mb... so right now I have a 5 drive (80gb
> each) RAID 5 system, 320gb of space, with a 128mb cache. It's beautiful.
>
> And I've already had a drive go bad on me (it was 4+ years old). Bought a
> new drive, popped it in, rebuilt the array... and my PC was back.
>
> Love it. Cant reccomend it enough.
>
>
> Jason Donahue wrote:
> > Watch out for over heating everybody!!! I have (had) a micro-atx case
> > running my Myth setup...200GB Drive, and 2 tuner cards. All this in a
> > micro atx case generated a LOT of heat...I mean a LOT.
> >
> > Add to this, the enclosed cabinet wher my HT equipment is held...no
> > circulation.
> >
> > Well, easy to uess, my system got to hot...killed the power supply,
> > which in turn somehow fried my Hard Drive. EVERYTHING lost. ouch.
> >
> > I finally had every setting PERFECT. DAMN.
> >
> > Now I get to start all over. This time I will be using network storage
> > (nfs mounted from a data server, in a nice BIG and COOL case).
> >
> > Additionally, I plan on using software RAID 5, so I have the data
> > redundancy. I also plan on moving 1 tuner into the frontend box in my
> > bedroom...try to distribute the heat from those things.
> >
> > Anyway, thought I'd warn anyone out there...If your case seems really
> > hot - prepare for disaster.
> >
> >
> >
> > ------------------------------------------------------------------------
> >
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>


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