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Mapping volumes to an ESXi server
30 Dell EMC SC Series: Best Practices with VMware vSphere | 2060-M-BP-V
6.9.1.1 Setting round robin to be the default path selection policy
The round robin path selection policy (PSP) should be set to the default using the following command. After
creating the claim rule and rebooting, all SC Series volumes and protocol endpoints will acquire this policy.
esxcli storage nmp satp rule add -s VMW_SATP_ALUA -V COMPELNT -P VMW_PSP_RR -o
disable_action_OnRetryErrors -e "Dell EMC SC Series Claim Rule" -O
"policy=iops;iops=3"
Caution: With ESXi 6.7 and later, VMware has set the default SATP option for action_OnRetryErrors from
off to on, which may cause premature APD events during storage controller failover scenarios. See VMware
KB article 67006 for more information.
Caution: Host profiles may overwrite these claim rule options. In addition, the round robin path selection
policy may be unsupported for use with Microsoft Clustering Services depending on the version of ESXi.
Check the current support status.
6.9.1.2 Conditions for path changes
When using the round robin path selection policy, the native multipathing plug-in (NMP) has custom
properties that can be tuned to optimize traffic flow between each of the paths. By default, the round robin
PSP will switch paths every 1,000 I/Os or 10 MB, whichever comes first. Dell internal lab testing has shown
that modifying the IOPS value can have a noticeable performance impact based on the I/O patterns. Because
the optimum tuning value for each datastore depends on the data patterns issued by the guests, thorough
testing is recommended to prevent negative performance. When beginning testing, a good starting point is to
set the IOPS to 3 as shown in the following.
To set the values for a datastore, use the following steps:
1. Find the datastore device NAA identifier.
~ # esxcli storage nmp device list
naa.6000d31000ed1f000000000000000179
Device Display Name: COMPELNT Fibre Channel Disk
(naa.6000d31000ed1f000000000000000179)
Storage Array Type: VMW_SATP_ALUA
Storage Array Type Device Config: {implicit_support=on;
explicit_support=off; explicit_allow=on; alua_followover=on;
action_OnRetryErrors=on;
{TPG_id=61475,TPG_state=AO}{TPG_id=61479,TPG_state=AO}{TPG_id=61476,TPG_st
ate=AO}{TPG_id=61480,TPG_state=AO}}
Path Selection Policy: VMW_PSP_FIXED
Path Selection Policy Device Config:
{preferred=vmhba3:C0:T6:L120;current=vmhba3:C0:T6:L120}
Path Selection Policy Device Custom Config:
Working Paths: vmhba3:C0:T6:L120
Is USB: false
2. If not set previously, modify the disk device to use the round robin PSP.