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I have recently installed Ubuntu 12.04 32 bit on a Lenovo X220, that is certified to work correctly with the OS (see here) including its default 128Gb SSD by Samsung. As soon as I got the laptop I have immediately upgraded to a Crucual M4-CT512M4SSD1 (7mm 512Gb) SSD that apparently works nicely but for what is described below. I hope you can give advice.

First of all, context:

giacecco@giaceccos-x220:~/Temp$ sudo hdparm -I /dev/sda | grep -e Model -e Firmware
[sudo] password for giacecco: 
Model Number: M4-CT512M4SSD1 
Firmware Revision: 000F 
giacecco@giaceccos-x220:~/Temp$ uname -a
Linux giaceccos-x220 3.2.0-27-generic-pae #43-Ubuntu SMP Fri Jul 6 15:06:05 UTC 2012 i686 i686 i386 GNU/Linux

AHCI is enabled in the BIOS. The laptop has a SATA 3 controller. The full disk is used for Ubuntu, and fully encrypted with LVM.

Then, basic performance indicators: see palimpsest's output here, hdparm below:

giacecco@giaceccos-x220:~/Temp$ sudo hdparm -Tt /dev/sda
/dev/sda:
Timing cached reads: 9664 MB in 2.00 seconds = 4834.41 MB/sec
Timing buffered disk reads: 1402 MB in 3.00 seconds = 466.81 MB/sec

Assuming hard disk encryption is not relevant, the SSD appears to be slow in respect to the 128Gb equivalent on cached reads but faster on timing buffered reads (according to some benchmarks on wiki.archlinux.org). I do not have sufficient understanding of SSD architecture to understand if this can be considered normal or not.

Finally, the actual issue. Whenever I suspend the laptop and I wake it back up I find this sequence in syslog:

(...)
Jul 24 07:34:14 giaceccos-x220 kernel: [20878.861152] ata1: link is slow to respond, please be patient (ready=0)
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.505379] ata1: COMRESET failed (errno=-16)
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.825130] ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.825701] ata1.00: ACPI cmd ef/02:00:00:00:00:a0 (SET FEATURES) succeeded
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.825704] ata1.00: ACPI cmd f5/00:00:00:00:00:a0 (SECURITY FREEZE LOCK) filtered out
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.825706] ata1.00: ACPI cmd ef/10:03:00:00:00:a0 (SET FEATURES) filtered out
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.826809] ata1.00: ACPI cmd ef/02:00:00:00:00:a0 (SET FEATURES) succeeded
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.826825] ata1.00: ACPI cmd f5/00:00:00:00:00:a0 (SECURITY FREEZE LOCK) filtered out
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.826827] ata1.00: ACPI cmd ef/10:03:00:00:00:a0 (SET FEATURES) filtered out
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.827353] ata1.00: configured for UDMA/100
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.841416] PM: resume of drv:sd dev:0:0:0:0 complete after 10366.217 msecs
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.841455] PM: resume of drv:scsi_disk dev:0:0:0:0 complete after 10331.031 msecs
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.841459] PM: resume of drv:scsi_device dev:0:0:0:0 complete after 10366.255 msecs
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.842748] hdaps: initial mode latch is 0x05
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.842883] hdaps: setting ec_rate=250, filter_order=2
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.843124] PM: resume of devices complete after 10368.491 msecs
Jul 24 07:34:14 giaceccos-x220 kernel: [20883.843365] PM: resume devices took 10.368 seconds
(...)

Of the lines above, the COMRESET one is loudly displayed on screen before I am offered to unlock the system.

The SSD appears to work normally anyway, Ubuntu appears responsive, but seeing the COMRESET lines on screen makes me wonder if I am doing anything wrong, or - worse - anything could break sooner or later, particularly if Ubuntu updated any drivers and that would not take it easy about the error.

What do you reckon? Thanks!

Giacecco

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1 Answer 1

The COMRESET line is simply a side-effect of the previous line in the log:

ata1: link is slow to respond, please be patient (ready=0)

If everything seems to be working fine, all that means is that the device (SSD) takes a few seconds to "wake up", and impatient Ubuntu spits out warnings.

The very next line shows that the device wakes up half-a-second after the warning:

ata1: SATA link up 6.0 Gbps (SStatus 133 SControl 300)

All in all, no problems and nothing to worry about. Cached reads are a synthetic benchmark and your rate is certainly speedy enough; naturally, at 5 GB/sec you may be limited by the full disk encryption. The buffered reads are what matter and they are way up there :)

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