HP StorageWorks 9100 Extreme Data Storage System administration guide V1.0.2 (AN540-96018, February 2010)

7 Managing data

Creating a filesystem

The exdsmgr create filesystem command creates PSFS filesystems. The create filesystem

command works as follows to create a filesystem:

• If not otherwise specified, the exdsmgr create filesystem command will create two

filesytems, each using 4 LUNs. Each resulting filesystem uses 29 TB of space.

• When you specify a filesystem size, the command matches the requested filesystem size against

the available (free/unused) LUNs. For a filesystem of 7.25 TB, it picks one LUN; for 14.51 TB it

picks two LUNs, and so on, up to the maximum of 58 TB and eight LUNs. See Filesystem sizes for

a list of the suitable sizes. When matching filesystem size and LUN size, the create filesystem

command allows 10 percent mismatch. For example, if you entered 7.9 TB or 6.6 TB, they would

match a 7.25 TB LUN. In addition, since whole LUNs are used to construct the filesystem, the ac-

tual space used for the filesystem might be different than the value you entered (for example, if

you enter 6.6 TB, the filesystem actually uses 7.25 TB of space).

• The command examines the specified array.

• The command matches the requested filesystem size against the available (free/unused) LUNs.

For a filesystem of 8 TB, it picks one LUN, for 16 TB it picks two LUNs, and so on, up to the

maximum of 64 TB and eight LUNs.

• A dynamic volume (psv) is created using these LUNs.

• A filesystem is formatted on the psv. The block size depends on the filesystem size as follows:

• Filesystem size: 0-16 TB block size: 4 K

• Filesystem size: 16-32 TB block size: 8 K

• Filesystem size: 32-64 TB block size: 16 K

• The filesystem is mounted on all servers.

Filesystem sizes shows the filesystem sizes that result from using different numbers of LUNs:

Table 5 Filesystem sizes

Filesystem size based on LUN size of 7427 GBNumber of LUNs used

7.25 TB1

14.51 TB2

21.79 TB3

29 TB4

36.26 TB5

43.52 TB6

50.77 TB7

9100 Extreme Data Storage System administration guide 59