Mode Page Editor

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This is one of the most valuable components of S.M.A.R.T. Disk Monitor. It allows you to change hundreds of disk drive settings covering diverse features such as how the drive formats, power-saving settings, error-recovery algorithms, and read-write cache settings.


First and foremost ...

If you have no concept of what a mode page editor is, or what it can do for you, then look but do not touch. In extreme cases making incorrect changes can make your data inaccessible or result in data loss.


You should always consult with your hardware vendor to make sure any mode changes you make do not cause a problem and would be supportable. If you purchased your disk drives as part of an integrated system (particularly from Sun, HP, or SGI), the mode pages will typically be correct. They may, however, not be optimal for your hardware configuration. There are over a dozen configurable cache-related settings. By tweaking these values you may improve performance considerably.


If you purchased 3rd party disk drives, the mode pages will probably be incorrect. IBM, SUN, and HP may all integrate the same physical disk drive, but they have very different mode page settings for the error recovery and cache control pages.


For example, Seagate disks typically ship with write cache enabled, which will cause data loss if your system loses power. Sun and HP disks typically ship with write cache disabled for your protection.



To view all the mode pages for a particular device, enter:

/etc/smartmon-ux -A /hw/scsi/sc0d1l0


This might report something like:

SMARTMon-ux [Release 1.04, Build 27-SEP-2001] - Copyright 2001 SANtools, Inc.

Discovered SEAGATE ST39175LC S/N "3AL07K7P" on /hw/scsi/sc0d1l0 (S.M.A.R.T. enabled)


Page 00h Current:

0000: 80 02 07 00                                        ....

Page 00h Changeable:

0000: 80 02 77 40                                        ..w@

Page 00h Default:

0000: 80 02 00 00                                        ....

Page 00h Saved:

0000: 80 02 07 00                                        ....


Page 01h Current:

0000: 81 0A C4 0B E8 00 00 00 0F 00 FF FF                ............

Page 01h Changeable:

0000: 81 0A FF FF 00 00 00 00 FF 00 FF FF                ............

Page 01h Default:

0000: 81 0A C0 0B E8 00 00 00 0F 00 FF FF                ............

Page 01h Saved:

0000: 81 0A C4 0B E8 00 00 00 0F 00 FF FF                ............




Page 1Ch Current:

0000: 9C 0A 00 04 00 00 17 70 00 00 00 00                .......p....

Page 1Ch Changeable:

0000: 9C 0A 8D 0F FF FF FF FF FF FF FF FF                ............

Page 1Ch Default:

0000: 9C 0A 00 00 00 00 00 00 00 00 00 01                ............

Page 1Ch Saved:

0000: 9C 0A 08 00 00 00 00 00 00 00 00 01                ............

Terminating program.


If you then wanted to make a change to the saved page 1C, you might enter something like

/etc/smartmon-ux -B S,9C,0A,08,00,00,00,00,00,FF,FF,FF,FF /hw/scsi/sc0d1l0


Current, Saved, Default and Changeable Pages refer to the Page Control bits, which determine which set of values are desired. Basically consider the default settings are factory settings, and saved settings are the result of any changes that have been "saved" through SMARTMon-UX, or any other program which made a change to a particular mode page. If you make a change and specify it should be made to the saved page, that change will also be reflected into the current page.


Not all bits on all mode pages are changeable. Also, is it quite common for firmware upgrades to change changeable or default bits in particular mode pages. Furthermore, you might not be able to make any changes to a particular mode page for a particular device.


This manual does not contain the record layout and meanings of mode pages. This information is typically available from your disk manufacturer's web site, as a good portion of the pages are drive-specific.


Note also that mode pages are not unique to disk drives. They are unique, however to SCSI & Fibre channel devices. Tapes, CDROMs, disks, and some SES enclosures have mode pages.


If you have multiple mode pages to change, or want to clone some or all  mode pages to more than one peripheral of the same type, you should use the -mpimport and -mpexport functions found in the Batch Mode Page Import/Export section.