Date: Fri, 23 Nov 2007 10:11:59 +0300 From: Alexey Popov <lol@chistydom.ru> To: Kris Kennaway <kris@FreeBSD.org> Cc: freebsd-hackers@freebsd.org, Panagiotis Christias <christias@gmail.com>, freebsd-stable@freebsd.org Subject: Re: amrd disk performance drop after running under high load Message-ID: <47467D3F.7020002@chistydom.ru> In-Reply-To: <474492B0.1010108@FreeBSD.org> References: <47137D36.1020305@chistydom.ru> <47149E6E.9000500@chistydom.ru> <4715035D.2090802@FreeBSD.org> <4715C297.1020905@chistydom.ru> <4715C5D7.7060806@FreeBSD.org> <471EE4D9.5080307@chistydom.ru> <4723BF87.20302@FreeBSD.org> <47344E47.9050908@chistydom.ru> <47349A17.3080806@FreeBSD.org> <47373B43.9060406@chistydom.ru> <e4b0ecef0711111531k449f78fbnf7f3241b768498ad@mail.gmail.com> <4739557A.6090209@chistydom.ru> <4741EE9E.9050406@FreeBSD.org> <474492B0.1010108@FreeBSD.org>
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Kris Kennaway wrote: >>>> what is your RAID controller configuration (read ahead/cache/write >>>> policy)? I have seen weird/bogus numbers (~100% busy) reported by >>>> systat -v when read ahead was enabled on LSI/amr controllers. >>> I tried to run with disabled Read-ahead, but it didn't help. >> I just ran into this myself, and apparently it can be caused by >> "Patrol Reads" where the adapter periodically scans the disks to look >> for media errors. You can turn this off using -stopPR with the megarc gg >> port. > Oops, -disPR is the correct command to disable, -stopPR just halts a PR > event in progress. Wow! Really disabling Patrol Reads solves the problem. Thank you! I have many amrd's and all of them appear to have Patrol Reads enabled by default. But the problem happenes only on three of them. Is this a hardware problem? With best regards, Alexey Popov
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