Journaling accelerates the recovery time after an unexpected shutdown, significantly improving the availability of server and storage systems. This process can take hours on a multi-terabyte volume, resulting in an unacceptable period of server downtime. Before the server can restart and resume services, it must perform a consistency check that requires going through the entire file system, block by block. In an unjournaled file system, drives are in an unknown state after a failure, meaning that there is no record of their activity just prior to the shutdown. Always remember to back up your data as frequently as necessary.Ī power outage or system failure interrupts read and write processes, which can cause discrepancies between the file system directory and the actual location and structure of stored files. In addition, restarting the computer is much faster. If the server fails in the middle of an operation, the file system can "replay" the information in its log and complete the operation when the server restarts.Īlthough you may experience loss of user data that was buffered at the time of the failure, the file system is returned to a consistent state. With journaling turned on, the file system logs transactions as they occur. If your computer stops because of a power failure or some other issue, the journal is used to restore the disk to a known-good state when the server restarts. When you enable journaling on a disk, a continuous record of changes to files on the disk is maintained in the journal. It both prevents a disk from getting into an inconsistent state and expedites disk repair if the server fails. Journaling is a technique that helps protect the integrity of the Mac OS Extended file systems on Mac OS X volumes. It also helps to maximize the uptime of servers and connected storage devices by expediting repairs to the affected volumes when the system restarts. Journaling protects the integrity of the file system on Xserve and other computers using Mac OS X Server in the event of an unplanned shutdown or power failure. Journaling for the Mac OS Extended (HFS Plus) file system enhances computer availability and fault resilience, which is especially noteworthy for servers. This document explains some of the benefits of using this feature and how it works. Journaling was first introduced in Mac OS X Server 10.2.2, then to the non-server OS in Mac OS X 10.3 Panther. "Journaling" is a feature that helps protect the file system against power outages or hardware component failures, reducing the need for repairs. I can't say that by having it enabled it saved the day for a failed drive but I also haven't had much need to find out in real life I know on a few files servers here we turned it on/off to see if there as any noticeable speed difference - non detected. Your fine not using journaling - more of a OSX server feature to help salvage crashed systems.
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