Dell PowerMax Operate (DCA Operate) flashcards
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32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- PowerMax brick
- A 2U enclosure containing 25 NVMe SSDs and two node pair controllers. Bricks are the scaling unit for PowerMax capacity and performance.
- Engine
- A PowerMax enclosure containing two director boards in a redundant pair. Single-engine and two-engine arrays exist; two-engine arrays tolerate one engine failure.
- Thin device (TDev)
- A virtually provisioned device presented to a host with a defined size but consuming pool capacity only as data is written. Central to PowerMax capacity efficiency.
- Thin pool oversubscription
- The ratio of total subscribed thin device capacity to usable pool capacity. High ratios require monitoring of free space and growth rate.
- Storage group
- A logical container of devices presented together to a host. A storage group is bound to a port group and initiator group through a masking view.
- Masking view
- The binding of a storage group, port group, and initiator group that actually grants a host access to devices. Removing it removes host visibility.
- symaccess add dev
- Command used to add a device to a storage group: symaccess -sid SID -type storage -name SG add dev DEV. Verify with symaccess -check afterward.
- Port group
- A named set of front-end director ports used in a masking view. Hosts see devices through any port in the group unless an SPP restricts affinity.
- Initiator group
- A named set of host HBA WWNs or iSCSI IQNs. It is referenced by a masking view to identify which hosts may access the storage group.
- SPP in masking view
- Storage port to port mapping that optionally restricts which front-end ports a host uses. Without an SPP, any port in the port group can serve the host.
- Missing FC zone symptom
- A host cannot see a presented device even though the masking view is correct. The most common cause is a missing zone between the HBA and array port.
- Response time
- The primary performance SLO metric, measured in milliseconds. Rising response time at constant IOPS usually indicates queue buildup or backend contention.
- symstat command
- SYMCLI command that samples performance counters for devices, ports, pools, or RDF groups over an interval and count. Used for ad hoc performance checks.
- Front-end vs back-end bottleneck
- If front-end port busy is high while backend is low, the bottleneck is host or port. If backend is high, it is disk or pool contention.
- SRDF performance impact
- RDF traffic consumes port bandwidth and adds write latency on the R1 side. Monitor RDF port utilization and SRDF group lag during peak writes.
- TimeFinder SnapVX
- A point-in-time snapshot of a source device that is target-less until linked. Multiple generations per source are supported and addressed by name.
- symsnap link
- Command that links a snapVX snapshot to a target device so the target can be mounted and read. Unlink before terminating the snapshot.
- Snapshot pool consumption
- SnapVX uses copy-on-write, consuming pool capacity for changed tracks. Many retained generations can exhaust pool free space if unmonitored.
- TimeFinder Clone
- A full independent copy of a source device. It consumes full capacity and is decoupled from the source after creation, unlike a linked snapshot.
- SRDF/S
- Synchronous SRDF mode. The write is acknowledged to the host only after the R2 target commits it, so RTT directly affects host write latency.
- SRDF/A
- Asynchronous SRDF mode. The write is acknowledged at the R1 and replicated to R2 in cycles. Preferred when RTT is high.
- SRDF pair states
- Common states include Synchronized, Consistent, Suspended, Partitioned, Invalid, and Transitioning. Partitioned indicates the SRDF link is down.
- SRDF group
- A logical container pairing R1 source devices with R2 target devices on the remote array. Created and managed with symrdf commands.
- symcfg discover
- SYMCLI command that refreshes the local SYMAPI database with arrays visible to the management host. Run after adding or changing array connectivity.
- symconfigure commit
- SYMCLI pattern for configuration changes: symconfigure -sid SID -cmd "...;" commit -noprompt. The commit keyword applies the change.
- Unisphere REST API
- The PowerMax management API exposed under /univmax/rest/v1/. Used for automation of provisioning, performance, and capacity reporting with token auth.
- storevntd daemon
- The Solutions Enabler event daemon. Started with stordaemon start storevntd; displays and forwards array events to syslog or SNMP.
- Unisphere Health view
- Shows array health, component status for directors, bricks, ports, and power, plus active alerts. The first stop in any troubleshooting sequence.
- symdisk list
- SYMCLI command listing disk status and errors. symdisk show -disk N gives detail including sparing and error counts.
- Thin pool subscription ratio
- Subscribed capacity divided by usable pool capacity. A key capacity metric; rising ratio signals the need to add capacity or reclaim devices.
- Configured vs allocated capacity
- Configured capacity is the TDev size the host sees. Allocated capacity is what the device actually consumes in the thin pool.
- Data reduction ratio
- Logical capacity divided by physical capacity after compression and deduplication. Verify the reported ratio before assuming available headroom.