Live migration of virtual hard disks between storage arrays has long been possible. However, there is a dearth of online tools to perform automated virtual disk placement and IO load balancing across multiple storage arrays. This problem is quite challenging because the performance of IO workloads depends heavily on their own characteristics and that of the underlying storage device. Moreover, ...

Aims: The hard and soft spectral states of black hole accretion are understood as connected with ADAF accretion (truncated disk) and standard disk accretion, respectively. However, observations indicate the existence of cool gas in the inner region at times when the disk is already truncated outside. We try to shed light on these not yet understood intermediate states. Methods: The disk-corona ...

The traditional virtual machine building and and deployment process is centered around the virtual machine hard disk image. The packages comprising the VM operating system are carefully selected, hard disk images are built for a variety of different hypervisors, and images have to be distributed and decompressed in order to instantiate a virtual machine. Within the HEP community, the CernVM Fil...

High-end solid state disks (SSDs) provide much faster access to data compared to conventional hard disk drives. We present a technique for using solid-state storage as a caching layer between RAM and hard disks in database management systems. By caching data that is accessed frequently, disk I/O is reduced. For random I/O, the potential performance gains are particularly significant. Our system...

We review radiative processes responsible for X-ray emission in hard (low) and soft (high) spectral states of black-hole binaries. The main process in the hard state appears to be scattering of blackbody photons from a cold disk by thermal electrons in a hot inner flow, and any contribution from nonthermal synchrotron emission is at most small. In the soft states, blackbody disk emission domina...

A multitude of different hard disk power management algorithms exists—applied to real systems or proposed in the literature. Energy savings can only be achieved if the hard disk is idle for a minimum period of time. These algorithms try to predict the length of each idle interval at runtime and decide whether the disk should be switched to a lowpower mode or not. In this paper, we claim that th...

Hard disk drives are becoming increasingly vulnerable to security attacks as they are now accessed remotely, attached to mobile devices or used in other previously unanticipated operating environments. Protecting data while at rest has emerged as a chief concern for storage vendors who have introduced secure disks in the market. These devices are capable of encrypting data on the fly before rec...

The hard disk drive is probably the predominant form of storage media and is a primary data source in a forensic investigation. The majority of available software tools and literature relating to the investigation of the structure and content contained within a hard disk drive concerns the extraction and analysis of evidence from the various file systems which can reside in the user accessible ...

I review here some of the open questions regarding the geometry and emission mechanisms of galactic black hole candidates. For hard states, I concentrate on the perspective of “disk+Compton coronae” models (for discussions of jet models, see the papers by Sera Markoff). Specifically, I discuss the implications from our 10 year long RXTE monitoring campaign of Cyg X-1. I then present simultaneou...

Abstract We study the spectral evolution of black hole candidate EXO 1846−031 during its 2019 outburst, in 1–150 keV band, with Hard X-ray Modulation Telescope. The continuum spectrum is well modeled an absorbed disk-blackbody plus cutoff power law, hard, intermediate, and soft states. In addition, we detect ≈6.6 Fe emission line hard intermediate state. Throughout states, fitted inner disk rad...