FreeNAS 9.10 iSCSI + ESXi 5.5 - Write Performance Issues

[jgreco]

Dude, you are just slow. :)

I just type a lot more than you.

 

[depasseg]

I just type a lot more than you.

That is true.

 

[cyberjock]

Having said that, do these numbers look good? Again, we're talking about an idle volume. Clearly the numbers that are 200+ MB/sec are great, because we're talking about 2GB Ethernet backbone. So it can't get get any faster. The 4K Q32T1 write speeds are slower, and the 4K write speeds are really slower, but in comparison to my windows storage server boxes, these are actually flying. Is this what is normally to be expected?

Yeah, don't let the benchmarks fool you. I've seen quite a few people that chose RAIDZ2 for VMs because "the benchmarks told me so" and later found out they really screwed themselves. Benchmarks don't tell you everything. Parallel IO is the problem with running VMs, and benchmarks don't demonstrate parallel IO very well. ;)

 

[jgreco]

Yeah, don't let the benchmarks fool you. I've seen quite a few people that chose RAIDZ2 for VMs because "the benchmarks told me so" and later found out they really screwed themselves. Benchmarks don't tell you everything. Parallel IO is the problem with running VMs, and benchmarks don't demonstrate parallel IO very well. ;)

That's a problem I've been fighting basically all my professional life. I remember talking with some RAID manufacturer in the early 2000's who could not understand why their 16K/32K/64KB stripe size wasn't making my client happy, and I basically had to draw pictures for them that showed if you're retrieving a 1MB chunk of a Usenet article from an array that had a 64K stripe size, this meant that you were forcing 16 of the 24 drives in the array to do a seek. They had a real rough time getting their head around the fact that we weren't looking for MBytes/sec performance but rather IOPS/sec performance. We needed to be able to retrieve lots of stuff in parallel without causing undue dependencies between drives. In the end we ended up building a 24-drive-in-4U solution here in shop and making what was essentially a Usenet storage appliance. Fun days.

 

[titan_rw]

Dude, you are just slow. :)


VMware IOanalyzer is great for this.
https://labs.vmware.com/flings/io-analyzer

Strange, but this link is already 404. "Page not found" according to vmware.com

 

[depasseg]

Google vmware fling ioanalyzer

I'm on my phone right now.

 

[jgreco]

Google vmware fling ioanalyzer

I'm on my phone right now.

 

[depasseg]

Huh, that's weird. I thought maybe I pasted the wrong URL, but it's a 404 for me too. I visited that page when I posted the original link. I've got a copy of the OVA if the page doesn't come back soon.

 

[titan_rw]

Google vmware fling ioanalyzer

I'm on my phone right now.

I assume you're joking.

I did google it. The first hit is to the URL you provided. It 404's. That's why I posted.

 

[depasseg]

I assume you're joking.

I did google it. The first hit is to the URL you provided. It 404's. That's why I posted.

No, sorry, I meant that I thought I borked the URL when I pasted it. And I didn't have access to it on my phone.

 

[jgreco]

Seems like it is there now.

 

[titan_rw]

Seems like it is there now.

Ahh, yes. Seems vmware fixed it.

Downloading now.