From mboxrd@z Thu Jan 1 00:00:00 1970 From: Muneendra Kumar M Subject: Re: deterministic io throughput in multipath Date: Wed, 4 Jan 2017 13:26:01 +0000 Message-ID: <5622482d0db74f25b7780e32678efcac@BRMWP-EXMB12.corp.brocade.com> References: <1649d4b8538d4b4cb1efacdfe8cf31eb@BRMWP-EXMB12.corp.brocade.com> <20161221160940.GG19659@octiron.msp.redhat.com> <8cd4cc5f20b540a1b8312ad485711152@BRMWP-EXMB12.corp.brocade.com> <20170103171159.GA2732@octiron.msp.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20170103171159.GA2732@octiron.msp.redhat.com> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Benjamin Marzinski Cc: "dm-devel@redhat.com" List-Id: dm-devel.ids Hi Ben, Thanks for the information. Regards, Muneendra. -----Original Message----- From: Benjamin Marzinski [mailto:bmarzins@redhat.com] = Sent: Tuesday, January 03, 2017 10:42 PM To: Muneendra Kumar M Cc: dm-devel@redhat.com Subject: Re: [dm-devel] deterministic io throughput in multipath On Mon, Dec 26, 2016 at 09:42:48AM +0000, Muneendra Kumar M wrote: > Hi Ben, > = > If there are two paths on a dm-1 say sda and sdb as below. > = > # multipath -ll > mpathd (3600110d001ee7f0102050001cc0b6751) dm-1 SANBlaze,VLUN MyLun > size=3D8.0M features=3D'0' hwhandler=3D'0' wp=3Drw > `-+- policy=3D'round-robin 0' prio=3D50 status=3Dactive > |- 8:0:1:0 sda 8:48 active ready running > `- 9:0:1:0 sdb 8:64 active ready running = > = > And on sda if iam seeing lot of errors due to which the sda path is fluct= uating from failed state to active state and vicevera. > = > My requirement is something like this if sda is failed for more then 5 = > times in a hour duration ,then I want to keep the sda in failed state = > for few hours (3hrs) > = > And the data should travel only thorugh sdb path. > Will this be possible with the below parameters. No. delay_watch_checks sets how may path checks you watch a path that has r= ecently come back from the failed state. If the path fails again within thi= s time, multipath device delays it. This means that the delay is always tr= igger by two failures within the time limit. It's possible to adapt this t= o count numbers of failures, and act after a certain number within a certai= n timeframe, but it would take a bit more work. delay_wait_checks doesn't guarantee that it will delay for any set length o= f time. Instead, it sets the number of consecutive successful path checks = that must occur before the path is usable again. You could set this for 3 h= ours of path checks, but if a check failed during this time, you would rest= art the 3 hours over again. -Ben > Can you just let me know what values I should add for delay_watch_checks = and delay_wait_checks. > = > Regards, > Muneendra. > = > = > = > -----Original Message----- > From: Muneendra Kumar M > Sent: Thursday, December 22, 2016 11:10 AM > To: 'Benjamin Marzinski' > Cc: dm-devel@redhat.com > Subject: RE: [dm-devel] deterministic io throughput in multipath > = > Hi Ben, > = > Thanks for the reply. > I will look into this parameters will do the internal testing and let you= know the results. > = > Regards, > Muneendra. > = > -----Original Message----- > From: Benjamin Marzinski [mailto:bmarzins@redhat.com] > Sent: Wednesday, December 21, 2016 9:40 PM > To: Muneendra Kumar M > Cc: dm-devel@redhat.com > Subject: Re: [dm-devel] deterministic io throughput in multipath > = > Have you looked into the delay_watch_checks and delay_wait_checks configu= ration parameters? The idea behind them is to minimize the use of paths th= at are intermittently failing. > = > -Ben > = > On Mon, Dec 19, 2016 at 11:50:36AM +0000, Muneendra Kumar M wrote: > > Customers using Linux host (mostly RHEL host) using a SAN network for > > block storage, complain the Linux multipath stack is not resilient to > > handle non-deterministic storage network behaviors. This has caused = many > > customer move away to non-linux based servers. The intent of the bel= ow > > patch and the prevailing issues are given below. With the below desi= gn we > > are seeing the Linux multipath stack becoming resilient to such netw= ork > > issues. We hope by getting this patch accepted will help in more Lin= ux > > server adoption that use SAN network. > > = > > I have already sent the design details to the community in a differe= nt > > mail chain and the details are available in the below link. > > = > > [1]https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.redhat= .com_archives_dm-2Ddevel_2016-2DDecember_msg00122.html&d=3DDgIDAw&c=3DIL_Xq= QWOjubgfqINi2jTzg&r=3DE3ftc47B6BGtZ4fVaYvkuv19wKvC_Mc6nhXaA1sBIP0&m=3DvfwpV= p6e1KXtRA0ctwHYJ7cDmPsLi2C1L9pox7uexsY&s=3Dq5OI-lfefNC2CHKmyUkokgiyiPo_Uj7M= Ru52hG3MKzM&e=3D . > > = > > Can you please go through the design and send the comments to us. > > = > > =A0 > > = > > Regards, > > = > > Muneendra. > > = > > =A0 > > = > > =A0 > > = > > References > > = > > Visible links > > 1. = > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.redhat.com_ > > ar = > > chives_dm-2Ddevel_2016-2DDecember_msg00122.html&d=3DDgIDAw&c=3DIL_XqQWOj > > ub = > > gfqINi2jTzg&r=3DE3ftc47B6BGtZ4fVaYvkuv19wKvC_Mc6nhXaA1sBIP0&m=3DvfwpVp6e > > 1K = > > XtRA0ctwHYJ7cDmPsLi2C1L9pox7uexsY&s=3Dq5OI-lfefNC2CHKmyUkokgiyiPo_Uj7M > > Ru > > 52hG3MKzM&e=3D > = > > -- > > dm-devel mailing list > > dm-devel@redhat.com > > https://urldefense.proofpoint.com/v2/url?u=3Dhttps-3A__www.redhat.com_ > > ma = > > ilman_listinfo_dm-2Ddevel&d=3DDgIDAw&c=3DIL_XqQWOjubgfqINi2jTzg&r=3DE3f= tc4 > > 7B6BGtZ4fVaYvkuv19wKvC_Mc6nhXaA1sBIP0&m=3DvfwpVp6e1KXtRA0ctwHYJ7cDmPsL > > i2C1L9pox7uexsY&s=3DUyE46dXOrNTbPz_TVGtpoHl3J3h_n0uYhI4TI-PgyWg&e=3D