On Mon, Feb 08, 2010 at 04:46:59PM +0100, Zoran Popovi? wrote:
> Tell me what would you like to know more about my environment - I was
> trying to give all relevant information, at least concerning this issue.
> And, btw, echo 1 > /proc/sys/vm/drop_caches does the work I have needed
> - if I do this I get results I need (and, for example, if I don't do that
> after snapshot restore on the storage, my HVM Windows guest usually start
> chkdsk during boot).
So you're saying you need drop_caches *with* phy for the other host to see the
disk contents?
-- Pasi
> ZP.
>
> 2010/2/8 Zavodsky, Daniel (GE Capital) <[1]daniel.zavodsky@xxxxxx>
>
> Hello,
> I have tried this and it works here... caching is not used for phy:
> devices, only buffering but it is flushed frequently so it is not a
> problem. Maybe you should post some more info about your setup?
>
> Regards,
> Daniel
>
> --------------------------------------------------------------------------
>
> From: [2]rhelv5-list-bounces@xxxxxxxxxx
> [mailto:[3]rhelv5-list-bounces@xxxxxxxxxx] On Behalf Of Zoran Popoviæ
> Sent: Thursday, February 04, 2010 1:40 AM
> To: Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list;
> [4]xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: [rhelv5-list] shared storage manual remount ...
> I am wondering if there is a way to solve the following problem: I
> suppose that the usual way is to establish distributed file system with
> locking mechanisms like it is possible with GFS and Red Hat Cluster
> Suite or similar, but I am interested in doing some of this manually and
> ONLY with raw devices (no file system), or simply in knowing some
> general principles. The case: I have a VLUN (on FC SAN) presented on two
> servers, but mounted only on one host - to be more precise, used by a
> Xen HVM guest system as a raw physical phy:// drive. Then, I put this
> guest down, and bring it manually up on second host - it can see changed
> images, and make changes to the presented disks. Then I put it down
> there, and bring it up again on the first host - BUT THEN, this guest
> (or host) doesn't see changes made by the second system, it still sees
> the picture as it was the way it left it.
> Or even better, if I bring HVM guest on a host, then put it down, make
> restore of his disks on the storage (I am using HP EVA8400, restoring
> original disk from a snapshot - it does have redundant controllers but
> their cache must be in sync for sure), and then bring it up - it still
> sees things on the disks as they were before restore. But if I _RESTART_
> the host, it can see restored disks correctly. Now, I am wondering why
> is this happening, and if it is possible somehow to resync with the
> storage without restart (I wouldn't like that on production ! and on our
> windows systems this is possible) ... I've tried sync (but that is like
> flushing buffer cache), and I didn't try echo 3 >
> /proc/sys/vm/drop_caches after that (I've just come upon some articles
> about that), and I am not sure if that would really invalidate cache and
> help me. What is the right way of dong this ? Please, help ...
> ZP.
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> References
>
> Visible links
> 1. mailto:daniel.zavodsky@xxxxxx
> 2. mailto:rhelv5-list-bounces@xxxxxxxxxx
> 3. mailto:rhelv5-list-bounces@xxxxxxxxxx
> 4. mailto:xen-users@xxxxxxxxxxxxxxxxxxx
> 5. mailto:rhelv5-list@xxxxxxxxxx
> 6. https://www.redhat.com/mailman/listinfo/rhelv5-list
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