PCI Bottleneck

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greengolftee87

Limp Gawd
Joined
Oct 15, 2008
Messages
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I am currently using this Supermicro card in my server, but only half of it is plugged in to the board. I guess this is the difference between 32 and 64 bit slots? I also have a intel pro 1000 gig PCI nic in there as well.

Anyway, while observing hdd transfer speeds i noticed that they really never break about 55 MB/s. This is both with the windows copy feature and my frequent use of robocopy. This bottleneck also appears over the network. Is this because the PCI bus is shared? In my head it went something like this. Available bandwidth =133, so divide by 2 because data has to go in and out so ~66 - some overhead and crap puts me about right where I am.

In the future ill want to upgrade this mobo so would I notice added benefit of a PCI 64 bit slot with that card
 
PCI-X is considerably faster than PCI as you've just found out. I wouldn't bother looking for a board with anymore though because nothing uses it. You can find a few modern boards out there with it, but you'll probably wind up paying more for a board with PCI-X than getting one without it and the PCIe version of that card.
 
Well, that card is meant for a 64bit PCI-X slot running 133 mHz, which should provide it 1000MB/sec of bandwidth.

On that 32 bit slot running 33mHz you are getting 100MB/sec tops. Thats the max of any standard PCI slot.
 
staticlag said:
Well, that card is meant for a 64bit PCI-X slot running 133 mHz, which should provide it 1000MB/sec of bandwidth.

On that 32 bit slot running 33mHz you are getting 100MB/sec tops. Thats the max of any standard PCI slot.
Click to expand...

so is the PCI bus full duplex. should i be getting 50 MB/s or 100 MB/s from drive to drive
 
unfortunately half-duplex,

50MBsec drive to drive sounds about right.

What speeds do you get on other drives in the box?

How much RAM do you have in the box?
 
1 gig of ram in the box but the drives are fast. 2x seagate 1.5 tb and 2x hitcahi 2tb, im ok with these speeds for now, i just wanted to make sure that im maxing out whatever i can
 
A cheap Dual P3 Tyan or Supermicro board from Ebay might be a good chioce. They are only 64/66 PCI but can near enough max out a Gbit connection. I have Single P3 on Tyan Thunder LE-T with Pro1000MT and Areca PCI-X raid card and get near enough max gbit transfers. Power usage is surprisingly low too.
 
I would reconsider investing money in PCI-X; if you can get these stuff for free; sure. If you have to pay big bucks for it, you might just want to consider PCI-e with a new motherboard. Any PCI-X controller will have severely limited use as of this point; it only runs on older systems, may have performance problems especially when inserted in normal PCI slot and probably costs the same as the superior PCIe option.

It may also have a limited economical lifetime, as it cannot made to work on any newer system; you're tied to the older generation PCI-X chipsets; though older server boards also have PCI-X + PCI-e; newer systems won't.

One of these two might be a suitable substitute, and they work with regular PCI-express:
http://www.supermicro.com/products/accessories/addon/AOC-USAS2-L8i.cfm?TYP=E (6Gbps)
http://www.supermicro.com/products/accessories/addon/AOC-USAS-L8i.cfm (3Gbps)

They both can connect 8 SATA HDD using the two mini-SAS cables (each cable splits in 4 SATA).
 
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