Does heads count different make drives difference?

Posted on 2012-09-05
Last Modified: 2012-09-05
Hi there,

I am using two Seagate drives ST31500341AS to create RAID 1 system in a NAS system.

However NAS reported that two drives are not identical. From the fdisk -l I got following info. - heads count and sector count are different.

Disk /dev/sdb: 1500.3 GB, 1500301910016 bytes
255 heads, 63 sectors/track, 182401 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/sda: 1500.3 GB, 1500301910016 bytes
256 heads, 63 sectors/track, 181688 cylinders
Units = cylinders of 16128 * 512 = 8257536 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

My question is why does the drives with same model and same firmware come with different specs, and are they really different?

Is there anything I can do to make them identical?
Question by:tomcattyy
    LVL 13

    Accepted Solution

    That may be a difference in the way the partitions were created, so if you delete all the partitions and start over using the same method for both drives, they may very well be seen as identical again.
    LVL 46

    Assisted Solution

    The number of heads reported by the O/S is virtualized/emulated. They mean nothing. Ignore the values.

    It doesn't buy you anything making the count identical, but this can be done with a mode page editor.

    Ignore the issue. It is of no consequence.
    LVL 1

    Author Comment

    I end up place both disks into a PC and format as NTFS to eliminate the original partition and get the RAID 1 system get going.

    Thanks for all the info.
    LVL 13

    Expert Comment

    by:Norm Dickinson
    We are here to help!

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    How to run any project with ease

    Manage projects of all sizes how you want. Great for personal to-do lists, project milestones, team priorities and launch plans.
    - Combine task lists, docs, spreadsheets, and chat in one
    - View and edit from mobile/offline
    - Cut down on emails

    As you can read I recycle all my old hardware and the time has come that my power supply of 200 Watt cannot provide enough power for my backup server. I have lots of Compaq power supply's laying around, so I figured to use one of these PSU's. I t…
    No matter the version of Windows you are using, you may have some problems with Windows Search running too slow or possibly not running at all. Before jumping into how you can solve this issue, just know there are many other viable alternative deskt…
    Migrating to Microsoft Office 365 is becoming increasingly popular for organizations both large and small. If you have made the leap to Microsoft’s cloud platform, you know that you will need to create a corporate email signature for your Office 365…
    In this sixth video of the Xpdf series, we discuss and demonstrate the PDFtoPNG utility, which converts a multi-page PDF file to separate color, grayscale, or monochrome PNG files, creating one PNG file for each page in the PDF. It does this via a c…

    737 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    22 Experts available now in Live!

    Get 1:1 Help Now