Date: Wed, 30 Mar 2022 20:19:46 -0700 From: David Christensen <dpchrist@holgerdanske.com> To: questions@freebsd.org Subject: Re: difficulties replacing a ZFS installer zroot pool with a new zroot pool on a new disk Message-ID: <4028e4ee-dea5-cec0-ea4e-da14344275c1@holgerdanske.com> In-Reply-To: <c69c61b5-726c-4058-564f-6c541f50bba2@pinyon.org> References: <899c1dd2-30f5-5e3d-f4bb-91d29011c8be@pinyon.org> <d72c2328-86b2-0c55-7069-ece31cc07a3e@holgerdanske.com> <c69c61b5-726c-4058-564f-6c541f50bba2@pinyon.org>
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On 3/30/22 15:22, Russell L. Carter wrote: > Greetings, > I am going to top post because all of the previous discussion > is moot given what I have found out to get the problem solved, > where the problem is to simply replace a ZFS system pool's drive > with a new drive. > > To begin from the start: > > I installed the new NVMe SSD drive and I was able to boot the USB > install image and install a new FreeBSD system on it. On reboot I > first tried keeping the old SATA drive as it was. However the > motherboard BIOS (CSM enabled, legacy, ASUS Prime X570-PRO) refused > all of my efforts to set the boot drive to the new SSD. I finally > resorted to disconnecting the data cable of the old SATA drive, and > the new SSD booted fine. I then powered down the motherboard, > reattached the old SATA data cable, and booted. The motherboard again > refused to boot the new NVMe SSD. After about an hour of fighting the > BIOS, I gave up, set the SATA drive as "hot pluggable" in the BIOS, > and rebooted with the SATA data cable disconnected. Once the NVMe SSD > was booted, I reattached the SATA data cable and it showed up in the > 'zpool import' list. 'zpool import zroot' was not a happy solution as > it collided with the new SSD zroot pool. > > I eventually worked out that I should rename the old pool zroot.old on > import. That was also not a happy solution as it continued to > automatically mount itself on top of the new SSD zroot pool. I then > worked out that I need to specify an altroot: > > zpool import -o altroot=/mnt/zroot.old zroot.old > > This at first glance appeared to work. But it did NOT. I was left with > the complaint I made in my original email to the freebsd-questions list: > > Where are my subsidiary datasets, and especially their data? > zfs mount -a, for instance, did nothing, very quietly. > > I tried zfs-mount(8)ing several of the subsidiary datasets (eg > zroot.old/usr/src), and that worked! But still I was missing some > important stuff, like /root and /usr/local. To get /root, I made > a wild guess, and tried: > > zfs mount zroot.old/ROOT/default > > And that brought all my subsidiary datasets (and the data) back. > > I would submit that looking back on 30+ years of successfully > performing this exercise, that having the old SSD zroot.orig > automatically import and mount everything, but not automatically > import and mount everything when set given an altroot, is confusing. > I would add that manually performing > > zfs mount zroot.old/ROOT/default > > (but not, say zfs unmount zroot.old/usr; zfs mount zroot.old/src) > > mount everything I was missing, is also confusing and unintuitive. > > I have two more ZFS system pools to upgrade to SSDs. I am going to > try the following procedure: > > 1) unplug the old SATA drive and install FreeBSD to the new SSD. > > 2) shutdown, reattach old drive, reboot > If the new drive boots (instead of the old drive), I boot > to single user. I then try > > zpool import -o altroot /mnt/zrool.old zroot zroot.old > > 3) If that works, I try: > > zfs mount zpool.old/ROOT/default > > 4) If it doesn't work, I'll probably have to zpool export the pool and > iterate. I forget exactly how I got the old pool renamed in the > above. > > Anyway, onwards. > > Russell I am glad you were able to navigate those obstacles and get FreeBSD running on NVMe. The performance improvement must be dramatic. :-) I suggest that you try cloning the two more ZFS system pools from their old devices to their new devices (same or larger size) using a live OS instance that does not automatically react to ZFS. (I believe the FreeBSD installer has this property, but am not certain.) When I was cloning ZFS FreeBSD instances between SSD's and USB flash drives using MBR partitioning, often the target device would not boot. Solutions included connecting the target device to a different port and using the FreeBSD installer live system/ shell to delete /boot/zfs/zpool.cache on the target device. David
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