Date: Wed, 10 Oct 2001 10:24:37 +0200 From: Hanno Liem <freebsd@dark4ce.com> To: Martin Vana <martin.vana@vslib.cz> Cc: freebsd-newbies@freebsd.org Subject: Re: need to clarify some terms Message-ID: <20011010102437.B30118@dark4ce.com> In-Reply-To: <000701c15162$b2ba8e60$1198e693@kolej.vslib.cz>; from martin.vana@vslib.cz on Wed, Oct 10, 2001 at 10:08:08AM %2B0200 References: <000701c15162$b2ba8e60$1198e693@kolej.vslib.cz>
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My shot at explaining - any additions/comments welcome :-) On Wed, Oct 10, 2001 at 10:08:08AM +0200, Martin Vana wrote: > can anyone tell me what is Q.O.S. Quality of Service. I've mostly heard it used in a network environment, where it means that different applications/users/protocols have different 'levels' of service. For instance, a packet containing a telephone conversation arriving in time is more important than a download in progress, so the first type of packet should have priority over the second one. > Soft Updates FreeBSD implementation of a journalling file system > Journaling Assuming you mean "journalling file system" here, in the context of the last word. File systems contain data and meta-data. The data are the contents of your files, the meta-data are things like date, file name, but also where on the disk parts (clusters) of the file are stored. In a working environment, 10s or 100s or 1000s of files are opened, closed, modified, written, created etc. at the same time. The OS takes care that the meta-data is updated and reflects the current state of the file system. In the event of a crash, it is possible that meta-data has not been written to disk yet, resulting in an inconsistent file system. Data could get lost this way: for example, the 'content' of a file has been written to disk, but the metadata (location where the file is stored on the disk) hasn't. A journalling file system keeps a 'logfile' of all activities in the file system. Then, when 'half' an operation has been executed, the system can just 'roll back' to a previous state. > MFC (probably verb) ? Microsoft Foundation Classes ? (eludes me at the moment, not so MS minded these days) Han To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-newbies" in the body of the message
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