From owner-freebsd-stable@freebsd.org Fri May 3 13:08:00 2019 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id C27DA1590121 for ; Fri, 3 May 2019 13:07:59 +0000 (UTC) (envelope-from michelle@sorbs.net) Received: from hades.sorbs.net (hades.sorbs.net [72.12.213.40]) by mx1.freebsd.org (Postfix) with ESMTP id 1CC8B70C35 for ; Fri, 3 May 2019 13:07:57 +0000 (UTC) (envelope-from michelle@sorbs.net) MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Received: from [10.10.0.230] (gate.mhix.org [203.206.128.220]) by hades.sorbs.net (Oracle Communications Messaging Server 7.0.5.29.0 64bit (built Jul 9 2013)) with ESMTPSA id <0PQX00G6ZJSEYO20@hades.sorbs.net> for freebsd-stable@freebsd.org; Fri, 03 May 2019 06:21:53 -0700 (PDT) Subject: Re: ZFS... From: Michelle Sullivan X-Mailer: iPad Mail (16A404) In-reply-to: <20190503125118.GA11226@neutralgood.org> Date: Fri, 03 May 2019 23:07:51 +1000 Cc: freebsd-stable@freebsd.org, Borja Marcos , Pete French Content-transfer-encoding: quoted-printable Message-id: <2A7B5457-371A-4014-8C1E-972BA2FD10DF@sorbs.net> References: <3d0f6436-f3d7-6fee-ed81-a24d44223f2f@netfence.it> <17B373DA-4AFC-4D25-B776-0D0DED98B320@sorbs.net> <70fac2fe3f23f85dd442d93ffea368e1@ultra-secure.de> <70C87D93-D1F9-458E-9723-19F9777E6F12@sorbs.net> <58DA896C-5312-47BC-8887-7680941A9AF2@sarenet.es> <62803130-9C40-4A98-B5A4-A2DFAC0FAD65@sorbs.net> <20190503125118.GA11226@neutralgood.org> To: "Kevin P. Neal" X-Rspamd-Queue-Id: 1CC8B70C35 X-Spamd-Bar: --- Authentication-Results: mx1.freebsd.org; spf=pass (mx1.freebsd.org: domain of michelle@sorbs.net designates 72.12.213.40 as permitted sender) smtp.mailfrom=michelle@sorbs.net X-Spamd-Result: default: False [-3.07 / 15.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; NEURAL_HAM_MEDIUM(-0.98)[-0.977,0]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; R_SPF_ALLOW(-0.20)[+a:hades.sorbs.net]; NEURAL_HAM_LONG(-1.00)[-0.999,0]; MIME_GOOD(-0.10)[text/plain]; DMARC_NA(0.00)[sorbs.net]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_SOME(0.00)[]; MX_GOOD(-0.01)[cached: battlestar.sorbs.net]; NEURAL_HAM_SHORT(-0.91)[-0.908,0]; RCVD_IN_DNSWL_NONE(0.00)[40.213.12.72.list.dnswl.org : 127.0.10.0]; SUBJ_ALL_CAPS(0.45)[6]; IP_SCORE(-0.42)[ip: (-1.07), ipnet: 72.12.192.0/19(-0.55), asn: 11114(-0.43), country: US(-0.06)]; RCVD_NO_TLS_LAST(0.10)[]; FROM_EQ_ENVFROM(0.00)[]; R_DKIM_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; ASN(0.00)[asn:11114, ipnet:72.12.192.0/19, country:US]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2] X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 03 May 2019 13:08:00 -0000 Michelle Sullivan http://www.mhix.org/ Sent from my iPad > On 03 May 2019, at 22:51, Kevin P. Neal wrote: >=20 > On Fri, May 03, 2019 at 08:25:08PM +1000, Michelle Sullivan wrote: >>> On 03 May 2019, at 20:09, Borja Marcos via freebsd-stable wrote: >>>=20 >>>=20 >>>=20 >>>> On 3 May 2019, at 11:55, Pete French wrote:= >>>>=20 >>>>=20 >>>>=20 >>>>> On 03/05/2019 08:09, Borja Marcos via freebsd-stable wrote: >>>>>=20 >>>>> The right way to use disks is to give ZFS access to the plain CAM devi= ces, not thorugh some so-called JBOD on a RAID >>>>> controller which, at least for a long time, has been a *logical* =E2=80= =9CRAID0=E2=80=9D volume on a single disk. That additional layer can >>>>> completely break the semantics of transaction writes and cache flushes= . >>>>> With some older cards it can be tricky to achieve, from patching sourc= e drivers to enabling a sysctl tunable or even >>>>> flashing the card to turn it into a plain HBA with no RAID features (o= r minimal ones). >>>>=20 >>>> Oddly enough I got bitten by something like this yesteray. I have a mac= hine containing an HP P400 RAID controller, which is nice enough, but I run Z= FS so I have made the drives all into RAID-0 as being as close as I can get t= o accessing the raw SAS drives. >>=20 >> I got bitten by that on this hardware originally... switching to raid-0 a= nd separate drives then switching to write-through (not write back and defin= itely not write back with bad bbu) seemed to solve it. >=20 > I have an old Dell R610 with a PERC 6/i and Megaraid SAS driver Ver 4.23. > When I use mfiutil to set caching to write through it still goes through > the cache. Which means that if a drive fails and the machine reboots the > firmware stops the boot because it has data in the cache that it wants > to store on the failed drive. So a normal failure of a drive in a three > way ZFS mirror that shouldn't cause a loss of service actually does. >=20 I don=E2=80=99t think it will do that in write through.. it will everytime i= n write back. > Thumbs down to RAID cards. > --=20 > Kevin P. Neal http://www.pobox.com/~kpn/ >=20 > "Good grief, I've just noticed I've typed in a rant. Sorry chaps!" > Keir Finlow Bates, circa 1998 > _______________________________________________ > freebsd-stable@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"