Ddrescue RAID

Hi All;
I am new to Linux and Ubuntu. I am setting up a RAID for a media server and want to be sure I do it right and in the proper order.

Based upon feedback received on this forum I think it makes most sense to partition my 4 TB disks into 2 partitions of 2 TB each.

So am I correct in running MDADM FIRST on both (Unpartitioned) 4 TB disks to create RAID 1 and then partition (Using Parted) the resulting single 4 TB disk that I create with MDADM into two 2 TB partitions? Thanks.

Tim

My attempts to back-up to an external hard disk finally met with apparent success but I cannot now mount the target drive.

To summarize:-
1. Installing a SATA hard disk, identical to my computer's main drive, in a USB 2.0 caddy and attaching this to the computer resulted in qualified recognition. 'fdisk' 'saw' both the main drive, as sda, and the USB drive, as sdb, respectively but initially noted that the latter, “... doesn't contain a valid partition table.” This was hardly surprising. At the point of first connection the external drive was essentially a 'bare metal' device, having had its data wiped. Nevertheless, 'fdisk' correctly reported its size, number of heads and cylinders, etc.
2. 'dmesg' also correctly identified the external disk as sdb, reporting its type and the USB port to which it is connected.
3. 'df' ignores the second hard drive, reporting only the main disk.
4. Attempts to clone/back-up the main disk to the external disk using the recommended tools EaseUS Todo back-up and RedoBackup, booting respectively from appropriate USB memory sticks, both failed. Neither utility was prepared to write to the external disk. EaseUS acknowledged the latter but crashed the whole computer when instructed to perform the clone. RedoBackup failed to recognize the external disk.
5. Then came the break-through. A bit more Net browsing led me to try the command 'dd if=/dev/sda of=/dev/sdb'. The main disk was bit-copied (cloned) to the external disk at roughly 20Gb per hour, meaning that my 80Gb disk was copied in just under 4 hours. Checking 'dd's resulting report showed what appeared to be a perfect copy.

So far, so good. I now have a back-up which, being identical to the main disk, should, I assume, be bootable. In the event of trouble with the main disk I should be able simply to exchange it for the external disk and carry on from the point at which I made my last back-up. I cannot, however, access and read the external disk. I assume that it must have a partition table and be mounted. The first requirement appears to have been resolved by the cloning operation. 'fdisk' reports no trouble with the partition table on the cloned external disk. It lists /dev/sb1 as the bootable Linux partition, /dev/sdb2 as the Extended partition and /dev/sdb5 as the Linux swap / Solaris partition, exactly mirroring the corresponding entries for the main, sda, drive.

My attempts to mount the external disk have all failed, however. I clearly do not understand the syntax of the mount command or have failed to meet some other requirement. 'mount' objected without hesitation to my early mistakes but “mount -t dev/sdb” was instantly accepted. No error messages or other output resulted and the command prompt was immediately redisplayed but 'mount' then failed to show that the external drive had been mounted. If I try something like 'mount -t /dev/sdb1 /mnt/xdisk', where xdisk is a directory I have been told to create, then I am presented with a prolix description of 'mount's syntax, most of which leaves me bewildered. 'mount' then once again confirms that sdb1 does not feature in the list of mounted devices.

Can someone offer any suggestions? I have read one or two of the other posts on this topic but none of the details match my problem too well and I did not understand some of the replies. If I try to add a line to /etc/fstab, for example, I find that I do not have a directory called 'fstab', only 'fstab.d' and that is empty.

I have roughly one year's experience with Linux Mint 13 which I chose because it so closely resembled Windows XP.

Hello All;
I was able to create a RAID array mode 1 using two 4TB drives but the resulting array (md0) is listed as "4.0 TB Unknown" in the Disks gui.

I am wondering if this is correct to leave it as-is or if I have to set this to a partition type (ext4?)for it to work properly?

Thanks.

Tim

Good evening;
Following instructions on-line I attempted to create a bootable USB drive (32GB Sandsik extreme) with Linux 17.1 installed to enable a trial before attempting a permanent install beside windows 7 on a new computer with Win7 prof. installed.

