CSS Corp Open Source Services

UEC: Attach EBS volume to a running instance

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Linux Instances

First create a volume of the required size using euca-create-volume

$ euca-create-volume -s 10 -z mycloud
VOLUME  vol-333C04B8    10       creating        2010-03-26T05:20:56.383Z

Check the available volumes and their status with euca-describe-volumes

$ euca-describe-volumes
VOLUME  vol-333C04B8    10   mycloud   available     2010-03-26T05:20:56.383Z

Now attach the volume to a running instance using euca-attach-volume

$ euca-attach-volume -i i-41620887 -d /dev/sdb vol-333C04B8

The volumes status changes from “available” to “in-use” if it is attached properly.

$ euca-describe-volumes
VOLUME  vol-333C04B8    10  mycloud in-use  2010-03-26T05:41:28.019Z
ATTACHMENT      vol-331F04B2    i-41620887      unknown,requested:/dev/sdb  2010-03-26T05:43:51.343Z

Once you login to the instance through ssh, you should see the new volume.

$ sudo fdisk -l

Disk /dev/sda: 2195 MB, 2195718144 bytes
4 heads, 32 sectors/track, 33504 cylinders
Units = cylinders of 128 * 512 = 65536 bytes
Disk identifier: 0x000adc1c

 Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1       32769     2097152+  83  Linux
/dev/sda3           32769       33504       47071   82  Linux swap / Solaris

Disk /dev/sdb: 10.7 GB, 10737418240 bytes
64 heads, 32 sectors/track, 10240 cylinders
Units = cylinders of 2048 * 512 = 1048576 bytes
Disk identifier: 0x00000000

Disk /dev/sdb doesn't contain a valid partition table

Now /dev/sdb is ready to be formatted and mounted so that it can be used as a permanent storage. Unmount the volume before bringing down the instance, to avoid any data corruption.

Windows Instances

For windows instances, creating the volume and attaching the volume would be the same.

NOTE: Even while attaching the device need to specified as /dev/sdb

The only change is the way this disk is accessed. Once the disk is attached to a running windows instance, perform the following steps:

  • Connect to windows instance via RDP
  • Go to Start -> Run and type diskmgmt.msc without the quotes. Select OK. This opens the Disk Management console.
  • Right click on the new disk at the bottom of the list and choose Initialize Disk.
  • A pop up will appear, choose OK.
  • Next right click on the volume and select New Partition.
  • A wizard appears and accept the defaults, other than change the disk letter as per need.
  • Finish up the wizard, and windows will now format the partition.

After completion the disk management tool shows a healthy partition on the new drive.

Troubleshooting

If the network configuration on CC and NC has changed, say either the interfaces changed, due to which the ip addresses have also changed. In such cases the following errors appear in nc.log

[EUCAERROR ] libvirt: operation failed: adding scsi disk failed: pci_add pci_addr=auto storage file=/dev/etherd/e0.8,if=scsi
failed to add file=/dev/etherd/e0.8,if=scsi
 (code=9)
[Fri Mar 26 10:57:39 2010][001621][EUCAERROR ] virDomainAttachDevice() failed (err=-1) XML=
[Fri Mar 26 10:57:39 2010][001621][EUCAERROR ] ERROR: doAttachVolume() failed error=1

In order to overcome this, the configuration has to be changed accordingly from the webUI. Access the webUI of UEC using https://:8443. On Configuration page, under Clusters section, replace the correct ip and interface name for Storage Controller.

See below screenshot.

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Written by kiranmurari

March 26, 2010 at 11:58 am

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