Date: Mon, 16 Feb 2015 01:07:12 -0800 From: zx zx <zhangxia3@hotmail.com> To: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: About Filesystem freeze/thaw in freebsd Message-ID: <COL128-W74C2CE6B8243E74B26A286F62E0@phx.gbl>
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Hi=2C I am experimenting to do a live backup of FreeBSD VM. = Question is do we have freeze/thaw interfaces in FreeBSD? I searched a lot = in web and freebsd source code=2C just could not find the right interface. = As I know that in linux:VxFS provides ioctl interfaces to app= lication programs to freeze and thaw VxFS file systems. The interfaces are = VX_FREEZE=2C VX_FREEZE_ALL=2C and VX_THAW.About Freeze and thaw Freezing a = file system temporarily blocks all I/O operations to a file system and then= performs a sync on the file system. Current operations are completed and t= he file system is synchronized to disk. Freezing a file system is a necessa= ry step for obtaining a stable and consistent image of the file system at t= he volume level. Consistent volume-level file system images can be obtained= and used with a file system snapshot tool. The freeze operation flushes al= l buffers and pages in the file system cache that contain dirty metadata an= d user data. The operation then suspends any new activity on the file syste= m until the file system is thawed. Any help would be appreciate= d=2C thanks a lot! Andy Zhang =
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