When GPFS was first developed, RAID storage was not commonplace. To protect data, a file system could be configured so that each piece of data could be have a replica written to a second location. Over time, this mechanism was extended so that data could also be written to a third location. Functionally, there is … Continue reading Failure groups in Spectrum Scale
All disks in Spectrum Scale have a few pieces of information at fixed positions: Sector 1 is the "File System unique ID". This will be matched in the file system descriptor to a Spectrum Scale disk name, and is written to the disk when it is added to the file system with mmcrfs, mmadddisk, or … Continue reading File System Descriptor Quorum in Spectrum Scale
Spectrum Scale systems are organized into clusters. File systems and underlying resources are owned by clusters, managed by clusters, and possibly exported to remote clusters. Within a cluster, there is a need for certain management functions. Because we would like the cluster to remain active even in the face of systems or network links failing, … Continue reading Cluster quorum and Spectrum Scale
Many factors go into determining the performance of a storage system, and a common question is: What will be the performance of this storage system? Ultimately, actual performance can only be determined through benchmarking with the actual workloads, but this isn't always possible when planning to acquire a storage system. We need a way to … Continue reading Modeling disk performance (traditional RAID)
There are a few ways to install Spectrum Scale on a cluster. Since version 4.1.1, when Spectrum Scale introduced protocol nodes, the software bundle has included a toolkit to help with installation. Over time, this toolkit has improved considerably -- but it takes a bit of finessing to get an environment ready for the toolkit. … Continue reading Manually installing Spectrum Scale software on Red Hat
POSIX is the Portable Operating System Interface standard, IEEE Std 1003.1-1988 and related. These standards, based on the Unix operating system, define a set of programming and command interfaces. Programs and scripts following these standards are supposed to be easily portable between operating system platforms providing these interfaces. The POSIX standards imply a model for file system … Continue reading POSIX file system basics
Storage systems organize data in several common ways, and we need to be clear with our terminology. This is particularly important for people who have worked with only one type of organization! Traditionally, IT storage is what we would call "block storage". Technical and desktop computing generally works with "file storage". Web and cloud-based applications … Continue reading Block, File, and Object Storage
Storage and computing are the two most important components of information technology, just as nouns and verbs are the most essential components of language.