Slow iscsi performance on ESXi 6.7.0.
setup 1:-
1) Created a new LUN from ISCSI storage(500 GB) and presented to ESXi hosts.Created a new ISCSI data store and provided 200 GB storage to Windows 2016 OS.
When we are testing the file copy between C to D,we are seeing the transfer rate is below 10 mbps/sec.It starts at 200mbps/sec and going down to below 10 mbps/sec.
setup 2:-
2) When we are passing the direct ISCSI LUN(as a RDM) to Win 2012 OS,we see the transfer rate is more than 1 gbps/sec.
I dont know where is the problem. I like to test the below option to see the performance.
1) First,we need to change the RAID controller in to write cache(enabled) i.e BBRC. If possible,we can insert HBA card to test this.---->Not tested yet.
2) Can be tested by enabling Jumbo frames from Network to Standalone ESXi server/storage server.---->Not tested yet.
3) Can create a new subnet for ISCSI(dedicated) and then can be checked with dedicated NICS.---->Not tested yet.
4) Can change one VM to vmxnet3 and another machine to E1000 and then can be tested.---->Tested but no luck
5) Can change one VMDK to lazy zeroed/eager zeroed and then can be tested---->Tested but no luck
6) Create a new SCSI controller with "Para Virtualization" and then test the performance---->Tested but no luck
Note:- Right now I have 2*10 G NICS for VSAN network.ISCSI also using through the same VSAN network.
Any other suggestions?
Thanks,
Manivel RR
Hi André,
Thanks Andre.This is testing environment only.There is an improvement after disabling delayed ack.
Can we change RAID controller to BBRU(write cache enable) or swap with HBA(storage server)? Also can test with enabling Jumbo frames.
Its going between 60 to 100 mp/sec now.
What type/model of iSCSI storage do you use? Did you check the storage vendor's best practices for setup with ESXi?
This is not an enterprise SAN and we are testing the ISCSI with Linux XFS file system(Supermicro server)
How does the network (iSCSI VMkernel port goups) setup for the iSCSI look like?
2 * 10 GB NICS already present to VSAN network with active/passive mode(DV switch).ISCSI traffic also using the same VSAN network and their NICS.
We are going to test with anew 2* 10 G NICS(not VSAN NICS) to check the performance.
Several iSCSI storage systems require that e.g. DelayedACK is disabled (see https://kb.vmware.com/s/article/1002598). This can make a huge difference.
Yes.Tested it.Slight improvement are there.
Jumbo frames may also make a difference - especially in 10gbps networks - but I don't think that this is causing the current slowness.
As I said earlier,this option is not tested yet.
Also I changed the ESXi IO restrictions from 128 to 512 k today.
To increase io size to maximum:
esxcli system settings advanced set -o /ISCSI/MaxIoSizeKB -i 512
vmkernel logs
Thank you,
Manivel RR