storage devices

storage devices

some quick notes about cli ops for storage devices

storage devices

useful commands

can give you some useful info about your physical drives

apt-get install lshw
    lshw -class disk


blkid can give you a nice formatted list of partitions. remember that only partitions have UUIDs, not devices.

blkid -o list

you need the gdisk package for this. It pretty much does magical partition table stuff like sgdisk -R /dev/sdY /dev/sdX will copy the partition table from sdX to sdY. It does it instantly too, which is pretty cool.

this one is pretty rad, it gives you the devices physical information, like a serial number, from a /dev/sdx type address. This is obscenely useful if you're trying to figure out which drive is dead. Pro tip: write the serial number of a drive somewhere you can see it easily. In my own case right now I have to physically remove each drive to find each one.

occasionally you might be looking at the output from blkid trying to figure out where the hell your OS is, you can use cat /etc/fstab to do that.

fdisk -l will tell you what device has what partitions.

blocks & inodes

This is just my working theory.. so I could be way off base here. A partition with no filesystem is just a huge string of bits. Obviously you want to divide this bits into segments, which are called blocks. And of course you're going to want to label those segments, so you specify a certain portion of each block to be the label, (inode).

That's why, as discussed here mkfs allows you to specify both the inode size, and the bytes-per-inode.

ext3 has 128 bytes-to-inode and ext4 has 256. grub has problems working with 256.. seems weird to me that you can install debian to ext4, but then can't install grub?