LVM in the Linux environment: performance examination

Ovaj članak predstavlja ocjenjivanje svojstava LVM (Logical Volume Manager) sustava pod Linux operativnim sustavom. Rad uključuje matematički model vremena pristupa datotečnom sustavu sa i bez LVM opcije. Matematički model je validiran na primjeru Linux 32bit ext3, na kernel verziji 2.6, a na bazi usporedbe svojstava datotečnog sustava konfiguriranog za dva slučaja, sa i bez LVM. Mi smo generirali dvije LVM mogućnosti, istog kapaciteta, ali različite po složenosti unutarnje strukture. Svojstva su mjerena pomoću Postmark benchmark aplikacije koja simulira opterećenje Internet e-mail servera. Definirali smo tri vrste opterećenja, pri čemu uglavnom dominiraju relativno mali objekti. Rezultati ispitivanja su pokazali da je najbolja opcija da se koristi datotečni sustav bez primjene LVM. Benchmark rezultati su tumačeni na temelju matematičkog modela vrijemena pristupa datotečkom sustavu.This paper presents a performance evaluation of LVM (Logical Volume Manager) system under the Linux operating system. The presented work includes proposal of the mathematical modeling of file system access time with and without LVM option. A mathematical model is further validated for the case of 32bit Linux ext3 file system with kernel version 2.6, taking into consideration the comparison of a file system in two defined configurations, with and without LVM. We have created two LVM options, with the same capacity, but different in complexity of the internal structure. The performance is measured using the Postmark benchmarking software application that simulates workload of Internet mail server. We have defined three types of workloads, generally dominated by relatively small objects. Test results have shown that the best option is to use direct file system realization without applying LVM. Benchmark results are interpreted based on provided mathematical model of file system access time

Parallel netCDF: A Scientific High-Performance I/O Interface

Dataset storage, exchange, and access play a critical role in scientific applications. For such purposes netCDF serves as a portable and efficient file format and programming interface, which is popular in numerous scientific application domains. However, the original interface does not provide an efficient mechanism for parallel data storage and access. In this work, we present a new parallel interface for writing and reading netCDF datasets. This interface is derived with minimum changes from the serial netCDF interface but defines semantics for parallel access and is tailored for high performance. The underlying parallel I/O is achieved through MPI-IO, allowing for dramatic performance gains through the use of collective I/O optimizations. We compare the implementation strategies with HDF5 and analyze both. Our tests indicate programming convenience and significant I/O performance improvement with this parallel netCDF interface.Comment: 10 pages,7 figure