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Difference between revisions of "Solid State Drives (SSD)"
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'''I/O Scheduler''' | '''I/O Scheduler''' | ||
'''Reduce swappiness to swap partition on an SSD''' | |||
In instances where a low memory system may need to place a swap partition on an SSD; a recommended tweak is to reduce the swappiness of the system to some very low value (for example 1 or 10), thus avoiding unneccesary writes to swap. | In instances where a low memory system may need to place a swap partition on an SSD; a recommended tweak is to reduce the swappiness of the system to some very low value (for example 1 or 10), thus avoiding unneccesary writes to swap. | ||
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vm.swappiness=1 | vm.swappiness=1 | ||
vm.vfs_cache_pressure=50 | vm.vfs_cache_pressure=50 | ||
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'''Use tmpfs for /tmp, /var/tmp, etc.''' | '''Use tmpfs for /tmp, /var/tmp, etc.''' | ||
Revision as of 14:18, May 6, 2015
Solid State Drives (SSDs)...
Preparation
This section is in need of updates.
Partitioning
- MBR/GPT partitioning
- LVM
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)
- mdadm RAID
mdadm -c 512 Aligns chunksize to 512KB erase block size times 1 data disk (for raid1)
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)
- Encrypted with dmcrypt/LUKS
cryptsetup luksFormat --align-payload 2048 (default)
cryptsetup luksOpen --allow-discards
File systems
- EXT4
- ZFS
- Others
Installation
This section is in need of updates.
(Optional) Clearing SSD Memory Cells
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. [1]
Partition creation and alignment
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.
Create File Systems
/etc/fstab, mount
SSD Optimization
This section is in need of updates.
Enable TRIM
Mount Options
noatime
I/O Scheduler
Reduce swappiness to swap partition on an SSD
In instances where a low memory system may need to place a swap partition on an SSD; a recommended tweak is to reduce the swappiness of the system to some very low value (for example 1 or 10), thus avoiding unneccesary writes to swap.
root # nano /etc/sysctl.conf
vm.swappiness=1 vm.vfs_cache_pressure=50
Use tmpfs for /tmp, /var/tmp, etc.