Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
On Thu, May 10, 2007 at 10:44:58AM +0100, Mark Watts wrote: > > > Hi all: > > > > I have no idea about how long the primary sync its data to secondary? > > > > Or once the data is changed on primary physical device, it is send to > > secondary immediately? > > Data replication is basically real-time, within the constraints of network > bandwidth and raw I/O performance. > > In the "resource" section of /etc/drbd.conf, you define the transfer protocol > to use for that resource (/dev/drbd0 for example). > > It can be one of the following three: > > C: write IO is reported as completed, if we know it has > reached _both_ local and remote DISK. > * for critical transactional data. * for most cases. > > B: write IO is reported as completed, if it has reached > local DISK and remote buffer cache. * for cases were you can live with possible data loss of the last few milliseconds in case of failover we should improve our documented recommendations :) > A: write IO is reported as completed, if it has reached > local DISK and local tcp send buffer. (see also sndbuf-size) > * for high latency networks > > If you choose C, then write a file to the DRBD'd filesystem, > the write won't and then fsync! otherwise the write goes just into the local nodes cache, and drbd knows nothing about it yet... > return (ie: the command won't complete) until the data is written to both > local and remote disks. > > Mark. > > -- > Mark Watts BSc RHCE MBCS > Senior Systems Engineer > QinetiQ Trusted Information Management > Trusted Solutions and Services Group > GPG Key: http://keyserver.veridis.com:11371/search?q=0x455420ED > _______________________________________________ > drbd-user mailing list > drbd-user at lists.linbit.com > http://lists.linbit.com/mailman/listinfo/drbd-user -- : Lars Ellenberg Tel +43-1-8178292-0 : : LINBIT Information Technologies GmbH Fax +43-1-8178292-82 : : Vivenotgasse 48, A-1120 Vienna/Europe http://www.linbit.com : __ please use the "List-Reply" function of your email client.