From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-ID: <4009A583.7070007@lig.net> From: "Stephen D. Williams" MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="------------030206040508010004010806" Subject: [uml-devel] Dynamic remount with variable COW stacking/merging needed, support for snapshot repilication Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Sat, 17 Jan 2004 16:13:39 -0500 To: user-mode-linux-devel@lists.sourceforge.net, user-mode-linux-user@lists.sourceforge.net This is a multi-part message in MIME format. --------------030206040508010004010806 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit When a UML instance is running a always-on service, such as a web server, an administrator needs to be able to make live backups, or replications, of a running system. This can be done using LVM snapshots, although that is not always appropriate for just this feature. A UML instance can be paused and then restarted, but this can cause severe delays while large partitions are replicated. The COW ability is a great basis for an ideal solution, but I believe we need to identify and implement some additional features. What I propose as a useful solution is: A UML instance mounts filesystems directly or based on a COW image. When an administrator invokes a console snapshot mode, the UML instance causes a quick freeze, new delta COWs to be created and stacked on existing mounts, then resumes. When the administrator completes whatever snapshot backup is needed, they invoke a console unsnapshot command which pauses the instance, merges the delta COWs, remounts the original images with updates, and resumes. This relies on COW stacking, which I saw was added in a patch last year and I assume is still present. The downtime for the instance would be measured in seconds generally. Can this be done now? What needs to be added to support it? sdw -- swilliams@hpti.com http://www.hpti.com Personal: sdw@lig.net http://sdw.st Stephen D. Williams 703-724-0118W 703-995-0407Fax 20147-4622 AIM: sdw --------------030206040508010004010806 Content-Type: text/x-vcard; charset=utf8; name="sdw.vcf" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="sdw.vcf" begin:vcard fn:Stephen Williams n:Williams;Stephen email;internet:sdw@lig.net tel;work:703-724-0118 tel;fax:703-995-0407 tel;pager:sdwpage@lig.net tel;home:703-729-5405 tel;cell:703-371-9362 x-mozilla-html:TRUE version:2.1 end:vcard --------------030206040508010004010806-- ------------------------------------------------------- The SF.Net email is sponsored by EclipseCon 2004 Premiere Conference on Open Tools Development and Integration See the breadth of Eclipse activity. February 3-5 in Anaheim, CA. http://www.eclipsecon.org/osdn _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel