Which of the following is not a file sharing service available on Linux systems
Choosing the file system that is appropriate for your application is an important decision due to the large number of options available and the trade-offs involved. This chapter describes some of the file systems that ship with Red Hat Enterprise Linux 9 and provides historical background and recommendations on the right file system to suit your application. Show
1.1. Types of file systemsRed Hat Enterprise Linux 9 supports a variety of file systems (FS). Different types of file systems solve different kinds of problems, and their usage is application specific. At the most general level, available file systems can be grouped into the following major types: Table 1.1. Types of file systems and their use cases
1.2. Local file systemsLocal file systems are file systems that run on a single, local server and are directly attached to storage. For example, a local file system is the only choice for internal SATA or SAS disks, and is used when your server has internal hardware RAID controllers with local drives. Local file systems are also the most common file systems used on SAN attached storage when the device exported on the SAN is not shared. All local file systems are POSIX-compliant and are fully compatible with all supported Red Hat Enterprise Linux releases. POSIX-compliant file systems provide support for a well-defined set of system calls, such as From the application programmer’s point of view, there are relatively few differences between local file systems. The most notable differences from a user’s perspective are related to scalability and performance. When considering a file system choice, consider how large the file system needs to be, what unique features it should have, and how it performs under your workload. Available local file systems
1.3. The XFS file systemXFS is a highly scalable, high-performance, robust, and mature 64-bit journaling file system that supports very large files and file systems on a single host. It is the default file system in Red Hat Enterprise Linux 9. XFS was originally developed in the early 1990s by SGI and has a long history of running on extremely large servers and storage arrays. The features of XFS include: Reliability
Performance characteristics XFS has a high performance on large systems with enterprise workloads. A large system is one with a relatively high number of CPUs, multiple HBAs, and connections to external disk arrays. XFS also performs well on smaller systems that have a multi-threaded, parallel I/O workload. XFS has a relatively low performance for single threaded, metadata-intensive workloads: for example, a workload that creates or deletes large numbers of small files in a single thread. 1.4. The ext4 file systemThe ext4 file system is the fourth generation of the ext file system family. It was the default file system in Red Hat Enterprise Linux 6. The ext4 driver can read and write to ext2 and ext3 file systems, but the ext4 file system format is not compatible with ext2 and ext3 drivers. ext4 adds several new and improved features, such as:
The extent-based metadata and the delayed allocation features provide a more compact and efficient way to track utilized space in a file system. These features improve file system performance and reduce the space consumed by metadata. Delayed allocation allows the file system to postpone selection of the permanent location for newly written user data until the data is flushed to disk. This enables higher performance since it can allow for larger, more contiguous allocations, allowing the file system to make decisions with much better information. File system repair time using the 1.5. Comparison of XFS and ext4XFS is the default file system in RHEL. This section compares the usage and features of XFS and ext4. Metadata error behavior In ext4, you can configure the behavior when the file system encounters metadata errors. The default behavior is to simply continue the operation. When XFS encounters an unrecoverable metadata error, it shuts down the file system and returns the In ext4, you can enable quotas when creating the file system or later on an existing file system. You can then configure the quota enforcement using a mount option. XFS quotas are not a remountable option. You must activate quotas on the initial mount. Running the The ext4 file system does not support more than 232 inodes. XFS dynamically allocates inodes. An XFS file system cannot run out of inodes as long as there is free space on the file system. Certain applications cannot properly handle inode numbers larger than 232 on an XFS file system. These applications might cause the failure
of 32-bit stat calls with the
If your application fails with large inode numbers, mount the XFS file system with the Do not use the 1.6. Choosing a local file systemTo choose a file system that meets your application requirements, you need to understand the target system on which you are going to deploy the file system. You can use the following questions to inform your decision:
If both your server and your storage device are large, XFS is the best choice. Even with smaller storage arrays, XFS performs very well when the average file sizes are large (for example, hundreds of megabytes in size). If your existing workload has performed well with ext4, staying with ext4 should provide you and your applications with a very familiar environment. The ext4 file system tends to perform better on systems that have limited I/O capability. It performs better on limited bandwidth (less than 200MB/s) and up to around 1000 IOPS capability. For anything with higher capability, XFS tends to be faster. XFS consumes about twice the CPU-per-metadata operation compared to ext4, so if you have a CPU-bound workload with little concurrency, then ext4 will be faster. In general, ext4 is better if an application uses a single read/write thread and small files, while XFS shines when an application uses multiple read/write threads and bigger files. You cannot shrink an XFS file system. If you need to be able to shrink the file system, consider using ext4, which supports offline shrinking. In general, Red Hat recommends that you use XFS unless you have a specific use case for ext4. You should also measure the performance of your specific application on your target server and storage system to make sure that you choose the appropriate type of file system. Table 1.2. Summary of local file system recommendations
