Storage¶
File Systems¶
Btrfs¶
Btrfs is intended to address the lack of pooling, snapshots, checksums, and integral multi-device spanning in Linux file systems.
The file system’s on-disk format has been declared stable in the Linux kernel.
Features:
Copy-on-write
Btrfs Snapshots
Built-in RAID support
Online resizing and defragmentation
Transparent compression
References:
ZFS¶
Unlike most files systems, ZFS combines the features of a file system and a volume manager. This means that unlike other file systems, ZFS can create a file system that spans across a series of drives or a pool. Not only that but you can add storage to a pool by adding another drive. ZFS will handle partitioning and formatting.
Features:
Pooled storage
Copy-on-write
Snapshots
Data integrity verification and automatic repair
RAID-Z
Maximum 16 Exabyte file size
Maximum 256 Quadrillion Zettabytes storage
References:
RAID¶
Level |
Description |
|---|---|
0 |
Stripping |
1 |
Mirrored |
5 |
Striping with parity |
6 |
Striping with double parity |
10 |
Combining RAID 1 & RAID 0 |
References:
RAID-Z¶
The ZFS filesystem provides RAID-Z, a data/parity distribution scheme similar to RAID 5, but using dynamic stripe width: every block is its own RAID stripe, regardless of blocksize, resulting in every RAID-Z write being a full-stripe write.
Notes:
RAID-Z is a variant of RAID-5.
When drives are added to the RAID-Z pools, they have to be added in multiples of two.
SHR¶
aka Synology Hybrid RAID
References:
Secure Delete¶
Delete and overwrite hard drives to garuntee that the contents cannot be recovered.
HDD¶
The shred command overwrites specified files repeatedly to make recovery extremely difficult to recover.
$ time shred -vfz /dev/<drive>
Notes:
It takes about 31 hours/tb when connected via USB3
Do not use on SSD disks
References:
SDD¶
blkdiscard will discard all blocks on the device. Options may be used to modify this behavior based on range or size.
The “secure erase” is the fastest way to make all content on SSD inaccessible and it’s secure by specification not by accident.
Notes:
Secure erase and blkdiscard require that the device be connected via a SATA controller and is unlikely to work via a USB to PATA/SATA Bridge
References: