Title :
Modelling and Validation of Response Times in Zoned RAID
Author :
Lebrecht, Abigail S. ; Dingle, Nicholas J. ; Knottenbelt, William J.
Author_Institution :
Dept. of Comput., Imperial Coll. London, London
Abstract :
We present and validate an enhanced analytical queueing network model of zoned RAID. The model focuses on RAID levels 01 and 5, and yields the distribution of I/O request response time. Whereas our previous work could only support arrival streams of I/O requests of the same type, the model presented here supports heterogeneous streams with a mixture of read and write requests. This improved realism is made possible through multiclass extentions to our existing model. When combined with priority queueing, this development also enables more accurate modelling of the way subtasks of RAID 5 write requests are scheduled. In all cases we derive analytical results for calculating not only the mean but also higher moments and the full distribution of I/O request response time. We validate our model against measurements from a real RAID system.
Keywords :
RAID; queueing theory; I/O requests; analytical queueing network model; response time validation; zoned RAID system; Analytical models; Computer networks; Data storage systems; Delay; Disk drives; Educational institutions; Modems; Performance analysis; Queueing analysis; Storage area networks;
Conference_Titel :
Modeling, Analysis and Simulation of Computers and Telecommunication Systems, 2008. MASCOTS 2008. IEEE International Symposium on
Conference_Location :
Baltimore, MD
Print_ISBN :
978-1-4244-2817-5
Electronic_ISBN :
1526-7539
DOI :
10.1109/MASCOT.2008.4770572