1.7. Network file systemsNetwork file systems, also referred to as client/server file systems, enable client systems to access files that are stored on a shared server. This makes it possible for multiple users on multiple systems to share files and storage resources. Such file systems are built from one or more servers that export a set of file systems to one or more clients. The client nodes do not have access to the underlying block storage, but rather interact with the storage using a protocol that allows for better access control. Available network file systems
1.8. Shared storage file systemsShared storage file systems, sometimes referred to as cluster file systems, give each server in the cluster direct access to a shared block device over a local storage area network (SAN). Comparison with network file systems Like client/server file systems, shared storage file systems work on a set of servers that are all members of a cluster. Unlike NFS, however, no single server provides access to data or metadata to other members: each member of the cluster has direct access to the same storage device (the shared storage), and all cluster member nodes access the same set of files. Concurrency Cache coherency is key in a clustered file system to ensure data consistency and integrity. There must be a single version of all files in a cluster visible to all nodes within a cluster. The file system must prevent members of the cluster from updating the same storage block at the same time and causing data corruption. In order to do that, shared storage file systems use a cluster wide-locking mechanism to arbitrate access to the storage as a concurrency control mechanism. For example, before creating a new file or writing to a file that is opened on multiple servers, the file system component on the server must obtain the correct lock. The requirement of cluster file systems is to provide a highly available service like an Apache web server. Any member of the cluster will see a fully coherent view of the data stored in their shared disk file system, and all updates will be arbitrated correctly by the locking mechanisms. Performance characteristicsShared disk file systems do not always perform as well as local file systems running on the same system due to the computational cost of the locking overhead. Shared disk file systems perform well with workloads where each node writes almost exclusively to a particular set of files that are not shared with other nodes or where a set of files is shared in an almost exclusively read-only manner across a set of nodes. This results in a minimum of cross-node cache invalidation and can maximize performance. Setting up a shared disk file system is complex, and tuning an application to perform well on a shared disk file system can be challenging. Available shared storage file systems
Red Hat Enterprise Linux supports GFS2 on clusters that range in size from 2 to 16 nodes. 1.9. Choosing between network and shared storage file systemsWhen choosing between network and shared storage file systems, consider the following points:
Red Hat recommends that you use network file systems unless you have a specific use case for shared storage file systems. Use shared storage file systems primarily for deployments that need to provide high-availability services with minimum downtime and have stringent service-level requirements. 1.10. Volume-managing file systemsVolume-managing file systems integrate the entire storage stack for the purposes of simplicity and in-stack optimization. Available volume-managing file systems
Stratis was first released in Red Hat Enterprise Linux 8.0. It is conceived to fill the gap created when Red Hat deprecated Btrfs. Stratis 1.0 is an intuitive, command line-based volume manager that can perform significant storage management operations while hiding the complexity from the user:
Stratis offers powerful features, but currently lacks certain capabilities of other offerings that it might be compared to, such as Btrfs or ZFS. Most notably, it does not support CRCs with self healing. Which of the following can be used to graphically remotely administer a Linux machine?Which of the following can be used to graphically remotely administer a Linux machine? Correct. VNC is Virtual Network Computing and is a cross-platform method of graphically connecting to a remote system.
What are the three permissions used to control access to files and folders in Linux?read – The Read permission refers to a user's capability to read the contents of the file. write – The Write permissions refer to a user's capability to write or modify a file or directory. execute – The Execute permission affects a user's capability to execute a file or view the contents of a directory.
Which is a permission used to control access to files and folders in Linux quizlet?The three permissions used to control access to files and folders in Linux are: read, write, and delete. In regards to a user account, what does a white circle with a black arrow indicate? groups contain users from the domain in which they're created but can be assigned permissions to resources in other domains.
Which of the following are NTFS permissions choose three?There are three types of share permissions: Full Control, Change, and Read. Full Control: Enables users to “read,” “change,” as well as edit permissions and take ownership of files. Change: Change means that user can read/execute/write/delete folders/files within share.
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