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Rev 1.6: auto '-d sat', background scan, windows device names 

git-svn-id: https://smartmontools.svn.sourceforge.net/svnroot/smartmontools/trunk@2303 4ea69e1a-61f1-4043-bf83-b5c94c648137
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......@@ -22,15 +22,23 @@ ps, txt, etc.
</affiliation>
</author>
<authorinitials>dpg</authorinitials>
<pubdate>2006-06-24</pubdate>
<pubdate>2006-10-22</pubdate>
<revhistory>
<revision>
<revnumber>1.6</revnumber>
<date>2006-10-22</date>
<authorinitials>dpg</authorinitials>
<revremark>
auto '-d sat', background scan, windows device names
</revremark>
</revision>
<revision>
<revnumber>1.5</revnumber>
<date>2006-06-24</date>
<authorinitials>dpg</authorinitials>
<revremark>
device type sat
device type 'sat'
</revremark>
</revision>
<revision>
......@@ -101,13 +109,13 @@ ps, txt, etc.
<abstract>
<para>
This article describes how smartmontools interacts with SCSI
storage devices (including tapes). Smartmontools is a SMART
This article describes how smartmontools interacts with SCSI storage
devices (mainly hard disks and tape drives). Smartmontools is a SMART
utility toolset. <acronym>SMART</acronym> is an acronym for
Self-Monitoring, Analysis and Reporting Technology. Smartmontools
is available for the these operating systems: Darwin (Mac OS X
but with no SCSI support yet), FreeBSD, Linux, NetBSD, OpenBSD,
Solaris and Windows.
OS/2 (no SCSI support), Solaris and Windows.
</para>
</abstract>
</articleinfo>
......@@ -123,8 +131,8 @@ Smartmontools controls and monitors storage devices using the
Self-Monitoring, Analysis and Reporting Technology
(<acronym>SMART</acronym>) system. This toolset was originally built
for the Linux operating system and has been ported to Darwin for
Mac OS X (no SCSI support yet), FreeBSD, NetBSD, OpenBSD, Solaris
and Windows.
Mac OS X (no SCSI support yet), FreeBSD, NetBSD, OpenBSD,
OS/2 (no SCSI support), Solaris and Windows.
This article describes how smartmontools interacts with SCSI devices.
Passing reference is also made to devices that use the SCSI command
set such as USB mass storage devices and IEEE1394 devices that use
......@@ -137,15 +145,15 @@ The primary web site for smartmontools is at
<literal>smartmontools.sourceforge.net</literal></ulink> from which the
latest versions (both source and binaries) can be obtained. Smartmontools
grew out of the now dormant <emphasis>smartsuite</emphasis> project which
is still available on its sourceforge site. The smartmontools main page
is still available on its own sourceforge site. The smartmontools main page
concentrates on ATA devices.
This article supplies some SCSI specific information for
those users of smartmontools that wish to monitor SCSI storage devices.
</para>
<para>
This document outlines the features found in smartmontools
version 5.38 that are relevant to SCSI disks and tape drives.
This document was last altered on 24th May 2006.
version 5.37 that are relevant to SCSI disks and tape drives.
This document was last altered on 22nd October 2006.
</para>
</sect1>
......@@ -188,8 +196,17 @@ pending failures are reported.
<title>Operating Systems</title>
<para>
Smartmontools was originally written for Linux. Since then it has been
ported to various other Unix based system and Windows. The names of
SCSI disk and tape devices vary. Here is a summary:
ported to various other Unix based systems and Windows. Note that the
device names are based on the transport that an operating system sees.
These days it is not uncommon for an operating system to see a
transport that only conveys SCSI commands connected, via some command
translation bridge, to an ATA disk. Examples are USB external disk
enclosures and SATA disks behind a SCSI to ATA Translation Layer (SATL)
in a SAS or FC domain.
</para>
<para>
The names of SCSI disk and tape devices vary with the operating system.
