This topic discusses network server storage spaces and how to name them.
Operating systems such as Windows®, Unix and Linux® work with what they see as physical disk drives; there is little or no virtualization of storage at an operating system level. Because i5/OS™ virtualizes all disk storage, you can carve out chunks of disk space from the storage pool to form virtual disk drives, which we can then allocate to Linux and Windows. We call these virtual disk drives, storage spaces. Integrated Linux and Windows servers, as well as AIX 5L™ and Linux running in iSeries™ partitions, see these storage spaces as physical disk drives.
The i5/OS object that is used to create a Windows or Linux virtual drive is called a Network Server Storage Space (NWSSTG), or storage space for short. These storage spaces are stored in the root of the i5/OS Integrated File System (IFS) in a directory called /QFPNWSSTG. You can use the Work with Links (WRKLNK) command from an i5/OS command line to view the contents of the /QFPNWSSTG directory. This same storage space architecture is used not only by integrated Linux servers, but also by integrated Windows servers, and Linux and AIX 5L running in iSeries logical partitions. Storage spaces can be interchanged between each of these different operating systems.
The amount of disk storage that you create for your servers is taken directly from the iSeries available storage, and each Windows or Linux virtual drive is physically scattered across all the real disk drives in the iSeries disk pool.
Storage spaces are different from other i5/OS file objects because the size that you specify for a storage space is completely allocated at the time it is created. This is because integrated Linux and Windows servers need to be able to connect to and format a drive of a fixed size.
The Linux server install command (INSLNXSVR) creates only two drives. These drives are used to store the Linux operating system (called the system drive) and some IBM-supplied drivers (called the installation drive).
It is a good idea to make a backup of the system drive before and after you make changes to the operating system. If something should happen, you can recover by restoring a backup of the system drive, rather than rebuilding the server from scratch. In order to recovery quickly from a system failure, you should not store user files on the system or installation drives. Files and data that change frequently should be stored on a different drive.
Before you start creating new drives for your server, take some time to calculate what the server needs now and in the future. After the server has been installed you can create additional drives for your Linux server at any time. These drives can be linked to the server while it is shut down (static linking) or started (dynamic linking). This means that you do not need to allocate large portions of your iSeries storage when the server is created; you can create additional drives of any size you wish (up to the limit) when they are needed.
Here is a summary of the operations that you can perform on Linux drives:
Linux disk drive operations can be performed in two ways:
It is important to decide on a naming convention for your storage spaces; otherwise you might have trouble correlating storage space names that you see from the i5/OS side with drives that you see from the Linux side. This can be especially difficult if you have both statically linked and dynamically linked drives.
When the Linux server is created, two drives are created by default: The system and installation drives. They pick up the name of the NWSD with a 1 appended for the system drive, and a 2 appended for the installation drive. For example, for an NWSD named REDHAT1, a system drive named REDHAT11 and an installation drive named REDHAT12 are created. It is not possible to rename these drives directly. You must copy them and then supply a new name to the copy. However, it is rarely necessary to rename these two drives, as it is obvious which NWSD they are associated with.
We do, however, recommend that you systematically name any additional drives that you create for a server. We suggest that you use the next available Linux device name for each new drive. By default, Linux allocates the SCSI device names /dev/sda and /dev/sdb to the system and installation drives, respectively. Therefore, we recommand that you name the first additional storage space you create for a server nwsd-namesdc, nwsd-namesdd, and so on. Using this naming convention for an NWSD named REDHAT1, additional storage spaces would be named REDHAT1SDC, REDHAT1SDD, and so on. Note that the maximum length of a storage space name is 10 characters.