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<DIV><FONT size=2 face=Arial>@Dietmar or anyone that can answer:</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Note:<BR>These questions is because I am involved
in a project and the idea is to use several RAID 10 in the same PVE Host for use
of a VM, and for the backup a single SATA hard drive will be used on an NFS
Server</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Question 1:<BR>Then, if the backup code don't use
buffers for write cache, and my Storage of NFS Server Backup is very slow
compared to my storage of Virtualization, when the VM need to write to his
Virtual Disk, the behavior will be sync write to both disks (to the Storage of
NFS Server Backup and to Virtual Disk of the VM)?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Reasoning:<BR>Because if the answer is positive,
for my understand we have slow writes within the same VM while "KVM Live Backup"
is running because will write synchronously to both two disks (to the
Storage of NFS Server Backup and to Virtual Disk of the VM).</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Question 2:<BR>If the answer of the question1 is
negative. ie "KVM Live Backup" don't sync the writes to both disks, how works
"KVM Live Backup" in this case?</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>Best regards<BR>Cesar</FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT></DIV>
<DIV><FONT size=2 face=Arial></FONT> </DIV>
<DIV><FONT size=2 face=Arial>----- Original Message ----- </FONT>
<DIV><FONT size=2 face=Arial>From: "Dietmar Maurer" <</FONT><A
href="mailto:dietmar@proxmox.com"><FONT size=2
face=Arial>dietmar@proxmox.com</FONT></A><FONT size=2
face=Arial>></FONT></DIV>
<DIV><FONT size=2 face=Arial>To: "Alessandro Briosi" <</FONT><A
href="mailto:ab1@metalit.com"><FONT size=2
face=Arial>ab1@metalit.com</FONT></A><FONT size=2 face=Arial>>; "Cesar
Peschiera" <</FONT><A href="mailto:brain@click.com.py"><FONT size=2
face=Arial>brain@click.com.py</FONT></A><FONT size=2 face=Arial>>;
<</FONT><A href="mailto:pve-devel@pve.proxmox.com"><FONT size=2
face=Arial>pve-devel@pve.proxmox.com</FONT></A><FONT size=2
face=Arial>></FONT></DIV>
<DIV><FONT size=2 face=Arial>Sent: Tuesday, January 28, 2014 6:05
AM</FONT></DIV>
<DIV><FONT size=2 face=Arial>Subject: RE: [pve-devel] KVM Live Backup
performance</FONT></DIV></DIV>
<DIV><FONT face=Arial><BR><FONT size=2></FONT></FONT></DIV><FONT size=2
face=Arial>> He is complaining that the new code enables write cache during
backup.<BR>> If there's a VM which is running a database in an HA scenario,
and for some<BR>> reasons the VM/host crashes during the backup, the database
would be<BR>> inconsistent when started on another host, cause of the write
cache.<BR><BR>AFAIK the backup code does not change caching behavior in any
way.<BR><BR></FONT></BODY></HTML>