Here is a summary:
<table frame="all"><title>SCSI device names in various systems</title>
<tgroup cols="4" align="left" colsep="1" rowsep="1">
......@@ -214,8 +231,13 @@ SCSI disk and tape devices vary. Here is a summary:
</row>
<row>
<entry><command>NetBSD</command></entry>
<entry><filename>/dev/sd[0-9]</filename></entry>
<entry><filename>/dev/enrst[0-9]</filename></entry>
<entry><filename>/dev/sd[0-9]+c</filename></entry>
<entry><filename>/dev/st[0-9]+c</filename></entry>
</row>
<row>
<entry><command>OpenBSD</command></entry>
<entry><filename>/dev/sd[0-9]+c</filename></entry>
<entry><filename>/dev/st[0-9]+c</filename></entry>
</row>
<row>
<entry><command>Solaris</command></entry>
......@@ -226,15 +248,44 @@ SCSI disk and tape devices vary. Here is a summary:
<entry><command>Windows</command></entry>
<entry><filename>/dev/scsi[0-9][0-f]</filename></entry>
<entry><filename>/dev/scsi[0-9][0-f]</filename></entry>
<entry>ASPI adapter:0-9, ID:0-15, <filename>/dev/</filename> optional
</entry>
<entry>ASPI adapter:0-9, ID:0-15</entry>
</row>
<row>
<entry/>
<entry><filename>/dev/sd[a-z]</filename></entry>
<entry/>
<entry>for '\\.\PhysicalDrive[0-25]'</entry>
</row>
<row>
<entry/>
<entry><filename>/dev/pd[0-255]</filename></entry>
<entry/>
<entry>for '\\.\PhysicalDrive[0-255]'</entry>
</row>
<row>
<entry/>
<entry/>
<entry><filename>/dev/tape[0-255]</filename></entry>
<entry>for '\\.\Tape[0-255]'</entry>
</row>
<row>
<entry><command>Darwin</command></entry>
<entry/>
<entry/>
<entry>no support for SCSI devices</entry>
</row>
<row>
<entry><command>OS/2</command></entry>
<entry/>
<entry/>
<entry>no support for SCSI devices</entry>
</row>
</tbody>
</tgroup>
</table>
</para>
<para>
The above list is a simplification of course. In Linux there can be multiple
The above list is a simplification. In Linux there can be multiple
drive letters followed by a partition number (1 to 15). Smartmontools will
ignore the partition number if it is given and query the underlying device.
In Linux the SCSI tape device name can be "nst" and a letter can be
......@@ -246,7 +297,7 @@ be accessed via their generic name which is of the form
<para>
Linux also has an optional Solaris like
naming scheme for SCSI device (scsidev), devfs (mainly used in the lk 2.4
series) and udev (its replacement in the lk 2.6 series). In short, device
series) and udev (devfs's replacement in the lk 2.6 series). In short, device
naming is a complex area and smartmontools does its best to find
and identify (i.e. whether ATA or SCSI) a device depending on its name. In
some cases smartmontools needs guidance from the user and this can be given
......@@ -254,6 +305,13 @@ by the '-d ata|scsi|sat|marvell|3ware,N' option in the
<command>smartctl</command> utility and in <command>smartd</command>
daemon's configuration file.
</para>
<para>
Windows has several schemes for naming devices. The "scsi[0-9][0-f]" scheme
uses the aspi dll from Adaptec. That dll is not distributed with Windows. The
other schemes use the "SCSI Pass Through" interface which is native to
Windows in NT and later. In all cases for Windows, the leading
<filename>/dev/</filename> is optional.
</para>
</sect1>
<sect1 id="scsidisk">
......@@ -305,20 +363,24 @@ SCSI command.
</para>
<para>
There is an emerging SCSI to ATA Translation (SAT) standard
at <ulink url="http://www.t10.org"> <literal>www.t10.org</literal></ulink>
at <link linkend="t10">www.t10.org</link>
that may lead to improvements in this area. Apart from defining
some of the facilities smartmontools needs, it defines two ATA PASS THROUGH
SCSI commands. These pass through commands could be used in much the
same way that the 3ware RAID tunnels ATA commands.
</para>
<para>
In order for smartmontools to access an ATA device "behind" a SAT layer
that implements either of the ATA PASS THROUGH SCSI commands, a new device
type called '-d sat' has been introduced. For example this command:
<command>smartctl -a -d sat /dev/sda</command> will form ATA commands
to access various SMART attributes of an ATA disk, then package those
commands within ATA PASS THROUGH SCSI commands and then forward them
to the SCSI interface of <filename>/dev/sda</filename>.
The device type '-d sat' instructs the <command>smartctl</command>
command and the <command>smartd</command> daemon, to form SMART
commands for the ATA command set and then package those commands
within the ATA PASS THROUGH SCSI commands. The SCSI commands
are then sent to the "SCSI" device that the operating system
has been given. In version 5.37 of smartmontools it is no longer
necessary to specify '-d sat' in this situation. All that is
needed is a SATL that complies with the emerging SAT standard.
