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Gleb Chesnokov
9bdffe6fe6
The iSER and distribution guides prescribe OFED 1.5 installation,
deleting packaged RDMA modules, patching kernel builds and applying
host-wide tuning. The Gentoo procedure targets SVN, while the bundled
OCF agents are neither built nor exercised by repository CI.
Commit 025574018e ("isert: Support building against MOFED without
patching the kernel build system") established the supported
header-selection model. Current Makefile conftests and isert-scst
sources define the remaining compatibility and transport limits.
Replace fixed OFED and tuning recipes with those sources and matching
vendor guidance. Reduce the Gentoo and resource-agent documents to
historical integration notes, and spell out their module, sysfs,
daemon, session and storage side effects before any reuse.
58 lines
2.3 KiB
Plaintext
58 lines
2.3 KiB
Plaintext
iSCSI extensions for RDMA driver
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================================
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Overview
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--------
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isert-scst provides the iSER transport for the iSCSI-SCST target. Target,
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authentication, LUN, and access-control configuration uses the same interfaces
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described in README. The iscsi-scst Makefile builds isert-scst when the selected
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kernel build tree enables InfiniBand support.
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For the repository build and installation workflow, see ../INSTALL.md. For the
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external RDMA header selection implemented by the iscsi-scst Makefile, see
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README.iser_ofed.
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Configuration
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-------------
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There is no separate iSER target type. Use allowed_portal attributes when a
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target must be restricted to particular RDMA-capable addresses; see README for
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the current syntax and matching rules.
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The read-only isert_nr_devs module parameter controls the pool of concurrent
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connection requests handled during login. The source default is 128 and values
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greater than 999 are rejected. This limit does not restrict the number of
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established connections.
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Performance
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-----------
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QueuedCommands defaults to 32 and its effective maximum is limited by the
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registered kernel component. Do not assume that 128 is accepted or optimal;
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measure the intended workload before changing it.
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NUMA locality between backing storage, memory, CPUs, and the RDMA adapter can
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affect performance. Use current kernel and adapter-vendor guidance for
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system-wide RDMA, IRQ, IOMMU, and network tuning.
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Limitations
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-----------
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* Bidirectional SCSI commands are not supported by isert-scst.
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Troubleshooting
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---------------
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* Confirm that the selected KDIR has InfiniBand enabled and check the build
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output for the RDMA header flavor selected by the iscsi-scst Makefile.
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* With an external OFED or MOFED stack, ensure that its development headers and
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Module.symvers match the RDMA modules for the target kernel. See
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README.iser_ofed.
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* For discovery across selected interfaces, verify the target's allowed_portal
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attributes and the addresses returned to the initiator.
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* For connection or latency problems, first verify RDMA connectivity, routing,
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source-address selection, device placement, and kernel logs. Do not apply
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global arp_ignore, persistent device-naming, or iommu=pt changes from an old
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deployment without validating them for the current host.
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