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Re: [Linux-cluster] Slow Start on Storage Access



isplist logicore net wrote:
Maybe I missed this in some of the other postings.

After I mount a GFS volume, there is always a delay when I first access the volume. I'm guessing somewhere between 30 seconds to 45 perhaps. This happens on first access and if the node has been idle for some time.

Is this because the node needs to do some calculations, get a fresh index or details about the storage, then it's fine?
Mike
Hi Mike,

The first access after a GFS mount will be understandably slower: It can take a long time to read in the resource group index and resource groups from disk. Once they're in memory, access to them will be fast. This should only happen after the mount.

It's a good question, so I added it to the FAQ.

After the system has been idle for a long time, the Linux VFS will force cached pages to disk and free up the memory. So in theory, it might take some time to re-read them
again.  Shouldn't be nearly as long as the first access after the mount.

Regards,

Bob Peterson
Red Hat Cluster Suite


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