If the automatic detection of an ATA disk behind a SATL is
tricked, '-d scsi' (or some other device type) can be used to
override.
</para>
<para>
It has been reported that many external USB enclosures use a "Cypress"
......@@ -396,7 +458,7 @@ associated with a SAS expander)
</itemizedlist>
</para>
<para>
For normal file system work, a SCSI to ATA (SAT) translation layer only
For normal file system work, a SCSI to ATA Translation Layer (SATL) only
needs to concern itself with around 6 commands. Unfortunately
smartmontools uses other commands (both in the SCSI and ATA
command sets). Probably the simplest way to handle SMART for SATA disks
......@@ -419,10 +481,9 @@ guess made by smartmontools can be overridden. The '-d sat' device
type causes smartmontools to generate ATA commands which are then packaged
within the ATA PASS THROUGH SCSI commands (defined by the SAT standard)
and then sent to the device via a SCSI pass through mechanism.
Future versions of smartmontools may automate the detection of a "SATA
disk behind a SAT layer" but currently if a SATA disk appears
with a SCSI type device node name then a command like this may be
required: <command>smartctl -a -d sat /dev/sda</command> .
As noted in the previous section, version 5.37 of smartmontools now
automatically detects a SATA disk behind a SAT layer and acts as
if '-d sat' has been given.
</para>
</sect1>
......@@ -452,11 +513,10 @@ lists the supported mode pages with their default and changeable values.
</para></footnote>
</para>
<para>
SCSI standards (found at <ulink url="http://www.t10.org">
<literal>www.t10.org</literal></ulink>) only make one footnote
reference to the term <acronym>SMART</acronym>. In its place
the awkward term "Informational Exceptions" is used. For SCSI tapes the term
"TapeAlert" is used.
SCSI standards (found at <link linkend="t10">www.t10.org</link>)
only make one footnote reference to the term <acronym>SMART</acronym>.
In its place the awkward term "Informational Exceptions" is used. For SCSI
tapes the term "TapeAlert" is used.
</para>
</sect1>
......@@ -471,8 +531,8 @@ has many options that can be viewed by the long usage message output be
either of these invocations: <command>smartctl -h</command> or
<command>smartctl --help</command>. Those options that are only
available to ATA disks (i.e. not available to SCSI disks or tape drives)
are marked with "(ATA)". So called "man" page documentation is also
available online.
are marked with "(ATA)". Unix style "man" page documentation is also
available.
</para>
<para>
The following options are currently available for SCSI disks and tape
......@@ -484,7 +544,7 @@ invoked in that order.
</para></listitem>
<listitem><para><command>-A | --attributes</command>: outputs the
current device temperature, trip temperature, the number of elements
in the grown defect table and data from the start-stop log page.
in the grown defect list (GLIST) and data from the start-stop log page.
Outputs some vendor specific information if available.
</para></listitem>
<listitem><para><command>-C | --captive</command>: used in conjunction
......@@ -493,9 +553,9 @@ do short or long self tests in the foreground. [Has no effect on tape
drives.]
</para></listitem>
<listitem><para><command>-d TYPE | --device=TYPE</command> where TYPE
is "ata", "scsi", "marvell" or "3ware,N". Overrides utility's guess
about the class of the device which is based on the form of the nominated
device's name.
is "ata", "scsi", "sat", "marvell", "3ware,N", "hpt,L/N[,M]"
or "cciss,N". Overrides utility's guess about the class of the device
which is based on the form of the nominated device's name.
</para></listitem>
<listitem><para><command>-h | --help</command>: outputs lengthy usage
message and exits without any other action.
......@@ -512,8 +572,9 @@ type of transport (e.g. FC or SAS) is also reported, if available.
Some users have reported disks that report the wrong transport.
</para></listitem>
<listitem><para><command>-l TYPE | --log=TYPE</command> where TYPE is
either "selftest" or "error". Outputs either the selftest log or the
error log.
either "background", "selftest" or "error". Decodes are outputs the
requested log. Note that <command>--all</command> does not include
<command>--log=background</command> .
</para></listitem>
<listitem><para><command>-q TYPE | --quietmode=TYPE</command> where TYPE is
either "silent" or "errorsonly". When the type is silent then nothing is
......@@ -865,6 +926,79 @@ purpose (by writing a bad sector with the SCSI WRITE LONG command).
