SATA: Difference between revisions

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Serial ATA is specified by the [http://www.sata-io.org/ SATA International Organization]; the most current revision as of 2009-12-31 is June 2009's SATA 3.0. Intel specifies the [http://www.intel.com/technology/serialata/ahci.htm Advanced Host Controller Interface]; as of 2009-12-31, the most recent revision is 1.3 ([[:File:AHCIrev1_3.pdf]]). My [[growlight]] tool can provide a great deal of information about attached SATA devices.

==SAS==

An SFF-8087 connector can fan out to support up to 4 SATA devices.

==SSDs==

* Under ext4, the <tt>discard</tt> mount option must be provided to issue the TRIM command.

* TRIM support can be verified using <tt>hdparm -I</tt> (look under "Commands/Features")

** Btrfs doesn't require any option, supposedly. I don't yet use btrfs.

* GPT is recommended over MBR

* The <tt>noop</tt> I/O scheduler is supposedly superior to CFQ for some SSD's

** <tt>echo noop | sudo tee /sys/block/sdX/queue/scheduler</tt>, but I find this highly dubious

* Performance can drop after extensive use

** Use the secure erase functionality to reset the drive: see [http://forums.extremeoverclocking.com/showthread.php?t=333059 this link] at ExtremeOverclockers

** Again, [[growlight]] can help you here.

==Power Management==

~~What is~~ SATA Link Power Management (~~as seen~~ in [[Power Management|~~powertop~~]] ~~hints~~)?

SATA's Aggressive Link Power Management [http://www.lesswatts.org/tips/disks.php ALPM], specified in SATA 1.x (in conjunction with AHCI-compliant controllers), effects [[Power Management|power savings]] at the serial link (this is independent of disk power management). There's both a "Partial" and "Suspend" mode; Suspend takes longer to enter/exit, and saves more power, than Partial.

==hddtemp==

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==SMART==

There's more info on the [[SMART]] page.

There's more general info on the [[SMART]] page. Generally, '-d ata' is a sufficient descriptor of a device for <tt>smartd</tt> to handle it. Determine [[SMART]] capability with <tt>smartctl -i</tt>:

~~===Are my disks failing?===~~

The one-line executive summary is available for supported disks via the <tt>-Hc</tt> option. <tt>grep</tt> for <tt>"^SMART overall"</tt> and verify <tt>PASSED</tt> as opposed to <tt>FAILING</tt>. If you're already <tt>FAILED</tt>, the command will generally fail in and of itself.

~~===Details, for those interested===~~

Generally, '-d ata' is a sufficient descriptor of a device for <tt>smartd</tt> to handle it. Determine [[SMART]] capability with <tt>smartctl -i</tt>:

<pre>[recombinator](0) $ sudo smartctl -i /dev/sdc

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Checksum: correct

[recombinator](0) $ </pre>

==See ~~Also~~==

==See also==

* "[http://www.~~linuxjournal~~.~~com~~/~~article~~/~~6983 Monitoring Hard Disks with SMART]", Linux Journal 2004~~-01-01

* LessWatts.org [http://www.lesswatts.org/projects/devices-power-management/faq.php Device/Bus Power Management] FAQ and [http://www.lesswatts.org/tips/disks.php disks page]

* The ArchLinux [https://wiki.archlinux.org/index.php/Solid_State_Drives Solid State Drives] page

[[Category: Hardware]]

@@ Line 1: / Line 1: @@
+Serial ATA is specified by the [http://www.sata-io.org/ SATA International Organization]; the most current revision as of 2009-12-31 is June 2009's SATA 3.0. Intel specifies the [http://www.intel.com/technology/serialata/ahci.htm Advanced Host Controller Interface]; as of 2009-12-31, the most recent revision is 1.3 ([[:File:AHCIrev1_3.pdf]]). My [[growlight]] tool can provide a great deal of information about attached SATA devices.
+==SAS==
+An SFF-8087 connector can fan out to support up to 4 SATA devices.
+==SSDs==
+* Under ext4, the <tt>discard</tt> mount option must be provided to issue the TRIM command.
+* TRIM support can be verified using <tt>hdparm -I</tt> (look under "Commands/Features")
+** Btrfs doesn't require any option, supposedly. I don't yet use btrfs.
+* GPT is recommended over MBR
+* The <tt>noop</tt> I/O scheduler is supposedly superior to CFQ for some SSD's
+** <tt>echo noop | sudo tee /sys/block/sdX/queue/scheduler</tt>, but I find this highly dubious
+* Performance can drop after extensive use
+** Use the secure erase functionality to reset the drive: see [http://forums.extremeoverclocking.com/showthread.php?t=333059 this link] at ExtremeOverclockers
+** Again, [[growlight]] can help you here.
 ==Power Management==
-What is SATA Link Power Management (as seen in [[Power Management|powertop]] hints)?
+SATA's Aggressive Link Power Management [http://www.lesswatts.org/tips/disks.php ALPM], specified in SATA 1.x (in conjunction with AHCI-compliant controllers), effects [[Power Management|power savings]] at the serial link (this is independent of disk power management). There's both a "Partial" and "Suspend" mode; Suspend takes longer to enter/exit, and saves more power, than Partial.
 ==hddtemp==
@@ Line 96: / Line 110: @@
 ==SMART==
-There's more info on the [[SMART]] page.
+There's more general info on the [[SMART]] page. Generally, '-d ata' is a sufficient descriptor of a device for <tt>smartd</tt> to handle it. Determine [[SMART]] capability with <tt>smartctl -i</tt>:
-===Are my disks failing?===
-The one-line executive summary is available for supported disks via the <tt>-Hc</tt> option. <tt>grep</tt> for <tt>"^SMART overall"</tt> and verify <tt>PASSED</tt> as opposed to <tt>FAILING</tt>. If you're already <tt>FAILED</tt>, the command will generally fail in and of itself.
-===Details, for those interested===
-Generally, '-d ata' is a sufficient descriptor of a device for <tt>smartd</tt> to handle it. Determine [[SMART]] capability with <tt>smartctl -i</tt>:
 <pre>[recombinator](0) $ sudo smartctl -i /dev/sdc
 smartctl version 5.38 [x86_64-unknown-linux-gnu] Copyright (C) 2002-8 Bruce Allen
@@ Line 415: / Line 425: @@
 Checksum: correct
 [recombinator](0) $ </pre>
-==See Also==
+==See also==
-* "[http://www.linuxjournal.com/article/6983 Monitoring Hard Disks with SMART]", Linux Journal 2004-01-01
+* LessWatts.org [http://www.lesswatts.org/projects/devices-power-management/faq.php Device/Bus Power Management] FAQ and [http://www.lesswatts.org/tips/disks.php disks page]
+* The ArchLinux [https://wiki.archlinux.org/index.php/Solid_State_Drives Solid State Drives] page
+[[Category: Hardware]]

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