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romansoft

ESXi 6.5 AHCI - Bad write performance

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romansoft

Hi,

 

I have a HP Gen8 Microserver with upgraded CPU&RAM (Xeon + 16GB RAM), running ESXi 6.5, with 3 WD Red disks, in *AHCI* mode. My idea is to use the server as NAS (xpenology) + also running other VMs in the same time.

 
Just in case server breaks, I prefer not having B120i extra RAID layer on my disks, so I could mount them on any other hardware (even a real Synology machine). In other words, I went for AHCI, and disabled B120i, even I'll have my server a bit noisier due to fan increase.
 
So, let's focus in AHCI with ESXi 6.5.
 
First, I got  a first huge performance problem (horrible 2 MB/s speed!!!) which I solved by disabling Vmware AHCI driver and enabling legacy one (full story here: http://www.nxhut.com/2016/11/fix-slow-d ... wahci.html),
 
Then, when I thought all was solved... I noticed that write performance is still bad.
 
My current values with this setup (WD Red 3TB disk) are:
- Read: ~150 MB/s (ok)
- Write:  ~17 MB/s (WRONG!!!!).
 
(measured with a "dd", launched on a Linux cd rescue .iso inside the VM).
 
If I get rid of Vmware and boot from linux-USB, and repeat former tests, I got the expected 150 MB/s write speed (instead of 17!!).
 
It's clear vmware is buggy.
 
Anyone using AHCI with Esxi with no write speed problems? Any solution?
 
 
PD: I didn't investigate that but is it possible to configure B120i to completely bypass (raw) harddisks, without adding any extra bit?
 
Cheers,
-r
 
 

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abtekk

Are you using the HP variant of ESXi?

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romansoft

Yes, HP variant (November 2016).

 

But I don't think this has something to do with the problem, since both AHCI drivers tested (new & legacy one) come from Vmware's side, not HP's.

 

I mean, I'm aware of driver problems with B120i (that's HP's fault indeed) but I'm not using those drivers (in case I'd decide to switch from AHCI to B120i, I know I'd have to downgrade to v.88 of hpvsa).

 

PS: It's very sad both HP and Vmware have these huge faults in 2017!

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abtekk

Yes, HP variant (November 2016).

 

But I don't think this has something to do with the problem, since both AHCI drivers tested (new & legacy one) come from Vmware's side, not HP's.

 

I mean, I'm aware of driver problems with B120i (that's HP's fault indeed) but I'm not using those drivers (in case I'd decide to switch from AHCI to B120i, I know I'd have to downgrade to v.88 of hpvsa).

 

PS: It's very sad both HP and Vmware have these huge faults in 2017!

 

Looking at historical threads of similar issues, it looks like ESXi is known to have issues with the B120i in its entirety (AHCI or otherwise), and people have switched to the P222 because of it. See below:

 

 

3. ESXi 6.0 is fine with 2x WD Red 3TB in RAID1 with the b120i but performance is awful. Reads will be fast but writes will linger around 20-30MB/s. The SSD was attached to the ODD port at the time.

4. ESXi 6.0 is fine with 4x WD Red 3TB in RAID5 with a P222 and performance is very good both ways. The Sandisk SDSSDXP-120G on port 1 of the b120i again caused mystery issues like the datastore scanning delays. Removing the SSD or disabling the b120i controller entirely fixed it.

 

http://homeservershow.com/forums/index.php?/topic/9141-low-io-performance-with-esxi-60/page-3#entry99246

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romansoft

Yes, but those posts are quite old so I thought they could be solved (seems they're not).

 

P222 is expensive. I could buy a cheaper pcie SATA card (I didn't investigate yet) for serving SSD drive with ESXi datastore and then enable VTd's complete pass-through of original HP Gen8's Cougar AHCI/SATA card to VM (it's an Xpenology).

 

But I wanted to use the only pcie slot available in Gen8 for a gfx card (+hdmi audio). That's the reason I didn't go for the former "solution".

 

Cheers,

-r

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romansoft

@tomaash: please, read my original post carefully. As I said, that's the 1st fix I applied before creating this thread. It fixed read speed problem but NOT write speed.

 

Cheers,

-r

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tomaash

Sorry, been too quick.

Yeah, vmware does love enterprise raid controllers. I ended up reinstalling back to 6.0 after having issues with ahci, that was not on hp hardware though (intel desktop board with q77 chipset)

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romansoft

Interesting... so may be older vmware versions "fix" the problem (btw, Cougar AHCI card is only supported by Vmware ESXi 6.5, acording to Vmware compatibility page).

 

It's a little bit painful but maybe I'll give ESXi 6.0 update 2 a try (as a side effect, I'll "recover" vsphere client app).

 

Cheers,

-r

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anogues

Hello.

 

I had the same problem. Solution is to create an array and move from ahci. You can create an array in raid 0, with only one disk. Which will be the same as the ahci mode. It will tell you that it will erase your data and so..., but nothing happens. All your data will be there and your write speed will be 150x better. 6.5 with AHCI does not work well. I got write performance of 2MB/sec... It was virtually impossible to use. I used 6.5 from Vmware though.

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