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I've had yet another drive fail in one of my old Linux servers, this was an old 2.5" mechanical just used for booting... so I'm able to go in; just about; and copy all the data off of the machine.
However, the USB-flash drive I chose as my life-boat was being a bit of a pain, here's the commands I did:
ls /dev/sd*
(and note down the replies)
(insert the USB-Stick)
ls /dev/sd*
(note the label of the new drive, for me this is /dev/sdc)
sudo fdisk /dev/sdc
(delete the existing exFat partition)
(new partition max size - of Linux type)
(write & exit)
sudo mkfs.ext4 /dev/sdc1
mkdir ~/external
sudo mount /dev/sdc1 ~/external
sudo chown <myUser> ~/external/
rsync -a -v /myData/ ~/external
I could "sudo" rsync and save the need to chown, but here you go.
Since this... interesting post of mine... has only about 10 views, and my tech items usually get a few hundred, I figure somewhere along the lines it got trampled by my silly New Years post....
This post comes from an idea I had to allow me to easily carry a ZFS mirror away from a site and back again, we didn't need much space - only 5gb - but it had to be mirrored in triplicate, one copy to stay locally, one going into a fire safe on site and the third to be carried by the IT manager off-site each evening.
The trouble? A near zero budget, so for a little over £45 we have a 14GB ZFS mirrored pool, across three 16 GB USB Flash drives and one three port USB 3.0 hub.
It was perfect for the task at hand, extremely portable, and cheap, I thought the same approach may help anyone trying to get to learn a little more about ZFS, a student or even someone using a laptop as a small office server - as the laptop literally has its own battery back-up system built in!
It's not the fastest solution, its in fact extremely slow, but as an entry step it's perfect.
See the full video below, throughout the commands I list were in use...
Commands:
Listing Disks by ID...
ls /dev/disk/by-id
Listing Disks to a file for use in a file script as you see me using...
ls /dev/disk/by-id -1 > disks.txt
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To install ZFS on Debian/Ubuntu linux:
sudo apt-get install zfsutils-linux
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To remove & purge ZFS from your system:
sudo apt-get purge zfsutils-linux
(and you will be left with "/etc/zfs/pool.cache" to remove or back up yourself).
The name we had here was "tank", if you already have data on these disks you will need to add "-f" to force this change through.
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Command to make a file executable - like our sh script:
sudo chmod +x <filename>
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Zpool Commands:
sudo zpool status
sudo zpool import <name>
sudo zpool scrub <name>
sudo zpool clear <name>
You will want to "import" if you completely remove ZFS or move one of your sticks to a new machine etc, simply insert the disk and import the pool by name.
Scrub will be used whenever you return a disk to the pool, remember the point here is to allow you to replicate the data across the three sticks and be able to remove one or two to safe keeping, be that an overnight fire safe, or taking a physical copy with oneself.
Clear is used to remove any errors such as the Pool becoming locked out for writing - which it may if a drive, or all drives are removed - you simply clear the current problem with any pool.
Summary: Remember this is NOT the optimum way to run ZFS, this is actually extremely slow, you are replicating each write over your USB, you can only cache so much in the RAM, but it is not a performance piece, this is about ensuring one replicates data for safe keeping, a small office or your dorm room server setup could be completely provided by a laptop in this manner, it has it's own battery backup, it is quite (if you get the right machine) and really this is a very cheap way to play with ZFS before you move onto other bigger hardware options. Plus, I find the best way to learn about technology is to break it, even a little, and so constantly breaking down your pools by pulling USB sticks out of them is an excellent opener to recovering your pools. Play about first, don't put anything critical on there until you're really happy with the results.
