We have a Rackable Systems server used for backup storage. Recently we purchased a couple 3TB drives to expand the storage, but they are only showing a capacity of 746.52 GB as reported by 3ware's tw_cli utility and the 3ware card's BIOS. I have been searching, but I cannot find a spec sheet that lists the card's maximum single drive capacity supported. I also cannot figure out why the drive shows 746.52 GB instead of 2 TB, if in fact the 2TB compatibility barrier has been reached.

Storage controller: 3ware 9500S-4LP (Firmware: FE9X
Two new drives: Seagate SV35 ST3000VX000 3TB drives.

Are the new drives too large?
Why do the 3TB drives report smaller than the 1TB drive (listed as 931.51 GB)?

Output from tw_cli:

/c1 show

Unit  UnitType  Status         %RCmpl  %V/I/M  Stripe  Size(GB)  Cache  AVrfy
u0    SINGLE    OK             -       -       -       372.519   OFF    OFF
u1    SINGLE    OK             -       -       -       931.312   OFF    OFF
u2    RAID-1    OK             -       -       -       745.048   ON     OFF

Port   Status           Unit   Size        Blocks        Serial
p0     OK               u0     372.61 GB   781422768     *snip*
p1     OK               u1     931.51 GB   1953525168    *snip*
p2     OK               u2     746.52 GB   1565565872    *snip*
p3     OK               u2     746.52 GB   1565565872    *snip*

Edit: Added 3ware card firmware version.

  • 2
    It is quite common for 3TB drives to show up as 750GB on a controller which does not support drives greater than 2.19TiB. (Probably because 3 marketing terabyte minus 2.19TiB is about 750-ish GB). It is not 2TB due to wraparound.
    – Hennes
    Sep 5, 2012 at 20:26
  • 1
    For what it's worth, my 3ware 9550SX(U)-12 (firmware version FE9X has exactly the same limitation. I tested this with 3TB Hitachi Deskstar 7K3000 HDS723030ALA640 drive.
    – user170490
    Apr 20, 2013 at 20:44

3 Answers 3


As @Hennes said, the 745 GB reported for the 3TB drives is due to the 2.19TB limit imposed by controllers (and apparently this one) that cannot support larger drives. The fault lies in the 32-bit precision offered by LBA32.

Another resource I found here explains the limit is caused by 32-bit LBA. Someone there also reports that 3ware customer service said the 12-port version of this card will not support drives larger than 2TB, so I'm sure mine won't either.

The new 2TB drives we recently ordered are working perfectly, so we'll send the 3TB drives back.

  • 1
    Be sure to mark your own answer as accepted! This helps the backend to know this question is resolved even if you answered it yourself. Sep 11, 2012 at 19:36

There is an firmware update for the 9650SE controller v4.10.00.027 from Dec 3, 2012.

There support for up to 4TB disc's is implemented.

I use 3TB disc's with Ubuntu 14.04 server. You have to create a GPT partition table, otherwise you only see 2TB.

Use the programm parted to do this: [http://www.thegeekstuff.com/2012/08/2tb-gtp-parted/]


A relevant section from the manual:

Support for Over 2 Terabytes

Windows XP (32-bit), Windows 2003 (32-bit and 64-bit without SP1) and Linux 2.4 do not currently recognize unit capacity in excess of 2 TB. If the combined capacity of the drives to be connected to a unit exceeds 2 Terabytes (TB), you can enable auto-carving when you configure your units. Auto-carving divides the available unit capacity into multiple chunks of 2 TB or smaller that can be addressed by the operating systems as separate volumes. The carve size is adjustable from 1024 GB to 2048 GB (default) prior to unit creation.

If a unit over 2 TB was created prior to enabling the auto-carve option, its capacity visible to the operating system will still be 2TB; no additional capacity will be registered. To change this, the unit has to be recreated. For more information, see “Using Auto-Carving for Multi LUN Support” on page 78.

You may also want to refer to Knowledgease article # 13431, at http://www.3ware.com/kb/article.aspx?id=13431.

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