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). ZP.
2010/2/8 Zavodsky, Daniel (GE Capital) <[email protected]> > 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:* [email protected] [mailto: > [email protected]] *On Behalf Of *Zoran Popović > *Sent:* Thursday, February 04, 2010 1:40 AM > *To:* Red Hat Enterprise Linux 5 (Tikanga) discussion mailing-list; > [email protected] > *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. > > _______________________________________________ > rhelv5-list mailing list > [email protected] > https://www.redhat.com/mailman/listinfo/rhelv5-list > >
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