Hm, that means "rtcwake -m mem -s 30" somehow failed. Can you please run this in an endless loop until it fails and then grab the error code and output?

# while rtcwake -m mem -s 30 ; do echo suceeded $? ; done ; echo failed $?

output:
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:28:20 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:28:55 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:29:30 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:30:05 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:30:40 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:31:15 2013
suceeded 0
rtcwake: wakeup from "mem" using /dev/rtc0 at Tue Aug 20 06:31:50 2013
rtcwake.sh: line 1:  4146 Segmentation fault      (core dumped) rtcwake -m mem -s 30
failed 0

error:
traps: rtcwake[4146] general protection ip:4dd1a9a8 sp:bffdd380 error:0 in libc-2.15.so[4dcaa000+1ab000]

Created attachment 84301 [details]
rtcwake dmesg

That's just a bug in rtcwake, and it seems to work fine here. On a quick check libc2.15 is about 1 year old, so can you pls try to upgrade your distro?

output:
rtcwake: wakeup from "mem" using /dev/rtc0 at Wed Aug 21 07:36:38 2013
rtcwake: write error
failed 0

 Call Trace:
[  146.353026]  [<ffffffff8104ea7d>] ? up+0xb/0x36
[  146.353047]  [<ffffffff810c8f74>] ? dma_pool_alloc+0x1a0/0x1c4
[  146.353074]  [<ffffffff815d365c>] ? uhci_alloc_td.isra.30+0x13/0x45
[  146.353100]  [<ffffffff810c8f74>] ? dma_pool_alloc+0x1a0/0x1c4
[  146.353130]  [<ffffffff816efc5e>] ? schedule_timeout+0x147/0x16d
[  146.353156]  [<ffffffff8103c198>] ? usleep_range+0x3e/0x3e
[  146.353180]  [<ffffffff816f1a85>] ? wait_for_common+0x119/0x146
[  146.353209]  [<ffffffff81053d82>] ? try_to_wake_up+0x1e3/0x1e3
[  146.353235]  [<ffffffff815b7f95>] ? usb_start_wait_urb+0x7b/0xc7
[  146.353263]  [<ffffffff813604f7>] ? dev_printk_emit+0x39/0x3e
[  146.353287]  [<ffffffff815b81f0>] ? usb_control_msg+0xc6/0xfb
[  146.353315]  [<ffffffff815b1268>] ? hub_port_init+0x37b/0x85d
[  146.353339]  [<ffffffff815b3a1d>] ? hub_thread+0x7cb/0xdf4
[  146.353364]  [<ffffffff81050d82>] ? __wake_up_common+0x42/0x78
[  146.353389]  [<ffffffff8104b8a8>] ? abort_exclusive_wait+0x79/0x79
[  146.353417]  [<ffffffff815b3252>] ? hub_port_debounce+0xcf/0xcf
[  146.353444]  [<ffffffff8104afca>] ? kthread+0xad/0xb5
[  146.353466]  [<ffffffff8104af1d>] ? kthread_freezable_should_stop+0x40/0x40
[  146.353496]  [<ffffffff816f7e6c>] ? ret_from_fork+0x7c/0xb0
[  146.353523]  [<ffffffff8104af1d>] ? kthread_freezable_should_stop+0x40/0x40

[  146.353563] Restarting kernel threads ... done.
[  146.353695] Restarting tasks ... done.

Created attachment 84369 [details]
rtc dmesg

(In reply to comment #5)
> output:
> rtcwake: wakeup from "mem" using /dev/rtc0 at Wed Aug 21 07:36:38 2013
> rtcwake: write error
> failed 0
> 
>  Call Trace:
> [  146.353026]  [<ffffffff8104ea7d>] ? up+0xb/0x36
> [  146.353047]  [<ffffffff810c8f74>] ? dma_pool_alloc+0x1a0/0x1c4
> [  146.353074]  [<ffffffff815d365c>] ? uhci_alloc_td.isra.30+0x13/0x45
> [  146.353100]  [<ffffffff810c8f74>] ? dma_pool_alloc+0x1a0/0x1c4
> [  146.353130]  [<ffffffff816efc5e>] ? schedule_timeout+0x147/0x16d
> [  146.353156]  [<ffffffff8103c198>] ? usleep_range+0x3e/0x3e
> [  146.353180]  [<ffffffff816f1a85>] ? wait_for_common+0x119/0x146
> [  146.353209]  [<ffffffff81053d82>] ? try_to_wake_up+0x1e3/0x1e3
> [  146.353235]  [<ffffffff815b7f95>] ? usb_start_wait_urb+0x7b/0xc7
> [  146.353263]  [<ffffffff813604f7>] ? dev_printk_emit+0x39/0x3e
> [  146.353287]  [<ffffffff815b81f0>] ? usb_control_msg+0xc6/0xfb
> [  146.353315]  [<ffffffff815b1268>] ? hub_port_init+0x37b/0x85d
> [  146.353339]  [<ffffffff815b3a1d>] ? hub_thread+0x7cb/0xdf4
> [  146.353364]  [<ffffffff81050d82>] ? __wake_up_common+0x42/0x78
> [  146.353389]  [<ffffffff8104b8a8>] ? abort_exclusive_wait+0x79/0x79
> [  146.353417]  [<ffffffff815b3252>] ? hub_port_debounce+0xcf/0xcf
> [  146.353444]  [<ffffffff8104afca>] ? kthread+0xad/0xb5
> [  146.353466]  [<ffffffff8104af1d>] ?
> kthread_freezable_should_stop+0x40/0x40
> [  146.353496]  [<ffffffff816f7e6c>] ? ret_from_fork+0x7c/0xb0
> [  146.353523]  [<ffffffff8104af1d>] ?
> kthread_freezable_should_stop+0x40/0x40
> 
> [  146.353563] Restarting kernel threads ... done.
> [  146.353695] Restarting tasks ... done.

Ok, doesn't look so much like a bug in rtcwake but an usb issue - somehow probing of one of the usb devices you have fails while running suspend/resume, which then fails the entire suspend process. So rtcwake actually seems to work and correctly report the error back!

For debugging the usb issue I'd try to unplug everything you have plugged in and retest. If that works then figure out which usb devices is the offender and throw that one into the bin. If that doesn't help I think you need to file a kernel bug against the usb subsystem and maybe ping Sarah Sharp about this.

In any case this is not our bug ...