</para>
</sect1>
<sect1 id="background">
<title>Background scan</title>
<para>
Recent SCSI disks can perform what are termed as "background scans". These
are reads of the whole media with recoverable errors acted on and
unrecoverable errors noted. If a sector (block) is found with a recoverable
error (i.e. the error correction codes (ECC) detect a problem but contain
enough redundant information to fix the problem) it may be fixed with a
re-write "in place". Alternatively the disk may decide to re-assign the
recovered data to another physical sector which is assigned the same logical
block address (and the original faulted sector is unmapped and placed on
the grown defect list (GLIST)). Since unrecoverable errors potentially
involve user data being lost, no automatic recovery action is undertaken by
the disk. However logical block addresses that contain either recovered
data or unrecoverable errors are noted in the Background Scan Results
log page. The <command>smartctl --log=background</command> command decodes
and outputs that log page.
</para>
<para>
Background scans may be performed periodically (e.g. every 24 hours) or
every time the disk is powered up (or both). These parameters can be
controlled via the Background Control mode page. The
<link linkend="sdparm">sdparm</link> utility can be used to access and
modify this mode page.
</para>
<para>
Here is an example of the output from the Background Scan Results log page.
The first descriptor in that log page shows the status followed by up
to 2048 entries for background scan "events". In this case a background
scan is still in progress and 3 scans have been completed in the past.
The "events" shown are all recoverable errors that the disk dealt with
by rewriting the block.
<programlisting>
# smartctl -l background /dev/sda
smartctl version 5.37 [i686-pc-linux-gnu] Copyright (C) 2002-6 Bruce Allen
Home page is http://smartmontools.sourceforge.net/
Background scan results log
Status: scan is active
Accumulated power on time, hours:minutes 618:01 [37081 minutes]
Number of background scans performed: 3, scan progress: 59.81%
# when lba(hex) [sk,asc,ascq] reassign_status
1 617:13 0000000001fbc5b2 [1,17,1] Recovered via rewrite in-place
2 617:13 00000000022756d2 [1,17,1] Recovered via rewrite in-place
3 617:14 000000000227727f [1,17,1] Recovered via rewrite in-place
4 617:18 00000000023568e5 [1,17,1] Recovered via rewrite in-place
5 617:22 00000000024fab5f [1,17,1] Recovered via rewrite in-place
6 617:23 00000000025aa29a [1,17,1] Recovered via rewrite in-place
7 617:27 000000000275d0bc [1,17,1] Recovered via rewrite in-place
</programlisting>
In this case the reassign_status shows that no user intervention is
required. The other "don't worry (too much)" reassign_status is "Logical
block successfully reassigned". Any other reassign_status will require
user intervention to correct. There is a LOWIR ("log only when intervention
required") bit in the Background Control mode page that the user can
set (e.g. with the <link linkend="sdparm">sdparm</link> utility) to filter
out "noisy" entries like those shown above.
</para>
<para>
The user can manually re-assign logical blocks with a utility like
<command>sg_reassign</command> found in the
<link linkend="sg3utils">sg3_utils</link> package. The background scan
output contains a "[sk,asc,ascq]" tuple of numbers. The one shown above
translates to "recovered error, recovered data with retries". Unrecoverable
errors would most likely have 3 ("medium eror") or 4 ("hardware error")
as the first number. A decoding of the latter two numbers can be found
in the "Numeric Order Codes" annex of SPC-4 (see <link linkend="t10">
www.t10.org</link>) in the Additional Sense Codes section.
</para>
</sect1>
<sect1 id="smartd">
<title>smartd daemon</title>
<para>
......@@ -900,7 +1034,9 @@ named explicitly:
/dev/sdb -d scsi
</programlisting>
The "-d scsi" argument overrides what <command>smartd</command> would
guess as the device class (i.e. "ata", "scsi", "marvell" or "3ware,N").
guess as the device
class (i.e. "ata", "scsi", "sat", "marvell", "3ware,N", "hpt,L/N[,M]"
or "cciss,N").
</para>
</sect1>
......@@ -1022,11 +1158,9 @@ Quantum ATLAS IV 36 WLS, 36 GigaByte
<literal>disk</literal></ulink>
</para></listitem>
<listitem><para>
Seagate Cheetah ST318451LW 18 GigaByte
<ulink url="examples/st318451_smt_a.html">
<literal>disk</literal></ulink>. It would seem that the total count of bytes
written is reset every time the disk is power cycled. However the total
count of bytes read seems to accumulate over power cycles.
Seagate Cheetah ST336754 36 GigaByte
<ulink url="examples/st336754_smt_a.html">
<literal>disk</literal></ulink>.