On the usb I see a 4.0 GB area highlighted in G Parted but not accessible from the Linux file manager. This shows up as a ~1.4 GB sub-directory titled casper. and also as 4.0 GB 'file' named casper-rw. Can anyone explain what is the purpose of this sub-directory? The software I used to create the usb bootable drive and install Linux to is 'Universal-USB-Installer-1.9.5.9'. This is a windows executable. My intent was to create a bootable usb drive for Linux that also contained my required hardware drivers, etc. This doesn't appear to be working 100%; although Linux 17.1 boots the nvidia hardware drivers do not appear to be available even though I downloaded these and they are on the same usb. On boot-up a message box indicates that hardware acceleration is not enabled and higher than normal processor usage may occur.

Any assistance / direction, etc. would be greatly appreciated.

Regards;
Mike

Hello all

I am trying to create a Hyper-V 2012 Virtual machine running Cent0S 6.5 for a client. Currently I have the VM set up with two SCSI disks one of size 25GB and one of size 60 GB.. The 25 GB disk will be the OS disk and the 60 GB disk will be the data disk which holds the data from the database. I want to create an LVM on the 60 GB disk and increase it over time as the database gets bigger. As soon as the disk gets to about 1 TB, I will create a third disk, and extend the Volume Group to include that third disk as well. The third disk will eventually grow past 1TB as well (but not 2TB)

Overall my question is, would this type of set up be possibly using a MBR Bios set up? or would I HAVE To use GPT?

all help is greatly appreciated!

I had Kali and Linux Mint installed and erased Mint to install Centos7. Grub was totally deleted and I could only boot into grub recovery. Many hours of cussing later I got Kali back, I can see Centos filesystem mounted on my desktop and in disk utility. I never finished setting Centos up as I was rushed out the door which probably caused the problem in the first place, for some reason it's raid and although it's 2 harddrives they are not set up for raid and 1 is Kali and 1 is Centos. The Centos boot folder is still empty after running grub-install on it twice and it does not show in grub. How do I get Centos as an option?

Hello, I am wanting to eventually migrate from software RAID to hardware.
I remember one time I attempted to migrate a system with software RAID to a non-RAID system but of course it crashed because it was expecting RAID at the new location.
I need to be able to copy an entire filesystem from a software-RAID system without this being an issue, so mainly I need to know which files/folders to skip.
Thanks in advance.

Hi, all, I am new to the forum and quite new to Linux, I am running Mint and Kali from a USB drive, all is going well with with the software and I am starting to find my way around it.

So, now to my question, I have 15 machines which all run from a CF card and the card has multiple partitions and is a Windows Embedded XP, not that the operating system makes any difference, I need to upgrade all the CF cards from 2gb to 4gb, so unfortunately Windows isn't an option to use to copy the drives as it doesn't recognise multiple partitions on a removable drive, so I cant just remove the drive, clone it and fit the new one.

What I need is a method of cloning the drive completely with both partitions, I have read about dd but cant seem to see anything about doing this with multiple partitions, as Linux sees it as two drives when I plug it in, how can I use dd or anything else to clone the drive which is bootable and has two partitions?

At some point I would like to automate the process as I could have many of these machines/drives to upgrade, is there a way to write a program that will automatically back up the drives from a USB drive and then reinstall it, I have seen this done before but I am not sure if this method did the whole drive, just the main drive or all partitions?

I have Linux enterprise server 11 sp3 with 3 250 GB WD blue drives in a raid 5 configuration.

