Dell PowerVault MD3000i - Manual (Page 30)

Dell™ PowerVault MD3000 and MD3000i Array Tuning Best Practices
December 2008 – Revision A01 Page 30
Appendix D: Glossary of Terms
Term Definition
Burstiness
A data traffic property defined as the ratio of the peak
I/O rate to the average I/O rate; in this case, the mean
duty cycle exhibited by I/O transmitted or received from
a storage array. Burstiness is adopted from its
common usage in describing network workloads.
Controller Saturation
Controller saturation is where an individual RAID
Controller Module is reached a maximum operational
load and is unable to perform additional operations
within its available bandwidth. Additional operations
above this maximum point are not lost, they are instead
queued up transitionally. This is considered an
inflection point where performance hits a hard ceiling.
GiB Gibibyte; see kibibyte.
HBA
Host Bus Adapter
HDD Hard Disk Drive
Interposer
Integrated circuit with an interface routing between two
opposing signaling sides. Used in the
MD3000/MD3000i to interface SATA HDDs to the SAS
backplane to perform translation.
iSCSI
Internet Small Computer Systems Interface. The iSCSI
protocol is defined by the IETF in RFC 3720.
KiB
See Kibibyte.
Kibibyte Kilo binary byte; IEC SI unit to separately denote 1024
or 2
10 bytes (base-2) distinctly from the base-10
kilobyte (10 3 or 1000 bytes). See IEC/ISO ISO 80000,
IEC 60027-2, or IEEE 1541-2002.
Long I/O Any I/O burst that exceeds 1/3 of the available cache
memory size with an increased chance of not being
wholly handled in cache.
MD3000
Dell™ PowerVault MD3000 Expandable Storage Array
with SAS front-end.
MD3000i
Dell™ PowerVault MD3000i Expandable Storage Array
with iSCSI front-end.
MDSM
Dell™ Modular Disk Storage Manager. Host
management utility suite for configuring and
maintaining a MD3000/MD3000i storage array.
MiB
Mebibyte, see kibibyte.
NIC Network Interface Controller
NL-SAS
Near-line SAS; A hybrid technology of larger capacity
SATA HDDs with a special SAS controller board