samrocketman/slow_drives.md

## slow_drives.md

      
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              slow_drives.md
            
          
    reliability testing

I bought 4 SSD drives.  I'm going to open 8 terminals (2 for each drive) to infinitely write to the drives over and over again.
2 terminals writing at the same time:

1 for writing zeros to the drive
1 for writing random 1's and 0's to the drive

I'm going to let the drives write for anywhere from three to five days 24 hours a day.  If the drives are bad then they should fail within that window.
Analyzing reliability (as root user)

Install SMART tools package in ubuntu.
apt-get install smartmontools

List the drives:
fdisk -l

The above lists my 4 drives as /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd.
Analyze the SMART data of the drives.
smartctl -a /dev/sda

SMART data will tell me about a drive failure.
testing speeds

zero writing example
while true;do dd if=/dev/zero of=/dev/sda bs=1000M oflag=dsync status=progress;done

random write example
while true;do dd if=/dev/urandom of=/dev/sda bs=1000M oflag=dsync status=progress;done


sda zero: 46137344000 bytes (46 GB, 43 GiB) copied, 637.615 s, 72.4 MB/s

random: 6106906442 bytes (6.1 GB, 5.7 GiB) copied, 544.936 s, 11.2 MB/s
sdb zero: 128035676160 bytes (128 GB, 119 GiB) copied, 496.908 s, 258 MB/s

random: 23655873855 bytes (24 GB, 22 GiB) copied, 567.166 s, 41.7 MB/s
sdc zero: 128035676160 bytes (128 GB, 119 GiB) copied, 495.048 s, 259 MB/s

random: 24092081458 bytes (24 GB, 22 GiB) copied, 596.461 s, 40.4 MB/s
sdd zero: 45088768000 bytes (45 GB, 42 GiB) copied, 705.389 s, 63.9 MB/s

random: 6073352011 bytes (6.1 GB, 5.7 GiB) copied, 607.209 s, 10.0 MB/s

sda is 1/4 speed

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG MZ7PC128HAFU-000H1
Serial Number:    S0U2NSAD114738
LU WWN Device Id: 5 002538 043584d30
Firmware Version: CXM05H1Q
User Capacity:    128,035,676,160 bytes [128 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-2 T13/2015-D revision 2
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Sat Dec  2 01:00:33 2017 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

sdb

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG MZ7PC128HAFU-000H1
Serial Number:    S0U2NSAD303973
LU WWN Device Id: 5 002538 043584d30
Firmware Version: CXM05H1Q
User Capacity:    128,035,676,160 bytes [128 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-2 T13/2015-D revision 2
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Sat Dec  2 01:02:31 2017 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled

sdc

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG MZ7PC128HAFU-000L5
Serial Number:    S11VNSAD301864
Firmware Version: CXM07L1Q
User Capacity:    128,035,676,160 bytes [128 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ATA8-ACS T13/1699-D revision 4c
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Sat Dec  2 01:02:57 2017 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled


sdd is 1/4 speed

=== START OF INFORMATION SECTION ===
Device Model:     SAMSUNG MZ7PC128HAFU-000H1
Serial Number:    S0U2NSAC603416
LU WWN Device Id: 5 002538 043584d30
Firmware Version: CXM05H1Q
User Capacity:    128,035,676,160 bytes [128 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        Not in smartctl database [for details use: -P showall]
ATA Version is:   ACS-2 T13/2015-D revision 2
SATA Version is:  SATA 3.0, 6.0 Gb/s (current: 6.0 Gb/s)
Local Time is:    Sat Dec  2 01:01:48 2017 UTC
SMART support is: Available - device has SMART capability.
SMART support is: Enabled