Export thread

  • Be sure to checkout “Tips & Tricks”
    Dear Guest Visitor → Once you register and log-in:

    This forum does not automatically send notices of new content. So if, for example, you would like to be notified by mail when Steve posts an update to his blog (or of any other specific activity anywhere else), you need to tell the system what to “Watch” for you. Please checkout the “Tips & Tricks” page for details about that... and other tips!

    /Steve.

Drive size is not rounded up

#1

D

Dagannoth

I have a couple of strange little SSDs whose labels show 16 GB, but actually fall a little short. One of them is 15,837,691,904 bytes [15.8 GB], and the other is 15,934,586,880 bytes [15.9 GB]. ReadSpeed and SR-R02 both show this as 15 GB instead of rounding up to 16. This is a tiny cosmetic issue, so no hard feelings if it doesn't get fixed. Just wanted to share this little quirk :)

ReadSpeed log:
Code: 
  +--------------------------------------------------------------------------+
  | ReadSpeed: Hyper-accurate mass storage read-performance benchmark. rel 1 |
  |  Benchmarked values are in megabytes read per second at five locations.  |
  +--------------------------------------------------------------------------+

   NOTE: This system contains an NVMe controller which is not yet supported.
         The addition of full NVMe support =IS= on our development roadmap.

Driv Size  Drive Identity     Location:    0      25%     50%     75%     100
---- ----- ---------------------------- ------- ------- ------- ------- -------
81   15GB Virtium - StorFly VSFA25C      92.8    89.2    88.3    87.1    91.9

                  Benchmarked: Tuesday, 2021-03-09 at 04:50
-----------------------------------------------------------------------------
   See the ReadSpeed forums at forums.grc.com for help and community support.

SR-R02:
SR-R0201.png


smartctl:
Code: 
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.5.4-pmagic64] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Device Model:     Virtium - StorFly VSFA25CC016G-200
Serial Number:    P1T05003893304120603
Firmware Version: 0812-000
User Capacity:    15,934,586,880 bytes [15.9 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 (minor revision not indicated)
Local Time is:    Sun Feb 28 02:48:42 2021 MST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled


#2

M

Mervyn Haynes

Actually if you divide the bytes by 1024 you get 15.47 & 15.56! Not sure if this helps though.


#3

D

Dagannoth

Drive manufacturers use 1 KB = 1,000 bytes. Here's what my 128 GB Samsung PM830 shows:

ReadSpeed:
Code: 
  +--------------------------------------------------------------------------+
  | ReadSpeed: Hyper-accurate mass storage read-performance benchmark. rel 1 |
  |  Benchmarked values are in megabytes read per second at five locations.  |
  +--------------------------------------------------------------------------+

Driv Size  Drive Identity     Location:    0      25%     50%     75%     100
---- ----- ---------------------------- ------- ------- ------- ------- -------
 82  128GB SAMSUNG SSD PM830 2.5" 7m     476.3   481.0   480.9   481.0   448.7

                  Benchmarked: Tuesday, 2017-05-16 at 17:45
 -----------------------------------------------------------------------------
   See the ReadSpeed forums at forums.grc.com for help and community support.

smartctl:
Code: 
smartctl 7.1 2019-12-30 r5022 [x86_64-linux-5.5.4-pmagic64] (local build)
Copyright (C) 2002-19, Bruce Allen, Christian Franke, www.smartmontools.org

=== START OF INFORMATION SECTION ===
Model Family:     Samsung based SSDs
Device Model:     SAMSUNG SSD PM830 2.5" 7mm 128GB
Serial Number:    S0TYNSBCB03775
LU WWN Device Id: 5 002538 043584d30
Firmware Version: CXM03D1Q
User Capacity:    128,035,676,160 bytes [128 GB]
Sector Size:      512 bytes logical/physical
Rotation Rate:    Solid State Device
Device is:        In smartctl database [for details use: -P show]
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 Feb 13 20:33:38 2021 MST
SMART support is: Available - device has SMART capability.
SMART support is: Enabled


#4

P

PHolder

Dagannoth said:
both show this as 15 GB instead of rounding up to 16.
Click to expand...
Perhaps @Steve doesn't round them at all, but simply truncates to a whole number? If that's what he did I would suspect it would be because it would be common for most drives to have more bytes than rated, not less? Such as your 128G being 128.04.


#5

Steve

Steve

Huh. Good find, @Dagannoth. Thanks!! Normally I do and would round... but I just checked, and I think the reason I didn't was that I was performing a double-length 64-bit division by 1000 (not 1024). And it didn't occur to me to check for a remainder for rounding. I'll definitely want to do that! Thanks!!


Top Bottom