SanDisk Extreme Pro® SSD

[allistar]

Hi there,

  I recently purchased an ExtremePro 240Gb. The computer it's going in is an ASUS P5B deluxe. The drive is plugged into a 6Gb/s SATA card (a Rocket 620A Dual Port PCI-Express adapter). This adapter is plugged into a PCI-ex4 slot. The BIOS is using AHCI mode for SATA disks. I run Gentoo linux.

I have formatted the SSD into two Ext4 partitions (one 64Mb and the other is the remaining). Hdparm reveals this:

hdparm -tT /dev/sde
/dev/sde:
 Timing cached reads:   7312 MB in  2.00 seconds = 3659.09 MB/sec
 Timing buffered disk reads: 576 MB in  3.00 seconds = 191.84 MB/sec

Smartctl reveals this:

smartctl -a /dev/sde

smartctl 6.4 2015-06-04 r4109 [x86_64-linux-4.4.6-gentoo] (local build)
Copyright (C) 2002-15, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Marvell based SanDisk SSDs
Device Model:     SanDisk SDSSDXPS240G
Serial Number:    154242402021
LU WWN Device Id: 5 001b44 ef52542e5
Firmware Version: X21200RL
User Capacity:    240,057,409,536 bytes [240 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Form Factor:      2.5 inches
Device is:        In smartctl database [for details use: -P show]
ATA Version is:   ACS-2 T13/2015-D revision 3
SATA Version is:  SATA 3.2, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Thu May 26 11:32:34 2016 NZST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

General SMART Values:
Offline data collection status:  (0x00) Offline data collection activity
                                        was never started.
                                        Auto Offline Data Collection: Disabled.
Self-test execution status:      (   0) The previous self-test routine completed
                                        without error or no self-test has ever 
                                        been run.
Total time to complete Offline 
data collection:                (    0) seconds.
Offline data collection
capabilities:                    (0x11) SMART execute Offline immediate.
                                        No Auto Offline data collection support.
                                        Suspend Offline collection upon new
                                        command.
                                        No Offline surface scan supported.
                                        Self-test supported.
                                        No Conveyance Self-test supported.
                                        No Selective Self-test supported.
SMART capabilities:            (0x0003) Saves SMART data before entering
                                        power-saving mode.
                                        Supports SMART auto save timer.
Error logging capability:        (0x01) Error logging supported.
                                        General Purpose Logging supported.
Short self-test routine 
recommended polling time:        (   2) minutes.
Extended self-test routine
recommended polling time:        (  10) minutes.

SMART Attributes Data Structure revision number: 4
Vendor Specific SMART Attributes with Thresholds:
ID# ATTRIBUTE_NAME          FLAG     VALUE WORST THRESH TYPE      UPDATED  WHEN_FAILED RAW_VALUE
  5 Reallocated_Sector_Ct   0x0032   100   100   ---    Old_age   Always       -       0
  9 Power_On_Hours          0x0032   002   100   ---    Old_age   Always       -       2
 12 Power_Cycle_Count       0x0032   100   100   ---    Old_age   Always       -       2
166 Min_W/E_Cycle           0x0032   100   100   ---    Old_age   Always       -       0
167 Min_Bad_Block/Die       0x0032   100   100   ---    Old_age   Always       -       24
168 Maximum_Erase_Cycle     0x0032   100   100   ---    Old_age   Always       -       1
169 Total_Bad_Block         0x0032   100   100   ---    Old_age   Always       -       398
171 Program_Fail_Count      0x0032   100   100   ---    Old_age   Always       -       0
172 Erase_Fail_Count        0x0032   100   100   ---    Old_age   Always       -       0
173 Avg_Write/Erase_Count   0x0032   100   100   ---    Old_age   Always       -       0
174 Unexpect_Power_Loss_Ct  0x0032   100   100   ---    Old_age   Always       -       0
184 End-to-End_Error        0x0032   100   100   ---    Old_age   Always       -       0
187 Reported_Uncorrect      0x0032   100   100   ---    Old_age   Always       -       0
188 Command_Timeout         0x0032   100   100   ---    Old_age   Always       -       0
194 Temperature_Celsius     0x0022   064   038   ---    Old_age   Always       -       36 (Min/Max 25/38)
199 SATA_CRC_Error          0x0032   100   100   ---    Old_age   Always       -       0
212 SATA_PHY_Error          0x0032   100   100   ---    Old_age   Always       -       0
230 Perc_Write/Erase_Count  0x0032   100   100   ---    Old_age   Always       -       0
232 Perc_Avail_Resrvd_Space 0x0033   100   100   004    Pre-fail  Always       -       100
233 Total_NAND_Writes_GiB   0x0032   100   100   ---    Old_age   Always       -       12
241 Total_Writes_GiB        0x0030   253   253   ---    Old_age   Offline      -       11
242 Total_Reads_GiB         0x0030   253   253   ---    Old_age   Offline      -       3
244 Thermal_Throttle        0x0032   000   100   ---    Old_age   Always       -       0

SMART Error Log Version: 1
No Errors Logged

SMART Self-test log structure revision number 1
No self-tests have been logged.  [To run self-tests, use: smartctl -t]

Selective Self-tests/Logging not supported

That shows that TRIM is enabled and that it's in 6Gb/s mode.

