Author Topic: Hardware Chat - I/O Handling  (Read 2570 times)

Armor Gnome

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Hardware Chat - I/O Handling
« on: August 18, 2012, 07:39:20 pm »
New beta, new core build

I thought I knew hardware, however after discussing the differences between cpu/gpu bound applications and I/O bound applications I realized I have room for some more knowledge.  I built my current hybrid much like someone would build a gaming rig or MD.  I selected what was at that time a nice video card, a mobo with a mutlicore capable socket and 2 gigs of ddr2 ram. -There was a great comment on the forums about ram requirements that said something about not needing more than 2gigs even with 40 MDs and a climate controlled dog house-  Though I saw the humor in this and followed the recommendation I never quite understood how more ram wouldn't help out.  Well I get this part of it now and am ready to reconsider and rebuilt my core.  Where I used to think I/O was devices connected to the machine, I now understand that all the way down to C++ programs have I/O needs and are only as fast as they can get their I, process it and then O.

A balanced system outperforms a one-device wonder.  So I am looking at timings on things like fsb, memory controllers and ram to get things in-line.  Adding disk writes into this balancing act is where I realize I could use some help.  My current plan is to add a PowerEdge as a core and here is why I think it will be beneficial, if you have suggestions or reasons why this might not give me a good experience please comment.

PowerEdge 2850 or 6850, 4GB ram, 3 small scsi drives in RAID 5

I selected this model for the used price of less than $200, the duel processors with individual memory controllers, its expandability to 16/32? GB memory.  The low cost of server memory compared to desktop memory and the use of 15k SCSI drives.  I then will do a hybrid install using the onboard vga and simply turn off autostart mediadirector option after install.  I think this setup will give me the best I/O capabilities and though processing power may be overkill I will be able to take advantage of things like motionwrapper watching multiple cams at higher frames per second than I am capable of currently with my core.  I know the RAID choice will probably result in some debate but my choice for 5 is based on the use of NAS for everything except system files and my willingness to do frequent backups for recovery in the event of a drive failure.  If another RAID configuration will offer lower latency at the cost of less drive failure persistence and the elimination of write holes I am willing to listen.

I could post this a million other places on the internet where hardware discussions go on, I appreciate anyone who takes their time to comment on their experiences here on this forum about hardware interactions within this specific software environment.

**Edit.  My used hardware supplier recommended an Opteron model over a Xeon model, apparently the memory controllers are very different?
« Last Edit: August 18, 2012, 07:48:29 pm by Armor Gnome »
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Re: Hardware Chat - I/O Handling
« Reply #1 on: August 18, 2012, 08:07:12 pm »
Don't know about the memory controllers, and I don't know if that'd be your bottleneck ,... But you might want to consider making the second nic a high speed/good quality Intel chipset card using the high speed PCI express bus/slot that you might normally have put the graphics card in.

Something like this:

Personally, as far as even MDs go the middling range of graphics chipsets, even the Intel ones (excepting the PowerVR based ones, if course), are powerful enough to handle 99% of what you'd be throwing at it as a relatively well performing MD. A 3-4 year old Intel GMA 3150 might choke with 1080p playback with the Xine engine (but 90% of content is 720p or lower)... The UI doesn't tax the system much. Beneficial things would be hardware decoder support for media playback, vdpau, etc., more so than triangles per second. Of course, high end graphics cards usually have that too.

I'd also consider pulling the HDs from the MDs,... modest power savings, but more importantly, less heat (MDs are often tucked away). And why waste the drives? Store 'em for later use...
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