5.1 - PCI M.2 SSD: Trim Enabled or Internal but not both?

[harlansmart]

h9826790,

Cheers again, you must love this, kudos to you Sir.

What would you do, have you any ideas how I can get back to where I was, before I (stupidly) wanted OS X HS & APFS disk format.

After 50+ hours messing round, I'd be happy to go back to 2500MB/s R/W on Sierra w/HFS+!

For sure, I most certainly screwed myself, >1001% haha.

Again, a deep bow to your superior knowledge.

======================================

PS: h9826790, did you not say to swap one of the PCIe SSD's into the #2 Slot that had the SONNET USB3.0 Card in it for, 'read speed of the RAID 0 array should go above 2500MB/s' ?

'PCIe slot 3 and 4 share used the same x4 lane. It's impossible to get anything higher than ~1500MB/s by RAIDing the SSD in slot 3 and 4 (even though either of them can achieve 1500MB/s independently). You are bottlenecked by the bandwidth.

If you want faster read speed, you can swap onc of your SSD with the USB 3.0 card, then join the SSD in a RAID 0 array (in your case, make it a single 512GB partition). Then the read speed of the RAID 0 array should go above 2500MB/s, but write speed may still stay slow because lack of TRIM support.' - h9826790

 

[h9826790]

h9826790,

Cheers again, you must love this, and of course, kudos to you Sir.

So, would you possibly care to elaborate, and help us out h9826790?

What would you do, have you any ideas how I can get back to where I was, before I (stupidly) wanted OS X HS & APFS disk format.

Really now, after 50+ hours messing round, I would be (rather) happy to go back to 2500MB/s R/W on Sierra w/HFS+!

For sure, I most certainly screwed myself, >1001% haha.

Again, a deep bow to your superior knowledge.

======================================

PS: Didn't you say to swap one of the PCIe SSD's into the #2 Slot that had the SONNET USB3.0 Card in it?

'PCIe slot 3 and 4 share used the same x4 lane. It's impossible to get anything higher than ~1500MB/s by RAIDing the SSD in slot 3 and 4 (even though either of them can achieve 1500MB/s independently). You are bottlenecked by the bandwidth.

If you want faster read speed, you can swap onc of your SSD with the USB 3.0 card, then join the SSD in a RAID 0 array (in your case, make it a single 512GB partition). Then the read speed of the RAID 0 array should go above 2500MB/s, but write speed may still stay slow because lack of TRIM support.' - h9826790

If your adaptor can’t neogotiate at PCIe 2.0 X4 in slot 2. There is no way you can achieve >1500MB/s.

From memory, someone can force the Mac Pro to run an adaptor at PCIe 2.0 speed via some patch or terminal command etc. I didn’t study that much, but you can search for it.

Once you fix the adaptor neogotiation speed in slot 2. The RAID 0 array performance should improve.

Of coruse, you can buy a new adaptor, but from memory, that’s expensive.