Guidelines for Solstice DiskSuite Software

Consider the following points when you plan Solstice DiskSuite configurations.

• Local metadevice names - Each local metadevice name must be unique throughout the cluster and cannot be the same as any device ID (DID) name.

• Mediators - Each diskset configured with exactly two disk strings and mastered by exactly two nodes must have Solstice DiskSuite mediators configured for the diskset. A disk string consists of a disk enclosure, its physical disks, cables from the enclosure to the node(s), and the interface adapter cards. You must configure each diskset with exactly two nodes acting as mediator hosts. You must use the same two nodes for all disksets requiring mediators and those two nodes must master those disksets. Mediators cannot be configured for disksets that do not meet the two-string and two-host requirements. See the mediator(7) man page for details.

• /kernel/drv/md.conf settings - All metadevices used by each diskset are created in advance, at reconfiguration boot time, based on configuration parameters found in the /kernel/drv/md.conf file. The fields in the md.conf file are described in the Solstice DiskSuite documentation. You must modify the nmd and md_nsets fields as follows to support a Sun Cluster configuration.

  • nmd - The nmd field defines the number of metadevices created for each diskset. You must set the value of nmd to the predicted largest number of metadevices used by any one of the disksets in the cluster. For example, if a cluster uses 10 metadevices in its first 15 disksets, but 1000 metadevices in the 16th diskset, you must set the value of nmd to at least 1000. Also, the value of nmd must be large enough to ensure that there are enough numbers for each DID name and each local metadevice name to be unique throughout the cluster. The maximum number of metadevices allowed per diskset is 8192. The default number of metadevices per diskset is 128.

  • md_nsets - The md_nsets field defines the total number of disksets that can be created for a system to meet the needs of the entire cluster. You must set the value of md_nsets to the expected number of disksets in the cluster, plus one to allow Solstice DiskSuite software to manage the private disks on the local host (that is, those metadevices that are not in the local diskset). The maximum number of disksets allowed per cluster is 32. The default number of disksets is 4.

  Set these fields at installation time to allow for all predicted future expansion of the cluster. Increasing these values after the cluster is in production is time consuming because it requires a reconfiguration reboot for each node. Raising these values later also increases the possibility of inadequate space allocation in the root (/) file system to create all of the requested devices.

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  Caution -

  All cluster nodes must have identical /kernel/drv/md.conf files, regardless of the number of disksets served by each node. Failure to follow this guideline can result in serious Solstice DiskSuite errors and possible loss of data.

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