>But you look around, you may find that many >systems claim that they can take snapshot without shutdown the >application. The claim is true, because you can just pause the application and not shut it down. While this means you can't simply add snapshot capability and solve your copy consistency problem (you need new applications too), this is a huge advance over what there was before. Without snapshots, you do have to shut down the application. Often for hours, and during that time any service request to the application fails. With snapshots, you simply pause the application for a few seconds. During that time it delays processing of service requests, but every request ultimately goes through, with the requester probably not noticing any difference. If a system claims that snapshot function in the filesystem alone gets you consistent backups, it's wrong. -- Bryan Henderson IBM Almaden Research Center San Jose CA Filesystems - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
