- Native Multipathing
- Storage Array Type Plug-in (SATP)
- Path Selection Plugin (PSP)
- Third-Party Plug-ins
- Multipathing Plugins (MPPs)
- Anatomy of PSA Components
- I/O Flow Through PSA and NMP
- Listing Multipath Details
- Claim Rules
- MP Claim Rules
- Plug-in Registration
- SATP Claim Rules
- Modifying PSA Plug-in Configurations Using the UI
- Modifying PSA Plug-ins Using the CLI
- Summary
This chapter is from the book
This chapter is from the book
This chapter is from the book
SATP Claim Rules
Now that you understand how NMP plugs into PSA, it’s time to examine how SATP plugs into NMP.
Each SATP is associated with a default PSP. The defaults can be overridden using SATP claim rules. Before I show you how to list these rules, first review the default settings.
The command used to list the default PSP assignment to each SATP is
esxcli storage nmp satp list
The output of this command is shown in Figure 5.28.
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Figure 5.28. Listing SATPs and their default PSPs
The name space is Storage, NMP, and finally SATP.
Knowing which PSP is the default policy for which SATP is half the story. NMP needs to know which SATP it will use with which storage device. This is done via SATP claim rules that associate a given SATP with a storage device based on matches to Vendor, Model, Driver, and/or Transport.
To list the SATP rule, run the following:
esxcli storage nmp satp rule list
The output of the command is too long and too wide to capture in one screenshot. I have divided the output to a set of images in which I list a partial output then list the text of the full output in a subsequent table. Figures 5.29, 5.30, 5.31, and 5.32 show the four quadrants of the output.
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Figure 5.29. Listing SATP claim rules—top-left quadrant of output.
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Figure 5.30. Listing SATP claim rules—top-right quadrant of output.
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Figure 5.31. Listing SATP claim rules—bottom-left quadrant of output
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Figure 5.32. Listing SATP claim rules—bottom-right quadrant of output
To make things a bit clearer, let’s take a couple of lines from the output and explain what they mean.
Figure 5.33 shows the relevant rules for CLARiiON arrays both non-ALUA and ALUA capable. I removed three blank columns (Driver, Transport, and Options) to fit the content on the lines.
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Figure 5.33. CLARiiON Non-ALUA and ALUA Rules
The two lines show the claim rules for EMC CLARiiON CX family. Using this rule, NMP identifies the array as CLARiiON CX when the Vendor string is DGC. If NMP stopped at this, it would have used VMW_SATP_CX as the SATP for this array. However, this family of arrays can support more than one configuration. That is the reason the value Claim Options column comes in handy! So, if that option is tpgs_off, NMP uses the VMW_SATP_CX plug-in, and if the option is tpgs_on, NMP uses VMW_SATP_ALUA_CX. I explain what these options mean in Chapter 6.
Figure 5.34 shows another example that utilizes additional options. I removed the Device column to fit the content to the display.
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Figure 5.34. Claim rule that uses Claim Options
In this example, NMP uses VMW_SATP_DEFAULT_AA SATP with all arrays returning HITACHI as a model string. However, the default PSP is selected based on the values listed in the Claim Options column:
- If the column is blank, the default PSP (which is VMW_PSP_FIXED and is based on the list shown earlier in this section in Figure 5.28) is used. In that list, you see that VMW_SATP_DEFAULT_AA is assigned the default PSP named VMW_PSP_FIXED.
- If the column shows inq_data[128]={0x44 0x46 0x30 0x30}, which is part of the data reported from the array via the Inquiry String, NMP overrides the default PSP configuration and uses VMW_PSP_RR instead.