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Altecice

Low I/O performance with ESXi 6.0

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Altecice

The b120i driver uses system RAM for caching. Somebody mentioned that the b120i ESXi driver doesn't allocate much cache. I've not tested it myself.

 

I am using AHCI mode in the BIOS, bypassing the B120i.

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saq

If you have AHCI mode set in the BIOS you should see disk-level performance in ESXi 6. I had a Vertex3 in my system for a while on Port0 on the B120i 8087 port and I was maxing out the disk at pretty high numbers. 90k ish sequential IOPS, 400MB/s+. Not quite as fast as my LSI 9211-8i (IBM M1015) but good enough. If I had the B120i in RAID mode, even at RAID0, the performance was very poor. 15-20MB/s poor.

 

The B120i in RAID mode is a very poor performer in ESXi because it is a "fake-raid" controller that offloads all of the processing and RAM onto the operating system and uses the system CPU to drive disk operations. ESXi has a very thin amount of resources it allows to be used towards server resources, preferring as much of the cpu/ram cycles to go towards virtual machine activity as possible, which is how the people who pay lots of money for ESXi want it.

 

If you could, screenshot your storage adapters tab under configuration and select the port that has your SSD on it. That might help answer a few things.

Edited by saq

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Altecice

If you could, screenshot your storage adapters tab under configuration and select the port that has your SSD on it. That might help answer a few things.

 

Sorry I dont quite get what you mean. Do you mean data stores in ESXi? or in the BIOS.

 

Yes I have moved from using fake raids to ACHI mode and I noticed a speed improvement. It just still seems to be an issue with writing to the server as reading is good.

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Altecice

Right its drive related I think.

 

I had a random old Laptop 5400rpm drive and plugged it into ESXi as a data store and shared it with my 2012 R2 vm.

As far as I am aware 'Modified' RAM is data that's cached into RAM awaiting to be written to disk, once it reaches around 1.6gb of 4gb of RAM on 2012 R2 the transfer slows massively.

 

So I did a bit of testing, I moved a 20gb ISO to my faster 1Tb 7200RPM. the Modified actually kept its self under then 1.6gb limit so the transfer was full 1Gbit (100-110mb/s).

I then tried the same thing but to the slower 5400rpm laptop drive and I noticed the modified increasing very quickly and hit its 1.6gb limit very quickly and throttle the download.

 

So do you think its safe to come to the conclusion that drive write speed is a factor here? Perhaps getting a quicker drive like a WD RED would improve/solve my issues?.

I guess increasing RAM allowance to the VM would solve the issue as well.

Edited by Altecice

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ikon

WD Red drives aren't that much faster.

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GotNoTime

WD Red drives aren't that much faster.

Yup. The WD Reds are basically the low power WD Greens but with modified firmware. They say that they're balanced better as well to reduce vibration but that really just means they're a bit more careful at the factory. The firmware changes are mainly to do with enabling TLER so your entire drive doesn't drop out if there is a problem and setting power management to not automatically spindown the drive.

 

They're only certified for small NAS boxes with up to 5 drives as they don't compensate for vibration unlike the much more expensive enterprise drives.

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Altecice

WD Red drives aren't that much faster.

 

 

Yup. The WD Reds are basically the low power WD Greens but with modified firmware. They say that they're balanced better as well to reduce vibration but that really just means they're a bit more careful at the factory. The firmware changes are mainly to do with enabling TLER so your entire drive doesn't drop out if there is a problem and setting power management to not automatically spindown the drive.

 

They're only certified for small NAS boxes with up to 5 drives as they don't compensate for vibration unlike the much more expensive enterprise drives.

 

 

Ahhh I see!. Well I guess its something i am going to have to live with. Most of my NAS will be smaller files and more downloading from the 2012 server to my desktop anyway.

 

Can you reccomend me any HHD's anyway as I want to replace them with larger disks. cost/performance wise I mean.

 

Thansk everyone for the help!.

Edited by Altecice

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schoondoggy

Right its drive related I think.

 

I had a random old Laptop 5400rpm drive and plugged it into ESXi as a data store and shared it with my 2012 R2 vm.

As far as I am aware 'Modified' RAM is data that's cached into RAM awaiting to be written to disk, once it reaches around 1.6gb of 4gb of RAM on 2012 R2 the transfer slows massively.

 

So I did a bit of testing, I moved a 20gb ISO to my faster 1Tb 7200RPM. the Modified actually kept its self under then 1.6gb limit so the transfer was full 1Gbit (100-110mb/s).

I then tried the same thing but to the slower 5400rpm laptop drive and I noticed the modified increasing very quickly and hit its 1.6gb limit very quickly and throttle the download.

 

So do you think its safe to come to the conclusion that drive write speed is a factor here? Perhaps getting a quicker drive like a WD RED would improve/solve my issues?.

I guess increasing RAM allowance to the VM would solve the issue as well.

Just curious, what is the model number of the laptop drive you were using?

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ikon

Yup. The WD Reds are basically the low power WD Greens but with modified firmware. They say that they're balanced better as well to reduce vibration but that really just means they're a bit more careful at the factory. The firmware changes are mainly to do with enabling TLER so your entire drive doesn't drop out if there is a problem and setting power management to not automatically spindown the drive.

 

They're only certified for small NAS boxes with up to 5 drives as they don't compensate for vibration unlike the much more expensive enterprise drives.

 

I disagree about the vibration compensation in Red drives. WD specifically say that Red drives incorporate dynamic vibration dampening. I watched a video about it where it showed active counter balancers in the drives. I don't recall where I saw the video, but I'll see if I can find a link.

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Altecice

What is the model number of the laptop drive you were using?

 

Laptop drive - Toshiba MK5076GSX 500gb

Other Desktop Drive - Seagate ST3500418AS 500GB  (the one that can just keep 1gbit speeed for the Iso)

Edited by Altecice

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