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Movements, leaders, victories and the continuing fight for equality.
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Explore the people, places, events, achievements, struggles and stories that shaped our journey.
Movements, leaders, victories and the continuing fight for equality.
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Pioneers, champions, Negro Leagues, records, activism and excellence.
Meet the people whose lives, choices and achievements shaped the journey.
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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| Developer | Oracle Corporation |
|---|---|
| Full name | Oracle Cluster file System |
| Introduced | March 2006 with Linux 2.6.16 |
| Limits | |
| Max volume size | 4 PB (OCFS2)[1] |
| Max file size | 4 PB (OCFS2)[1] |
| Max filename length | 255 bytes |
| Allowed filename characters | All bytes except NUL and '/' |
| Features | |
| Dates recorded | modification (mtime), attribute modification (ctime), access (atime) |
| File system permissions | Unix permissions, ACLs and arbitrary security attributes (Linux 2.6 and later) |
| Transparent compression | No |
| Transparent encryption | No |
| Data deduplication | No |
| Copy-on-write | Yes |
| Other | |
| Supported operating systems | Linux |
The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared-disk file system developed by Oracle Corporation and released under the GNU General Public License. The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included.
OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" (Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas.[2][3]
OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler.[4] Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink.[5]
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
A distributed lock manager (DLM) runs in every machine in a cluster, with an identical copy of a cluster-wide lock database. Operating systems use lock managers to organise and serialise the access to resources. In this way a DLM provides software applications which are distributed across a cluster on multiple machines with a means to synchronize their accesses to shared resources. DLMs have been used as the foundation for several successful clustered file systems, in which the machines in a cluster can use each other's storage via a unified file system, with significant advantages for performance and availability. The main performance benefit comes from solving the problem of disk cache coherency between participating computers. The DLM is used not only for file locking but also for coordination of all disk access. VMScluster, the first clustering system to come into widespread use, relied on the OpenVMS DLM in just this way.
Distributed concurrency control is the concurrency control of a system distributed over a computer network (Bernstein et al. 1987, Weikum and Vossen 2001). In database systems and transaction processing (transaction management) distributed concurrency control refers primarily to the concurrency control of a distributed database. It also refers to the concurrency control in a multidatabase (and other multi-transactional object) environment (e.g., federated database, grid computing, and cloud computing environments. A major goal for distributed concurrency control is distributed serializability (or global serializability for multidatabase systems). Distributed concurrency control poses special challenges beyond centralized one, primarily due to communication and computer latency. It often requires special techniques, like distributed lock manager over fast computer networks with low latency, like switched fabric (e.g., InfiniBand). The most common distributed concurrency control technique is strong strict two-phase locking (SS2PL, also named rigorousness), which is also a common centralized concurrency control technique. SS2PL provides both the serializability and strictness. Strictness, a special case of recoverability, is utilized for effective recovery from failure. For large-scale distribution and complex transactions, distributed locking's typical heavy performance penalty (due to delays, latency) can be saved by using the atomic commitment protocol, which is needed in a distributed database for (distributed) transactions' atomicity.
In computing, the Global File System 2 (GFS2) is a shared-disk file system for Linux computer clusters. GFS2 allows all members of a cluster to have direct concurrent access to the same shared block storage, in contrast to distributed file systems which distribute data throughout the cluster. GFS2 can also be used as a local file system on a single computer. GFS2 has no disconnected operating-mode, and no client or server roles. All nodes in a GFS2 cluster function as peers. Using GFS2 in a cluster requires hardware to allow access to the shared storage, and a lock manager to control access to the storage. The lock manager operates as a separate module: thus GFS2 can use the distributed lock manager (DLM) for cluster configurations and the "nolock" lock manager for local filesystems. Older versions of GFS also support GULM, a server-based lock manager which implements redundancy via failover. GFS and GFS2 are free software, distributed under the terms of the GNU General Public License.
The Oracle Cluster File System (OCFS, in its second version OCFS2) is a shared-disk file system developed by Oracle Corporation and released under the GNU General Public License. The first version of OCFS was developed with the main focus to accommodate Oracle's database management system that used cluster computing. Because of that it was not a POSIX-compliant file system. With version 2 the POSIX features were included. OCFS2 (version 2) was integrated into the version 2.6.16 of Linux kernel. Initially, it was marked as "experimental" (Alpha-test) code. This restriction was removed in Linux version 2.6.19. With kernel version 2.6.29 in late 2008, more features were included into ocfs2, such as access control lists and quotas. OCFS2 used a distributed lock manager which resembles the OpenVMS DLM but is much simpler. Oracle announced version 1.6 in November 2010 which included a copy on write feature called reflink.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Mae Jemison, aboard Space Shuttle Endeavour in 1992.
