Solid State Drives (SSD)

Revision as of 13:21, December 1, 2014 by Tassietux (Talk | contribs)


This page aims to highlight SSD relevant options for commands commonly used during system setup/install.

Installation

Important

This section is in need of updates.

Partitioning

Important

This section is in need of updates.

The default alignment of 1MiB provides for proper SSD performance. For gdisk, ensure each partition starts at integer multiple of 2048 (sectors). If you change gdisk's default boundary then the default for other programs may change as a result.

Cryptsetup/LUKS

Important

This section is in need of updates.

cryptsetup luksFormat --align-payload 2048 (default)
cryptsetup luksOpen --allow-discards

mdadm RAID

Important

This section is in need of updates.

mdadm -c 512 Aligns chunksize to 512KB erase block size times 1 data disk (for raid1)

LVM

Important

This section is in need of updates.

pvcreate --data-alignment 512 (equal to value given as chunksize) ?default? --data-alignment-offset (should not be needed for correctly aligned partitions)
vgcreate -s 4M (default)

Create File System

Important

This section is in need of updates.

mkfs.ext4 -b 4096 -E stride=128,stripe_width=128 (erase block size / 4096) (for raid1)
mkfs.xfs -b 4096 -d sunit=1024,swidth=1024 OR -d su=512K,sw=512K (for raid1)

Clearing SSD Memory Cells

Important

This section is in need of updates.

WARNING
Avoid using dd command to overwrite data on SSD. The SSD controller has its own algorithms for allocating writes based on its internal topology. Trying to overwrite data the usual way (e.g. dd if=/dev/zero of=/dev/sda ) is not only futile but will reduce the remaining number of writes to the flash cells. To inform the controller that all data can be purged use hdparm --security-erase. <ref>https://wiki.archlinux.org/index.php/SSD_Memory_Cell_Clearing</ref>