HP StorageWorks Scalable File Share User Manual
Page 101
Creating a file System — SFS20 storage
5–17
Number of OST services
You will be asked to specify how many OST services the file system is to use. A list of all available OST LUNs
(that is, OST LUNs that are not already part of a file system) is displayed. The maximum number of OST
services that the file system can have is determined by the number of available OST LUNs. For example, if
the system has eight OST LUNs and you decide to mirror each OST service across two LUNs, you can create
four OST services. If you decide not to mirror each OST service across two LUNs, you can create up to eight
OST services. See Section 5.2.2.2 for more information on creating mirrored OST LUNs.
Note that you can only decide to mirror all OST services or none (that is, you cannot mirror some OST
services and not mirror other OST services). However, you can decide to mirror OST services even if you
have opted not to mirror the MDS service.
LUN numbers and preferred servers
You will be asked to specify a LUN number and preferred server for each OST service. (The list of available
OST LUNs will be displayed.)
To help you to balance the distribution of LUNs to servers, the
create filesystem
command shows the
default preferred server for each LUN; selecting the default preferred server will ensure that the OST serving
is optimally balanced. In the example below, LUNs 8, 11, 13 and 15 are visible to (that is, are on arrays
attached to) the
south3
and
south4
servers. This means that either of these servers could serve (that is,
be the preferred server for) any of these LUNs. However, although it is possible for the
south3
server to
serve LUNs 8, 11, 13 and 15, this is not an optimal balance because it leaves the
south4
server unused.
In this example, it would be good practice to select
south3
(the default) as the preferred server for LUNs
8 and 13 and
south4
(the default) the preferred server for LUNs 11 and 15.
Here are the available LUNs which you can assign to OSTs:
LUN Array Controller Role Size (GB) Visible to Preferred
--- ----- ---------- ---- --------- --------- ---------
8 3 scsi-1/1 ost 1050 south[3-4] south3
13 5 scsi-2/1 ost 1050 south[3-4] south3
11 4 scsi-1/2 ost 1050 south[3-4] south4
15 6 scsi-2/2 ost 1050 south[3-4] south4
17 7 scsi-1/1 ost 1050 south[5-6] south5
21 9 scsi-2/1 ost 1050 south[5-6] south5
19 8 scsi-1/2 ost 1050 south[5-6] south6
23 10 scsi-2/2 ost 1050 south[5-6] south6
Please enter the LUN you wish to use [8]: 8
Please enter the preferred server for this OST LUN [south3]: south3
For examples of file system configurations, see Appendix C.
For information on how to order OST services in the file system to support optimal performance, see
File system optimization for primary usage
You can optimize I/O operations on the OST services in a file system by specifying the file I/O pattern that
you expect on the file system. The options are:
•
Predominantly large file streamed sequential access
•
Large numbers of smaller files
Select the scenario that best suits your needs. If you choose the second option (large numbers of small files),
the
mballoc
option is added to the list of options that can be specified for OST services (this list is presented
later).