Thread: 2.5Tb external not seen under Linux

hello, have looked on google , in forums seems nobody had problem yet!
m running ubuntu 11.04 newest kernel update (...38-11( today) (i know there 39-1 think still experimental) dual boot win 7 x64! on msi gx720
problem bit weird! bough new sata 300hd 2,5tb external usb2,0 controller unfortunately runs on low lba (i couldn t formated under windows 7 x64 on usb) went friend , connected win7 desk-pc on sata pci controller , got formated gpt drive (coz on 2 tb , mbr allow 2 tb) unplugged , can under windows 7 use external on usb controller coz data transfer , formation shown after first formating! under linux external still not mounted , under disk utility shown 300gb hd. problem occours due low lba of usb controller ( problem before first formating under win7 , linux)
thing don t understand why win7 able see fomatted drive , acces while linux can t see full size nor mount it!
idea 2,5tb external gpt hd running on linux 11.04?

your description bit hard follow, think you're saying following:

• you bought 2.5 tb hard disk.
• you put in external usb enclosure.
• you tried partition under windows 7 , failed.
• you removed disk usb enclosure, connected ata port on computer, , partitioned under windows 7.
• you put disk usb enclosure.
• you can use disk under windows not under linux, sees disk 300 gb in size.

if so, suspicion usb enclosure has 32-bit limit on sector addresses. given 512-byte sector size, works out 2 tib (2 x 2^40 byte, or 2200 gb) limit. given 2.5 tb (2500 gb) disk, makes difference of 300 gb, size of disk you're seeing reported. 1 possible result of going on such limit -- system reaches limit , starts counting again 0, driving car more miles odometer designed measure.

if i'm right, chances disk's working in windows dangerous half-truth; windows may reading start of partition table , filesystem data structures, , giving access first 2 tib of disk, not final ~300 gb of disk. sooner or later, it'll want store data there, result in data being written elsewhere on disk, possibly overwriting other data or filesystem data structures. nasty fix, , may lose data irrevocably.

advice shop new usb enclosure, sure 1 supports disks on 2 tib in size. alternatively, use esata enclosure, if computer supports esata. before buy new enclosure, though, might want try test hypothesis what's happened talking manufacturer of current enclosure or running tools return information on size of disk. linux partitioning tools, such parted, gparted, , gdisk, provide such information. if report disk size ~300 gb (or 2 tib), supports hypothesis. can check in windows, too, i'm less familiar windows tools (except gdisk, available both linux , windows).

1 final note: units can confusing when describing disk sizes. technically, si units (kb, mb, gb, tb, etc.) refer power-of-10 values (10^3, 10^6, 10^9 10^12, etc.), whereas [ur=http://en.wikipedia.org/wiki/ieee_1541-2002]ieee-1541[/url] units (kib, mib, gib, tib, etc.) refer power-of-2 values (2^10, 2^20, 2^30, 2^40, etc.). also, "b" means "bit" whereas "b" means "byte" (8 bits). disk manufacturers use si units measure disk sizes, ieee-1541 units more natural fit many computer measurements. 32-bit disk size limit of 2 tib example, why 2.5 tb disk has 300 gb above 2 tib mark -- 2.5 tb 2.27 tib, , 0.27 tib 0.30 tb, or 300 gb.

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