UNCLASSIFIED It could be a buffering issue. You could try adjusting the Buffer to Buffer (BB) credits on the qlogic switches. I know brocade use 16, perhaps the qlogics are different/higher?
Another thought is that perhaps the lun is not on the preferred controller. And access now goes across the backplane (ALUA) of the array. Double check that the lun is on the preferred controller for the primary path that you are using for backups. It may have moved when the switches were replaced. Greg. -----Original Message----- From: tech-boun...@lists.lopsa.org [mailto:tech-boun...@lists.lopsa.org] On Behalf Of Edward Ned Harvey (lopser) Sent: Monday, 10 February 2014 11:47 PM To: Michael Ryder Cc: LOPSA Technical Discussions Subject: Re: [lopsa-tech] Fibre-Channel Performance issue > From: Michael Ryder [mailto:mryder1...@gmail.com] > Sent: Sunday, February 9, 2014 10:48 PM > > Yes, it's enterprise -- a pair of HP EVA arrays. We're talking to > them via 4Gb fibre-channel. Single-initiator zones. There's a > combination of RAID levels going on on the arrays.... but it all used to > perform so *well*. > The connection goes like this > EVA --> > (4Gb FC) --> > Windows Backup Proxy Server --> > (1Gb Eth, TCP port 1500) --> > Windows Backup Server (TSM) What kind of performance does the Proxy server get, performing IO directly to the EVA, just simply reading/writing disk as fast as possible? It sounds to me, like your new switches are buffering data, and delaying the "data has been flushed" signal. Which would be good for most things, and in fact, which I would call "broken" because the proper behavior would be to correctly deliver the signal when requested. As you said, the "correct" fix for such a problem would be a driver/firmware upgrade. But anyway - Counterintuitively, you might benefit by *disabling* write-back and/or buffering. This is analogous to a surprising finding I had in ZFS: You actually *hurt* zfs performance, if you have a pool of HDD's and SSD's in the backend, with HBA write-back enabled. Performance is improved by disabling the write-back (Unless your pool is purely a bunch of HDD's, in which case, the write-back helps.) _______________________________________________ Tech mailing list Tech@lists.lopsa.org https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/ IMPORTANT: This email remains the property of the Department of Defence and is subject to the jurisdiction of section 70 of the Crimes Act 1914. If you have received this email in error, you are requested to contact the sender and delete the email. _______________________________________________ Tech mailing list Tech@lists.lopsa.org https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