Server “A” (external drive not plugged in):
Code:

Disk /dev/sda: 499.0 GB, 499021512704 bytes
255 heads, 63 sectors/track, 60669 cylinders, total 974651392 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00059fd2

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *        2048     1028095      513024   83  Linux
/dev/sda2         1028096    21993471    10482688   82  Linux swap / Solaris
/dev/sda3        21993472   974651391   476328960   8e  Linux LVM

Disk /dev/mapper/VG_SYSTEM-ROOT: 487.8 GB, 487755612160 bytes
255 heads, 63 sectors/track, 59299 cylinders, total 952647680 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00000000

Disk /dev/mapper/VG_SYSTEM-ROOT doesn't contain a valid partition table

I am trying to clone this machine to another server, both servers are Dell Poweredge 1900, with 3 – 250 WD drives (the only difference is the ‘B’ server has WD Cavier drives), pretty much identical machines, same processor and ram. I have a 2TB ext hard drive that I am using to store the output of DD. I have booted from the CD to a rescue system, then mounted my 2TB ext and did the following:
Code:

    # dd if=/dev/sda conv=sync,noerror bs=64k | gzip –c | split –a3 –b 2G –verbose - /mnt/exthd/

This gives me the following files on my external hard drive:
Code:

    
-rwxr-xr-x 1 root root 2147483648 Jan 10 21:00 aaa
-rwxr-xr-x 1 root root 2147483648 Jan 10 21:31 aab
-rwxr-xr-x 1 root root 2147483648 Jan 10 21:53 aac
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:05 aad
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:10 aae
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:17 aaf
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:24 aag
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:31 aah
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:37 aai
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:43 aaj
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:50 aak
-rwxr-xr-x 1 root root 2147483648 Jan 10 22:56 aal
-rwxr-xr-x 1 root root 2147483648 Jan 10 23:02 aam
-rwxr-xr-x 1 root root 2147483648 Jan 10 23:06 aan
-rwxr-xr-x 1 root root 2147483648 Jan 10 23:12 aao
-rwxr-xr-x 1 root root 2147483648 Jan 10 23:32 aap
-rwxr-xr-x 1 root root  324998512 Jan 10 23:35 aaq

Now, I boot to the rescue system on server ‘B’ with the external drive plugged in, and run fdisk:
Code:

Disk /dev/sda: 498.8 GB, 498753077248 bytes
255 heads, 63 sectors/track, 60636 cylinders, total 974127104 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00059fd2

   Device Boot      Start         End      Blocks   Id  System

Disk /dev/sdb: 2000.4 GB, 2000398933504 bytes
255 heads, 63 sectors/track, 243201 cylinders, total 3907029167 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00015a3d

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048  3907028991  1953513472    c  W95 FAT32 (LBA)

Notice sda is only 498.8GB where on server ’A’, it was 499.0. when I try to restore my files from the DD, I get an out of space error. To restore, I use the following:
Code:

    # cat /mnt/exthd/aa* | gunzip –c | dd of=/dev/sda
    
dd: writing to ‘/dev/sda’:  No space left on device
974127105+0 records in
974127104+0 records out
498753077248 bytes (499 GB) copied, 37067.3 s, 13.5MB/s

My guess, is that although the drives are the same capacity (3 – 250GB in RAID 5 array), the number of cylinders is different because it is a different model, and that is where it is running out of space, although I wouldn’t think it would.

Please correct me if I am wrong as I am a newbie, but if I do “# dd if=/dev/sda” that will take all the partitions with it? Such as sda1, sda2, sda3 correct?

Hi All

Please could someone assist me with a software raid 5 array issue i am having?

About a week or so ago i was asked to have a look at a mate of mine's Company Server that had crashed after a power failure - no ups and close to 9GB data with no backup.
HP Proliant mini server running OpenMediaVault v1.9. with a software raid5 setup consisting of 4x 3TB Western Digital Hard drives


The 80GB boot drive crashed (hardware malfunction) so i replaced it and installed the server with OpenMediaVault 1.9 as was previously installed. When starting up however i noticed that none of the shares were available and upon closer inspection discovered that the raid to had crashed. I therefore re-assembled the raid but now have no file system nor any partitions on any of the 4x drives.

This is about the extent of my knowledge base when it comes to Linux, and again i don't know that i'd want to risk it with no backup of the data.

I have run fsck /dev/md1, but this reports an error 2 while executing fsck.linux_raid_member not found.
Please i am desperate for some advise!

Thanks
Wayne