</para></listitem>
</itemizedlist>
......@@ -1067,12 +1201,11 @@ to collectively monitor and manage a group of disks and/or tape
drives (be they a RAID, "Just a Bunch Of Disks" <acronym>JBOD</acronym>
or a collection of disks and tape drives) in an enclosure. The SCSI
Enclosure Services <acronym>SES</acronym> (reference: SES-2 at
<ulink url="http://www.t10.org"> <literal>www.t10.org</literal></ulink>)
is designed for this task. Both SCSI device and recent SATA disk
enclosures are using SES. Amongst other things SES can monitor the state
of individual devices within the enclosure, the temperature, power
supplies and fans. A user can set thresholds, define alarm types and
remotely administer the enclosure.
<link linkend="t10">www.t10.org</link>) is designed for this task.
Both SCSI device and recent SATA disk enclosures are using SES. Amongst
other things SES can monitor the state of individual devices within the
enclosure, the temperature, power supplies and fans. A user can set
thresholds, define alarm types and remotely administer the enclosure.
</para>
</sect1>
......@@ -1082,10 +1215,9 @@ remotely administer the enclosure.
<title>Standards</title>
<para>
One of the first surprises working with SCSI devices and smartmontools
is that the SCSI standards (found at <ulink url="http://www.t10.org">
<literal>www.t10.org</literal></ulink>) do <emphasis>not</emphasis> use
the term <acronym>SMART</acronym>. In its place the awkward term "Informational
Exceptions" (IE) is used.
is that the SCSI standards (found at <link linkend="t10">www.t10.org</link>)
do <emphasis>not</emphasis> use the term <acronym>SMART</acronym>. In its
place the awkward term "Informational Exceptions" (IE) is used.
</para>
<para>
The original SCSI standard (over 20 years old now) and the SCSI-2 standard
......@@ -1294,9 +1426,14 @@ Here are some links to related projects and packages:
<itemizedlist>
<listitem><para>
<anchor id="t10"/>
primary reference site for SCSI architecture, command sets and transports
<ulink url="http://www.t10.org">
<literal>www.t10.org</literal></ulink>.
the primary reference site for SCSI architecture, command sets and transports
is <ulink url="http://www.t10.org">
<literal>www.t10.org</literal></ulink>. The main documents of interest
to smartmontools are the "Primary Commands" (SPC-4), the "Block
Commands" (SBC-3) for disks and the "Streaming Commands" (SSC-3) for
tape drives. This <ulink url="http://www.t10.org/scsi-3.htm">
<literal>www.t10.org/scsi-3.htm</literal></ulink> page contains a diagram
showing the relationships of various SCSI standards.
<footnote><para>
The documents found on the t10 site are actually <emphasis>draft</emphasis>
standards. Once they are ratified they become available from ANSI for
......@@ -1316,17 +1453,18 @@ The <command>sdparm</command> utility allows mode page settings to be
viewed and changed. It can decode Vital Product Data (VPD) pages.
It implements a small number of commands to start and stop media,
and to eject and load removable media.
on this page <ulink url="http://www.torque.net/sg/sdparm.html">
See this page <ulink url="http://www.torque.net/sg/sdparm.html">
<literal>www.torque.net/sg/sdparm.html</literal></ulink> .
<command>sdparm</command> is available on Linux with ports to
FreeBSD and Tru64.
FreeBSD, Tru64 and Windows.
</para></listitem>
<listitem><para>
<anchor id="sg3utils"/>
A package of SCSI low level tools for Linux called sg3_utils can be found
on this page <ulink url="http://www.torque.net/sg/u_index.html">
<literal>www.torque.net/sg/u_index.html</literal></ulink> (the most recent
version is sg3_utils-1.20). Allows command level access to SCSI devices.
on this page <ulink url="http://www.torque.net/sg/sg3_utils.html">
<literal>www.torque.net/sg/sg3_utils.html</literal></ulink> (the most recent
version is sg3_utils-1.22). Allows command level access to SCSI devices
and is available on Linux with ports to FreeBSD, Tru64 and Windows.
</para></listitem>
<listitem><para>
<anchor id="howto"/>
......@@ -1338,7 +1476,7 @@ There is a HOWTO on the Linux SCSI subsystem in the 2.4 series here:
</para>
<para>
CVS $Id: smartmontools_scsi.xml,v 1.14 2006/06/24 13:05:58 dpgilbert Exp $
CVS $Id: smartmontools_scsi.xml,v 1.15 2006/10/23 01:16:31 dpgilbert Exp $
</para>
</sect1>
</appendix>
......
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