Ubuntu: Suspend does not work on Dell T20 with 16.04


I installed Ubuntu 16.04 on my Dell T20. However I cannot get suspend to work properly (really saving energy). I know the hardware can suspend as another Dell running Windows does suspend properly. The command I am using is "systemctl suspend", but the result is "freeze" instead of "mem", i.e. disks spin down, system does no longer react to input, but power consumption still close to active. I also tried "pm-suspend" which does nothing at all. A cat /sys/power/state shows just freeze and disk, no mem.

I do have dmesg output with debugging info, but it does not fit the 30000 characters limit, and also I cannot see a real error there. I also looked at: https://wiki.ubuntu.com/UnderstandingSuspend - but /etc/acpi/sleep.sh does not exist. Is this specific to an older version? https://01.org/blogs/rzhang/2015/best-practice-debug-linux-suspend/hibernate-issues - the line "ACPI: (supports S0 S3 S4 S5)" is missing, but is Ubuntu kernel compiled without suspend support?

Any suggestion?

Thanks & Best regards, Joachim


This question may be old, but still be interesting for future readers: Dell T20 supports S3 by design: http://downloads.dell.com/manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-t20_reference%20guide_en-us.pdf

However, S3 can be blocked in BIOS. Boot into BIOS Configuration and make sure, you've not blocked S3. Also, there is a bug in recent BIOS versions, which prevents S3 from working (also true for Windows). Simply downgrade your Dell T20 to A05 BIOS and you're good to go. At the date of writing, there are no newer BIOSes, which work with S3, namely A06, A09 and A10.

Cheers, Tolga


According to the T20 technical guide, this server cannot suspend.

Supported states: S0 (Working), S4-OS (‘Hibernation’), and S5 (Soft-off). S1 (also called ‘standby’ or ‘suspend’) and S3 are not supported.

Any idea what the difference is between hibernate and soft-off?

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