I/O stutter on hughes

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There's been some intermittent problems with IO on hughes. This was happening only when we were zeroing the data on newly allocated logical volumes from the host server.

We had kernel error messages such as

Mar 15 22:04:05 hughes kernel: PCI-DMA: Out of SW-IOMMU space for 65536 bytes at device 0000:03:00.0

This symptom is the same as

http://blog.prgmr.com/xenophilia/2013/05/holmes-crash-due-to-out-of-sw-.html

but fortunately has not caused a system crash. 

We have not seen this problem with I/O on hughes at any other time. At the time of the next system reboot we will take the opportunity to put in a larger value for swiotlb. If we observe this under normal conditions rather than unusually heavy load we will schedule a reboot within a few hours after that.

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This page contains a single entry by srn published on March 15, 2015 11:38 PM.

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