Date: Mon, 24 May 2010 08:59:26 +0300 From: Nikos Vassiliadis <nvass9573@gmx.com> To: Eitan Adler <lists@eitanadler.com> Cc: crwhipp@gmail.com, freebsd-questions@freebsd.org Subject: Re: File system Message-ID: <4BFA15BE.1060607@gmx.com> In-Reply-To: <AANLkTikRnq1nHtfXp0f73WjX8Qzp-bcEdoEhKkISzff6@mail.gmail.com> References: <u2z768631271005081836k26590481qcaab03601799448d@mail.gmail.com> <4BE84825.9060005@gmx.com> <1a7012fe7affe8caf4263d4d2c385614.squirrel@whipp.no-ip.org> <4BF10F3D.2070207@gmx.com> <AANLkTikRnq1nHtfXp0f73WjX8Qzp-bcEdoEhKkISzff6@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Eitan Adler wrote: > gjournal will replay all write attempts >> (metadata and data) before the failure, so you should be relatively >> sure that all writes are done correctly. > > As I understand it journals work by writing to disk a log of all the > changes that have to be made - waits for confirmation that it wrote > the data - and then attempts to make those changes. If after the > confirmation there is a crash the log file is replayed. > Certain virtual machines will report to the OS that it wrote the data > to disk before it actually does so. In that case journaling doesn't > actually help as the log file is still not on some form of stable > storage. I am not an expert on the subject, I thought the journal will replay all logged write attempts and since the number of all write attempts logged in the journal will be much bigger than the number of requests a cache can hold you will be sure that all writes will be done on the filesystem. Again, I am not an expert on the subject... Nikos
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?4BFA15BE.1060607>