Helps if I send this to the list...<br><br><div class="gmail_quote">---------- Forwarded message ----------<br>From: <b class="gmail_sendername">Nathan Cerny</b> <span dir="ltr"><<a href="mailto:ncerny@gmail.com">ncerny@gmail.com</a>></span><br>
Date: Mon, Apr 4, 2011 at 4:54 PM<br>Subject: Re: [DRBD-user] DRBD primary/primary vs. VMFS3 ?<br>To: pberton <<a href="mailto:pascal.berton3@free.fr">pascal.berton3@free.fr</a>><br><br><br>You have to run Protocol C to do primary/primary. Protocol C ensures both nodes know of each block write before it's reported as complete. So in your instance, one VM would get the block, and another would get a different block. There is no chance of them both reserving the same block.<div>
<br></div><div>At least that's how I understand Protocol C. I'm sure someone else will correct me if I'm mistaken!</div><div><br></div><div><div><div></div><div class="h5"><br><br><div class="gmail_quote">On Mon, Apr 4, 2011 at 11:33 AM, pberton <span dir="ltr"><<a href="mailto:pascal.berton3@free.fr" target="_blank">pascal.berton3@free.fr</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><br>
Hi folks!<br>
I've read a few posts talking about DRBD vs. VMFS3, but none seem to answer<br>
my question. May be someone can help. Here's the picture :<br>
I'm thinking of a primary/primary config, with ESXs on both sides. If hosted<br>
VMs do snapshots or make use of thin disks on both sides, corresponding<br>
files will grow step by step or should I say, block by block, each new block<br>
allocation being securized using SCSI reservations from the host running<br>
that VM.<br>
Now, guess 2 VMs on different sides of the replication chain make a new<br>
block request at the same time. What would happen ? I suppose SCSI<br>
reservations are not replicated by DRBD, therefore, each host will make its<br>
own reservation and potentially allow the same block to both VMs leading to<br>
corruption ?<br>
Has anyone already played with this kind of architecture ? Is<br>
primary/primary definitely a no-no for such architectures or is there some<br>
magic feature that can help me out build something safe ?<br>
Thanks by advance!<br>
Best regards,<br>
Pascal.<br>
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</font></blockquote></div><br><br clear="all"><br></div></div>-- <br>Nathan Cerny<br><br>-------------------------------------------------------------------------------<div><div>"I have always wished that my computer would be as easy to use as my telephone. My wish has come true. I no longer know how to use my telephone."</div>
<div>--Bjarne Stroustrup, Danish computer scientist</div>-------------------------------------------------------------------------------</div><br>
</div>
</div><br><br clear="all"><br>-- <br>Nathan Cerny<br><br>-------------------------------------------------------------------------------<div><div>"I have always wished that my computer would be as easy to use as my telephone. My wish has come true. I no longer know how to use my telephone."</div>
<div>--Bjarne Stroustrup, Danish computer scientist</div>-------------------------------------------------------------------------------</div><br>