Question: what is causing this new SSD to perform so slowly? What can I look at to diagnose this issue?

[Chushi]

Hi allistar,

Yes the speed seems slow, there may be various reasons to it, maybe the PCIe adaptor, the driver or even the drive its self etc.

We have never tested a PCIe adapter for this drive, if you want, I can forward this information to our development and have them take a look, but please send the full system info too.

Please note, due to bandwidth reasons, there is no ETA on when will they get back on this.

[allistar]

The reason I'm using a PCIe adapter for SATA is that it's 6Gb/s while the build in SATA on the motherboard is only 3Gb/s. I will try the SSD on the motherboard SATA headers to see if it makes a difference, but I can't see it being any faster.

The relevant specs for this computer are:

ASUS P5B deluxe

Processor: Intel QX6700 (quad core 2.6GHz)
6Gb 800MHz SDRAM

PCIe card: Highpoint Rocket 620A plugged into a PCIe-x4 port, though it's only a x1 card.

I have not installed any specific drivers for this drive or the controller. It just works. I am using an Ext4 filesystem on the SSD, though that shouldn't be relevant to the speed test as that's done on the drive itself, not the partition.

What else do you need to know?

[Chushi]

There are variety of reasons of a performance drop, is your PCIe port NVMe or SATA ? If you connect a SATA device to PCIe port with an adaptor, there's no gurantee of the performance you will be getting, because the product is not designed to work that way, and I have no idea what the adaptor does during transfering signal, so my suggestion would be find a SATAIII port and re-test about speed.

I understand the drive works under your current driver, but drivers may cause the drive is not up to full speed too, that's the reason I want you to update the drivers

[allistar]

The motherboard is quite old so doesn't have NVMe support. The M/B doesn't have any SATA3 headers, they are all SATA2 (this is the reason for the PCIe SATA3 adapter). The SATA adapter has native support in Linux, no additional drivers are necessary. I know this from here:

http://www.highpoint-tech.com/USA_new/series_r600-download.htm

I will plug the SSD into the mptherboard SATA2 ports.

Is there an SATA3 expansion card that you can rtecommend for use with SanDisk SSDs for optimum performance?

[shmerl]

allistar: I'm also Linux user and interested how you can see from that list that TRIM is enabled? Is it something that's enabled by default or you need to adjust drive parameters?

[allistar]

To get TRIM working I did this

- make sure the BIOS is using AHCI and not IDE for the disks. You can tell it is by:

dmesg | grep AHCI

- use the Ext4 file system. This supports TRIM.

To see if trim is supported on the drive do this:

hdparm -I /dev/sde

(where /dev/sde is the drive).

That should say "Data Set Management TRIM supported" somewhere.

- make sure you add "discard" to the options for the mount points in /etc/fstab

[shmerl]

Yep, I see it, thanks. I'm using XFS, it also supports TRIM.

About discard - after some extensive reading which I did today after getting my Extreme Pro 480GB, I figured out it's actually not a good idea, because Linux kernel doesn't implement it efficiently (and it was never fixed as far as I know).

The kernel implementation of realtime trim in 11.2, 11.3, and 11.4 is not optimized. The spec. calls for trim supporting a vectorized list of trim ranges, but as of kernel 3.0 trim is only invoked by the kernel with a single discard / trim range and with current mid 2011 SSDs this has proven to cause a performance degradation instead of a performance increase. There are few reasons to use the kernels realtime discard support with pre-3.1 kernels. It is not known when the kernels discard functionality will be optimized to work beneficially with current generation SSDs.

See this article.

So recommended way is to use periodic TRIM with fstrim. At least on Debian I did this:

sudo cp /usr/share/doc/util-linux/examples/fstrim.{service,timer} /etc/systemd/system
sudo systemctl enable fstrim.timer
sudo systemctl start fstrim.timer

It creates a systemd weekly timer which will call fstrim -a which does TRIM on each supported partition.

[allistar]

Thanks, that's interesting. The article was last modified in June 2013, I wonder how relevent it is today.

[shmerl]

I'll do some more research on this and will post here if I'll find anything.