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 * by adding the "elevator=noop" kernel option to /etc/default/grub (and running update-grub).

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This describe SDD optimization with system having encrypted root and swap.

/!\ An important aspect in optimizing SSD performance is the file system and partition alignment (1 MiB borders aligned to the 4096 byte blocks of the hardware). This wiki page does not cover these issues.

Reducing writes to solid state disks (SSDs) or laptop hard disk drives (HDDs)

  • Disable or reduce disk writes during disk read access.
    • Set "noatime" or "relatime" mount option in /etc/fstab.
  • set RAMTMP, RAMRUN and RAMLOCK to "yes" in /etc/default/tmpfs (since wheezy)
    • /!\ RAMTMP will keep /tmp in RAM only, causing its content to be discarded on shutdown! Using increasing the commit interval or using sync scripts (see below) shall reduce disk writes significantly without regularly discarding data.

  • Make system flush data to the disk every 10 minutes for laptop PCs.

    /!\ Attention: Changing the flushing interval from default 5 seconds to 10 minutes (or until proper shutdown) makes your data more vulnerable in case of lock-ups or power failures.

Optimizations for solid state disks (SSDs)

Performance and disk wear of the solid state drive (SSD) can be optimized as follows.

  • Use a recent Linux kernel. (>3.2)

  • by adding the "elevator=noop" kernel option to /etc/default/grub (and running update-grub).
  • Maybe enable the "discard" filesystem options for automatic/online TRIM. However this is not strictly necessary if your SSD has enough overprovisioning (spare space) or you leave (unpartitioned) free space on the SSD (http://www.spinics.net/lists/raid/msg40866.html). Enabling online-trim in fstab may just slow down some SSDs signficantly (https://patrick-nagel.net/blog/archives/337).

    • Set "discard" mount option in /etc/fstab for the ext4 filesystem, swap partition, Btrfs, etc. See mount(8).
    • Set "discard" option in /etc/lvm/lvm.conf for LVM. See lvm.conf(5).
    • Set "discard" option in /etc/crypttab for dm-crypt.

Note that using discard with on-disk-cryptogrpahy (like dm-crypt) also has drawbacks with respect to security/cryptography! See crypttab(5).

dm-crypt's /etc/crypttab:

#<target name>    <source device>            <key file>  <options>
var  UUID=01234567-89ab-cdef-0123-456789abcdef  none  luks,discard
  • You'll also need to update your initramfs: update-initramfs -u -k all

  • Optionally, set up an offline-trim cronjob that runs time fstrim -v  (or mdtrim) on the ssd mountpoints periodically. Until software raid (md device layer) has trim support, you could use something like mdtrim (https://github.com/Cyberax/mdtrim/).

  • With btrfs, set "ssd" mount option in /etc/fstab to enable the SSD optimized disk space allocation scheme.

More: http://siduction.org/index.php?module=news&func=display&sid=78 http://forums.debian.net/viewtopic.php?f=16&t=76921 https://wiki.archlinux.org/index.php/SSD http://wiki.ubuntuusers.de/SSD


# /etc/fstab: static file system information.
# Use 'vol_id --uuid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
### SSD: discard,noatime
### match battery operation default for commit JOURNAL_COMMIT_TIME_AC in Add files in /etc/pm/config.d/*
/dev/mapper/goofy-root /               ext4    discard,noatime,commit=600,errors=remount-ro 0       1
# /boot was on /dev/sda1 during installation
UUID=709cbe4a-80c1-46cb-8bb1-dbce3059d1f7 /boot           ext4    discard,noatime,commit=600,defaults        0       2
### SSD: discard
/dev/mapper/goofy-swap none            swap    sw,discard              0       0
/dev/mapper/goofy-chroot /srv/chroot         btrfs    ssd,discard,noatime 0       2
/dev/scd0       /media/cdrom0   udf,iso9660 user,noauto     0       0


# This section allows you to configure which block devices should
# be used by the LVM system.
devices {
    # Issue discards to a logical volumes's underlying physical volume(s) when
    # the logical volume is no longer using the physical volumes' space (e.g.
    # lvremove, lvreduce, etc).  Discards inform the storage that a region is
    # no longer in use.  Storage that supports discards advertise the protocol
    # specific way discards should be issued by the kernel (TRIM, UNMAP, or
    # WRITE SAME with UNMAP bit set).  Not all storage will support or benefit
    # from discards but SSDs and thinly provisioned LUNs generally do.  If set
    # to 1, discards will only be issued if both the storage and kernel provide
    # support.
    # 1 enables; 0 disables.
    #issue_discards = 0
    issue_discards = 1

Smaller system with SSD