You don’t really install FreeNAS as you do with some other OS. Instead you have a device (often an USB key) that boots FreeNAS which itself manages your data storage. Indeed why wasting some precious SATA port for a boot device when all you need is a little USB key? Especially when thits boot device is less than 2GB in size.<\/p>\n
The problem with USB keys is that they wear out over time. So it inevitably comes a time when it must be replaced. This is what happened to me a few days ago.<\/p>\n
The freenas-boot<\/i> pool switched to a DEGRADED state because checksum error happened too frequently. Fortunately a zpool scrub freenas-boot<\/i> detected no error, and it seems that zfs was still able to correct those. So instead of reflashing a new USB key and restoring my config backup, I could from FreeNAS itself create a new bootable USB key and replace replace the faulty device in the freenas-boot pool.<\/p>\n
Let’s login on FreeNAS and plug in your new USB key. We first find and verify what is the device name for the USB key, in my case it’s da2<\/i>:<\/p>\n You see that MBR table and a FAT32 partition, in my case it can only be the new USB key. We will replace that with GPT partitions. This will contain a boot partition (MBR boot or EFI boot), and a ZFS partition. As root:<\/p>\n Now it’s time to replace the device:<\/p>\n If you got the message device is too small<\/i>, that is because you’ve been trying to replace a device with another one that is smaller than the original (in term of ZFS partition size I suppose). ZFS requires that you replace a device with another with a size greater or equal to the old one. This can be a problem especially if you have a ZFS partition along with others in the partition table like here, or if the vendor announces a certain disk size but only within a certain approximation. You could result in a disk announced to be the exact same size ending up to be very slighty shorter than your original disk. And as a result you won’t be able to use it to replace any disk in your ZFS pool\/vdev. That’s why some recommend to create ZFS filesystems several percents less than the available disk size.<\/p>\n But since we messed up, instead we will create a pool on the other USB key and use ZFS send\/recv to migrate the files.<\/p>\n We also need to save the original setting for bootfs because FreeNAS has its own way of managing the boot pool. We will set this value later on the new pool.<\/p>\n We still have to change that name from freenas-boot2<\/i> to freenas-boot<\/i>. However we cannot do so on the running instance of FreeNAS because it already has a pool named freenas-boot<\/i>. So, we will import it on another ZFS capable machine and fix its name. <\/p>\n (but if anyone knows how to do this live, I’m interested)<\/p>\n Finally you can clear the old snapshot:<\/p>\n You don’t really install FreeNAS as you do with some other OS. Instead you have a device (often an USB key) that boots FreeNAS which itself manages your data storage. Indeed why wasting some precious SATA port for a boot … Continue reading \r\n$ gpart part show da2\r\n=> 1 60088319 da2 MBR (29G)\r\n 1 31 - free - (16K)\r\n 32 60088288 1 fat32lba (29G)\r\n<\/pre>\n
\r\n# Clean that MBR and create GPT partition table\r\ngpart destroy -F da2\r\ngpart create -s GPT da2\r\n\r\n# If you use MBR boot\r\ngpart add -s 64K -t freebsd-boot da2\r\ngpart bootcode -b \/boot\/pmbr -p \/boot\/gptzfsboot -i 1 da2\r\n\r\n# If you use EFI boot\r\ngpart add -s 128M -t efi da2\r\ngpart bootcode -p \/boot\/boot1.efifat -i 1 da2\r\n\r\n# Create the ZFS partition\r\ngpart add -t freebsd-zfs da2\r\n<\/pre>\n
\r\n$ zpool replace -f freenas-boot da1p2 da2p2\r\ncannot replace da1p2 with da2p2: device is too small\r\n# OOPS! :(\r\n<\/pre>\n
\r\n# Create the pool on the new USB key.\r\n# Note that we have to call it freenas-boot2\r\n# because freenas-boot already exists.\r\nzpool create freenas-boot2 da2p2 \r\n\r\n# Create a recursive snapshot of the original pool\r\n# that we will use to restore the backup. \r\nzfs snapshot -r freenas-boot@restore\r\n\r\n# Send the snapshot from the old to the new USB key.\r\nzfs send -R freenas-boot@restore | zfs recv -F freenas-boot2\r\n<\/pre>\n
\r\n$ zpool get bootfs\r\nNAME PROPERTY VALUE SOURCE\r\nfreenas-boot bootfs freenas-boot\/ROOT\/11.3-U4.1 local\r\n<\/pre>\n
\r\n# On some other ZFS capable host (FreeBSD for instance ;) )\r\n# import the pool and change its name back to freenas-boot.\r\n# The -f is required because it comes from another host.\r\nzpool import -f freenas-boot2 freenas-boot\r\n\r\n# Configure default boot filesystem.\r\n# Remember the value of bootfs we found before on the original pool.\r\nzpool set bootfs=freenas-boot\/ROOT\/11.3-U4.1 freenas-boot\r\n\r\n# Export the pool again.\r\nzpool export freenas-boot\r\n<\/pre>\n
\r\nzfs destroy -R freebsd-boot@restore\r\n<\/pre>\n","protected":false},"excerpt":{"rendered":"