Date: Thu, 24 Sep 2015 14:15:43 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: John Nielsen <lists@jnielsen.net> Cc: Edward Tomasz =?koi8-r?Q?Napierala?= <trasz@freebsd.org>, freebsd-current Current <freebsd-current@freebsd.org>, aoyama@peach.ne.jp, Yonas Yanfa <yonas@fizk.net> Subject: Re: Add isboot iSCSI boot driver to FreeBSD Message-ID: <20150924111543.GZ3158@zxy.spb.ru> In-Reply-To: <404EF3F8-B8CB-4703-90AF-11FBA1CD2A7F@jnielsen.net> References: <56025EEE.50404@fizk.net> <5B296016-F14D-48A9-8DC6-0D8EA28AE891@jnielsen.net> <20150923212520.GA7390@brick> <404EF3F8-B8CB-4703-90AF-11FBA1CD2A7F@jnielsen.net>
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On Wed, Sep 23, 2015 at 05:21:00PM -0600, John Nielsen wrote: > On Sep 23, 2015, at 3:25 PM, Edward Tomasz Napierala <trasz@freebsd.org> wrote: > > > On 0923T0916, John Nielsen wrote: > >> On Sep 23, 2015, at 2:12 AM, Yonas Yanfa <yonas@fizk.net> wrote: > >> > >>> isboot is a iSCSI boot driver written by Daisuke Aoyama that allows you to boot your root partition using iSCSI. > >> [,,,] > >>> This was first announced way back in June, 2010: > >>> > >>> https://lists.freebsd.org/pipermail/freebsd-scsi/2010-June/004425.html > >>> > >>> I've tested the current version (v0.2.10) and it works with FreeBSD 10.2 booting a ZFS on root installation: > >>> > >>> http://www.peach.ne.jp/archives/isboot/isboot-0.2.10.tar.gz > >>> > >>> I've used iSCSI boot with Ubuntu Server for a while and it's been very useful. I'm looking forward to FreeBSD having the same capability built-in. > >> > >> +1. I have used this module in the past and it is extremely useful. Thanks for the pointer, I wasn't aware it had been updated for FreeBSD 10.x so recently. I've also wondered why this is not part of FreeBSD by default. > >> > >> Aoyama-san, do you have any objection to this code being included in FreeBSD? If not, can you formally assign it a BSD or other friendly license? Thank you again for the work! > >> > >> Trasz (or anyone), is there other work to support iSCSI booting and/or IBFT on FreeBSD? Anything else isboot might conflict with? Any problems with integrating the code or with the code itself? > > > > The basic problem with isboot is that it only works with the old iSCSI > > initiator, which is now marked obsolete. AFAIK there is no ready solution > > that works with the new one - however, it should be possible to use upcoming > > reroot support to achieve this: boot with a temporary rootfs, mounted from > > a ramdisk preloaded by loader(8), setup an iSCSI session, and then replace > > the temporary rootfs with the real one, mounted over iSCSI. > > Ah, thank you for clarifying. I forgot that 10.x still supports the old initiator. > > The reroot approach sounds interesting but less straightforward. The beauty of isboot is that the kernel-loaded from a normal root disk that happens to be iSCSI-connected-knows how to re-establish its network and iSCSI connections just from the information in the iSCSI Boot Firmware Table, i.e. native iSCSI booting. I'd love to see the same approach continued with the new initiator. I suspect that a new implementation could re-use all of the IBFT code and most of the networking code, but I don't know how hard the remaining pieces would be. I may have a chance to look in to it but a kernel programmer I am not, sadly. > > I think a "native" iSCSI reroot approach could be feasible at some > point; for me that would mean that the loader could load the kernel > and a standard-ish (or easily auto-generated) mfsroot from the iSCSI > volume seamlessly, then something in the mfsroot parses the IBFT and > sets up the network and iSCSI connections before switching root. mfsroot auto-generated by loader? cool for stay in sync mfsroot with main tree.
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