Importance of pci-e slot speed?

[HK-Steve]

Hi Everyone,

I was messing with my Towers and saw that I have only 1x pci-e slot at 16x speed. 3 pci-e slots on the motherboard.

With 2x SAS controllers installed speed goes down to 4x speed per slot.

 

I have 2x 9207-8i's installed, So would the 4x speed instead of 8x speed for the SAS controllers on the bus, be slower because of this??

Parity checks would be slower, data transfers, etc.

Talking about real world not hypothetical, which would mean a new motherboard for me, but worth it as the 9207's are new to replace the SuperMicro controllers. 

 

Much appreciated

Steve

[Vr2Io]

Depends on how many drive attach and bandwidth need.

[HK-Steve]

Thanks Benson, I did kind of leave the question open ended. Sorry.

I currently have 3x Towers,

 

My new Tower 3 has 12x 8Tb hard drives with 2x 9207-8i's, 2x parity and 10x data drives. This is the reason for the question..

My Tower 2 has 24x 2Tb drives. 2x SuperMicro and 1x LSI 9211-8i's, 2x parity. yes need to replace the SuperMicro..

My Tower 1 has 24x 2Tb drives. 3x LSI 9211-8i's with 2x parity.

 

My new Tower 3 is the reason for the question, Tower 1 and 2 are doing really well with a parity check about 70Mb/s, older motherboards and older hard drives.

Tower 3 is about the same speed with newer CPU, RAM and Motherboard, Thought it would be faster, as it is also about 70Mb/s parity check.

 

Hope that helps and appreciate your thoughts.

[Vr2Io]

Strange, even 4x PCIe 3.0 for 9207, with attach 8 hdds, it should no bottleneck.

 

Pls check does any 9207 run in PCIe 2.0 in 1x. in diagnostic log. Sure PCIe bandwidth also important.

 

My tower mix 10TB, 8TB, 6TB, total 13disks with 9207+expander in 8x. Parity check max at 189MB/s. My 2nd tower with 9211 and 12 disks also same.

Edited June 4, 2019 by Benson

[HK-Steve]

Benson, could you list your hardware?
Would be nice to see what makes yours that fast..

 

Will do for the pci-e when I get time later this week.

 

Much appreciated.

[Vr2Io]

1 hour ago, HK-Steve said:

could you list your hardware?

Hardware not special, list 2nd tower FYR, sure you will got faster speed once have best PCIe slot arrangement.

 

Intel G3250 (dual core CPU), B85 mainboard, 3TB x1 + 6TB x11, 8GB DDR3 RAM, 9211@1st 16x slot, 6Gbps expander in dual link.

 

Pls note, 189MB/s was talking about max at start, average as below, speed increase due to disk change, bottleneck in disks not 9211.

 

Edited June 4, 2019 by Benson

[HK-Steve]

Thanks Benson,

Well after reading many many threads here, I found a post by johnnie.black with the tuneable setting for disks.

I changed to the suggested and BAM, parity check speed went straight to 168Mb/s which is awesome from the original 71Mb/s..

 

Settings -> Disk Settings

Tunable (md_num_stripes): 4096

Tunable (md_sync_window): 2048

Tunable (md_sync_thresh): 2000

 

Thanks to you Both.

Much appreciated

[Vr2Io]

That's good.

 

On 6/3/2019 at 11:41 PM, HK-Steve said:

Parity checks would be slower, data transfers, etc.

Weird, I never got parity check slow, but I got data transfer slow since 6.7 and fixed by those tunable too.

 

Edited June 5, 2019 by Benson

[HK-Steve]

Will let you know what the transfer speeds are like after parity check is finished. Thanks

[HK-Steve]

Transfer speeds stayed the same, just over 110Mb/s

[chickensoup]

On 6/4/2019 at 9:47 PM, Benson said:

Hardware not special, list 2nd tower FYR, sure you will got faster speed once have best PCIe slot arrangement.

 

Intel G3250 (dual core CPU), B85 mainboard, 3TB x1 + 6TB x11, 8GB DDR3 RAM, 9211@1st 16x slot, 6Gbps expander in dual link.

 

Pls note, 189MB/s was talking about max at start, average as below, speed increase due to disk change, bottleneck in disks not 9211.

 

(Screenshot omitted)

 

Hey Benson, 

 

Is that table of Parity speed history a plugin? I can't check mine right now sorry as it's out of action. If it's part of 6.7, would you mind sharing how to get to it? 

 

Thanks! 

 

[Vr2Io]

7 hours ago, chickensoup said:

Is that table of Parity speed history a plugin? I can't check mine right now sorry as it's out of action. If it's part of 6.7, would you mind sharing how to get to it?  

It is not a plugin, it is a buildin function, may be you never execute parity / read check, so haven't that history show.

Edited June 9, 2019 by Benson