Il 24-02-2018 23:07 Dave Chinner ha scritto:
Define "busy file", please.
Think about a running virtual machine. Maybe an XFS-based virtual image (ie: a CentOS 7 guest).
If the file is being actively written, then the clone will not be consistent. Yes, it's just like any other snapshot process - you have to quiesce everything that is writing to the file before cloning it. i.e. the data in the file needs to be in a stable, consistent, unchanging state if you want the clone to contain consistent data...
About *what* level of consistency are we speaking? I understand that application-level consistency requires a quiesced filesystem and, possibly, an application-level agent. But is it a quiesced filesystem a requisite for a *crash-consistent* ie: pull the plug) snapshot?
In other words: would a cp --reflink=always <vmdisk> <snapshot> of a runnig virtual machine produce an usable, crash-consistent snapshot, or it risks ending with binary garbage?
Thanks. -- Danti Gionatan Supporto Tecnico Assyoma S.r.l. - www.assyoma.it email: g.danti@xxxxxxxxxx - info@xxxxxxxxxx GPG public key ID: FF5F32A8 -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
