Technical Knowledge Base

SP - Storage Processor – provides access to all external hosts and the file side of VNX.
SP A - Storage processor A – Generic term for the first storage processor in VNX for block.
SP B - Storage processor B – Generic term for the second storage processor in VNX for block.
SPE - Storage Processor Enclosure.
DAE - Disk Array Enclosure.
DPE - Disk and Processor Enclosure, containing both storage processors and disk drives.
DME - Data Mover Enclosure – includes one or two Data Movers.
DM - Data Mover – enclosure component (X-Blade) running VNX Operating Environment for File.
VDM - Virtual Data Mover – File software feature that enables users to administratively separate CIFS servers, replicate CIFS environments, and move CIFS servers from one Data Mover to another.
FE - Frond End – communication ports from the hosts to the SP.
BE - Back End – ports connecting the SP to the back-end bus(es) and drives.
CRU - Customer-replaceable unit – a hardware component that can be replaced as an entire unit.
FRU - Field-replaceable unit – a hardware component that can be replaced as an entire unit.
SLIC - Small I/O Card – containined within SP or DM. SLIC options include 10GbE, Fibre Channel, iSCSI, SAS.
SAS - Serial Attached SCSI – A point-to-point serial protocol for moving data to drives. A higher speed serial version of SCSI.
NL-SAS - Near-Line SAS drives have the highest capacity and the lowest speed (7200 RPM)
EFD - Enterprise Flash Drive – a semiconductor-based storage device. Highest performing storage device.
SPS - Standby Power Supply – battery system used to provide power to VNX for block during a power outage.
LCC - Link Control Card – cards used in the DAE for connectivity to SP or another DAE on the BE.
DART - Data Access in Real Time – the operating system software that runs on the Data Mover.
FLARE - Fibre Logic Array Runtime Environment – block side operating system.
Gatekeeper - Logical disk used as a buffer between VNX for file and the Symmetrix system for the exchange of management commands and data.
FLU - FLARE LUN – traditional Raid Group LUN.
PFS - Production File System – built on Symmetrix volumes or VNX for Block LUNs and mounted on a Data Mover in the VNX for File.
Cache - Memory used by the storage system to buffer read and write data and to insulate the host from drive access times.
Cache hit - When a host sends read or write operations directly to cache.
Cache miss - When data requested by the host is not found in the cache, resulting in a disk request.
Dirty Page - A cache page not yet written to disk.
Write-aside - Bypass of the write cache with the write immediately sent to the disks.
Write-aside size - The largest IO size that can be written to cache. Any IO larger goes straight to disk.
Reason Code - A code which represents the state of Control Stations and Data Movers.
SnapSure - On the VNX for file, a feature that provides read-only, point-in-time copies, also known as checkpoints, of a file system.
SnapSure SavVol - The volume to which SnapSure copies original point-in-time data blocks from the Production File System (PFS) before the blocks are altered by a transaction. SnapSure uses the contents of the SavVol and the unchanged PFS blocks to maintain a checkpoint of the PFS.
TLU - Thin Provisioned LUN.
Voyager - 60 Drive (3.5”) SAS Enclosure supports SAS and SATA.
Viper - 15 Drive (3.5”) SAS Enclosure supports SAS and SATA.
Derringer - 25 Drive (2.5”) SAS Enclosure supports SAS and SATA.
VIA - VNX Installation Assistant – A client-based GUI interface used to pre-configure a freshly installed VNX and run a system health check at time of installation.
Vault - Reserved area on disks for system files and cache dumps.
DLU - Direct LUN – also known as a VP Pool Thick LUN.
FAST - Fully Automated Storage Tiering.
FAST Cache - Secondary I/O cache composed of Flash drives.
Flush - Writing the data in the write cache to the drives.
Throughput — IOPS - Input/output operations per second.
Large-block - I/O operations with capacities greater than 64 KB.
MirrorView - Data replication software.
Analyzer - Performance analysis software.
NDU - Non-disruptive update – Upgrading system software while applications are running with minimal effect on the application performance.
Prefetch - A caching method by which some number of blocks beyond the current read request are read and cached in the expectation of future use.
Rebuild - The reconstruction of a failed drive’s data through either parity or mirroring.
Sector - The smallest addressable unit on a hard drive; a sector contains 512 bytes of data.
Short stroking - A LUN performance optimization technique of only using a portion of a RAID group.
Trespass - A multipathing host-initiated change in SP LUN ownership as a result of a failure or command.
Unisphere - Web administrative tool for FLARE revisions 30.0 and later.
DUMP - A quick copy of the cache image to vault disks (fault protection).
Forced Flush - Flush due to incoming write not having an empty page to write to (not optimized but fastest method of flushing to data drives).
Watermarks - Low and high watermarks are set to avoid forced flushes while maximizing write cache hits.
SnapView - A point-in-time copy application.
Snapshot - Backup copy of how a LUN looks at a particular point in time.
Stripe - Distributing sequential chunks of storage across many drives in a RAID group.
USM - Unisphere Service Manager – is a desktop application that is used to upgrade, install and maintain the hardware and software of a storage system.
Coalesce - Grouping together multiple smaller I/O’s into one larger I/O.