Date: Fri, 27 Oct 2017 09:55:23 -0600 From: Warner Losh <imp@bsdimp.com> To: Ian Lepore <ian@freebsd.org> Cc: Alan Somers <asomers@freebsd.org>, Warner Losh <imp@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "svn-src-head@freebsd.org" <svn-src-head@freebsd.org> Subject: Re: svn commit: r325026 - head/sys/cam/ata Message-ID: <CANCZdfp3r1y1dfMDcQgmkLPgknBf%2BZgEY7y2ot4SypOt=656ow@mail.gmail.com> In-Reply-To: <1509119530.56824.75.camel@freebsd.org> References: <201710262253.v9QMrovZ009495@repo.freebsd.org> <CAOtMX2gFAj-yQzG6pwNmjAWYaw8_o3RHRfiAVURfNd7ib-BFZg@mail.gmail.com> <CANCZdfpg0MK_Smui%2B=7SWwBdJbCURJiyoXii4DXpnTP0K-wO9w@mail.gmail.com> <CANCZdfp5=Q1%2BYcPhC1fDHBZqCoVAUf8%2BtZQGboCOsUaHjmpz1A@mail.gmail.com> <1509119530.56824.75.camel@freebsd.org>
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On Fri, Oct 27, 2017 at 9:52 AM, Ian Lepore <ian@freebsd.org> wrote: > On Thu, 2017-10-26 at 20:27 -0600, Warner Losh wrote: > > On Thu, Oct 26, 2017 at 5:35 PM, Warner Losh <imp@bsdimp.com> wrote: > > > > > > > > > > > > > > On Thu, Oct 26, 2017 at 5:04 PM, Alan Somers <asomers@freebsd.org> > wrote: > > > > > > > > > > > On Thu, Oct 26, 2017 at 4:53 PM, Warner Losh <imp@freebsd.org> > wrote: > > > > > > > > > > Author: imp > > > > > Date: Thu Oct 26 22:53:49 2017 > > > > > New Revision: 325026 > > > > > URL: https://svnweb.freebsd.org/changeset/base/325026 > > > > > > > > > > Log: > > > > > Always send STANDBY IMMEDIATE when shutting down > > > > > > > > > > To save SMART data and for a drive to understand that it's been > nicely > > > > > shutdown, we need to send a STANDBY IMMEDIATE. Modify > adaspindown to > > > > > use a local CCB on the stack. When we're panicing, used > > > > > xpt_polled_action rather than cam_periph_runccb so that we can > SEND > > > > > IMMEDIATE after we've shutdown the scheduler. > > > > > > > > > > Sponsored by: Netflix > > > > > Reviewed by: scottl@, gallatin@ > > > > > Differential Revision: https://reviews.freebsd.org/D12799 > > > > > > > > > > Modified: > > > > > head/sys/cam/ata/ata_da.c > > > > Will this put the drive into a standby state just prior to a warm > > > > reboot? That could cause lengthy delays on the new boot while the > > > > drives spin up. That behavior caused a problem when the mpr driver > > > > did it to a JBOD full of 96 SATA drives. On the new boot, each drive > > > > spun up one at a time while they were being probed. Eventually the > > > > system paniced because run_interrupt_driven_hooks timed out. With > > > > mpr, I was able to fix the problem by setting hw.mpr.enable_ssu=0. > > > > > > > That's a good question. The standard is silent about what, exactly, the > > > Standby state means. We already allow this to be disabled, and this > commit > > > doesn't change that. It looks like IDLE IMMEDIATE also forces SMART > media > > > non volatile to be flushed out. > > > > > > What do you suggest? > > > > > I see two paths forward. We need to flush the NV SMART data at reboot > time. > > SSDs that we use, at least, consider it an unclean shutdown if you don't > > Idle the drive on reboot because part of that process does a > > COMINIT/COMRESET and if the drive is in the Active state, it ticks up the > > counter (and with at least one vendor can lose NV SMART data). > > > > So, path forward #1 is that we do STANDBY IMMEDIATE for SSDs in the > > RB_REBOOT case or all drives in the other cases. For HDD and RB_REBOOT we > > do only a IDLE IMMEDIATE which shouldn't spin the drives down. > > IDLE will actually spin drives up -- my 'spinup' script is just a > series of 'camcontrol idle ada#' commands for all the backup drives > that are usually in standby. > > If IDLE does the necessary flushing, then why not STANDBY in the power- > down/cycle case and IDLE in all other cases, regardless of drive type? > The only point in using STANDBY at all would be to avoid spinning up > drives just before powering them down. https://reviews.freebsd.org/D12811 does exactly this. Alan suggested something similar. Maybe you could "give it a spin" on that crazy system of yours we chatted about on IRC and see if that helps... Warner > > -- Ian > > > This seems > > to bake in what we know about storage devices and is easiest for the > user. > > If we get it right, it's easier for the user. If we get it wrong, the > user > > can disable all spin downs. > > > > Path forward #2 is to just make what we send a sysctl. This is > unsatisfying > > and error-prone, but gives the most flexibility. I don't like this. > > > > I'd be curious if there's another viable path forward I'm not seeing that > > you might know. > > > > FWIW, we don't connect HDDs to our AHCI ports (they are all on > MPT/MPS/MPR > > HBAs), so we've not seen any issues in the 6 or so months we've had this > in > > the tree. > > > > Warner >
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