Date: Fri, 17 Feb 2023 20:03:49 +0300 From: Andrey Fesenko <f0andrey@gmail.com> To: Alan Somers <asomers@freebsd.org> Cc: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: RFC: GEOM and hard disk LEDs Message-ID: <CA%2BK5SrPTLVrJwRP5PuQkiCJ0WVMY3dycNWLU5C_ZEKuF2XQKrw@mail.gmail.com> In-Reply-To: <CAOtMX2hH5gEMj4tO2rq-x2DeRuB-o6RD83i-V1LB8F2T77GRCw@mail.gmail.com> References: <CAOtMX2h5=xCH1CN3ravsOLfmeMq=1-BOw1aSFGKVP-js6g38GA@mail.gmail.com> <CAOtMX2hH5gEMj4tO2rq-x2DeRuB-o6RD83i-V1LB8F2T77GRCw@mail.gmail.com>
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On Wed, Feb 8, 2023 at 2:31 AM Alan Somers <asomers@freebsd.org> wrote: > > Most modern SES backplanes have two LEDs per hard disk. There's a > "fault" LED and a "locate" LED. You can control either one with > sesutil(8) or, with a little more work, sg_ses from > sysutils/sg3_utils. They're very handy for tasks like replacing a > failed disk, especially in large enclosures. However, there isn't any > way to automatically control them. It would be very convenient if, > for example, zfsd(8) could do it. Basically, it would just set the > fault LED for any disk that has been kicked out of a ZFS pool, and > clear it for any disk that is healthy or is being resilvered. But > zfsd does not do that. Instead, users' only options are to write a > custom daemon or to use sesutil by hand. Instead of forcing all of us > to write our own custom daemons, why not train zfsd to do it? > > My proposal is to add boolean GEOM attributes for "fault" and > "locate". A userspace program would be able to look up their values > for any geom with DIOCGATTR. Setting them would require a new ioctl > (DIOCSATTR?). The disk class would issue a ENCIOC_SETELMSTAT to > actually change the LEDs whenever this attribute changes. GEOM > transforms such as geli would simply pass the attribute through to > lower layers. Many-to-one transforms like gmultipath would pass the > attribute through to all lower layers. zfsd could then set all vdevs' > fault attributes when it starts up, and adjust individual disk's as > appropriate on an event-driven basis. > > Questions: > > * Are there any obvious flaws in this plan, any reasons why GEOM > attributes can't be used this way? > > * For one-to-many transforms like gpart the correct behavior is less > clear: what if a disk has two partitions in two different pools, and > one of them is healthy but the other isn't? > > * Besides ZFS, are there any other systems that could take advantage? > > * SATA enclosures uses SGPIO instead of SES. SGPIO is too limited, > IMHO, to be of almost any use at all. I suggest not even trying to > make it work with this scheme. > > <Originally posted to freebsd-geom; reposting here for a larger audience> > old dreams https://people.freebsd.org/~mav/Enclosure_Management_en.pdf TODO: – add support for SGPIO/I2C interfaces in more drivers, – associate devices with enclosure slots for non-SAS enclosures; – implement in-kernel interface for the «enc» CAM driver; – refactor GEOM::setstate API to handle full set of SES Array Device Slot flags; – explore possibility to make ZFS report disks statuses to GEOM using that API.
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