HP StorageWorks Scalable File Share - Manual (Page 104)

Creating and modifying file systems 5–20
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
Similarly, if a second Smart Array 6404 adapter is present, the notation continues as
scsi-3/1
,
scsi-
3/2
,
scsi-4/1
and
scsi-4/2
.
Selecting the LUNs in the order in which they are listed results in adjacent OST services that are served firstly
by the same Smart Array 6404 adapter, and secondly by the same server. For a typical configuration where
there are two Smart Array 6404 adapters and four SFS20 arrays for each Object Storage Server (a total
of eight SFS20 arrays for each Object Storage Server pair), and assuming that there is one large LUN on
each array (the recommended configuration), the first four OST services will be served from the first server
in the server pair and the second four OST services from the second server, and so on for further server pairs.
In configurations where the speed of the interconnect does not exceed the capabilities of the storage
configured (for example, if a Gigabit Ethernet interconnect is used and there are two or more SFS20 arrays
per server), consider ordering the OST services in a way that supports the possibility of increasing
bandwidth by adding Object Storage Servers. This allows you to achieve better performance for jobs that
do not stripe across every available OST. For example, you could create an OST sequence where the
adjacent OST services are configured on arrays connected to port A1 of server 1, port A2 of server 2, port
A1 of server 3 and so on, across all servers; followed by arrays connected to port B1 of server 1, port B2
of server 2, port B1 of server 3, and so on.
Where the interconnect performance exceeds the storage bandwidth, using the default striping leads to
more understandable performance. Note too that if you add, for example, a pair of Object Storage Servers
to the system, and add the associated OST services to a file system, the OST services are always added at
the end of the logical list of OST services in the file system. This means that if you create a striping pattern
following the order in which the LUNs are listed by the
create filesystem
command, the striping will
be consistent with the added storage.
HP recommends that you always prefer the storage configured on SFS20 arrays connected to ports A1 and
A2 on a Smart Array 6404 adapter to different servers, and similarly for ports B1 and B2.
5.2.2.2 Creating mirrored OST LUNs on SFS20 arrays
A Smart Array 6404 adapter has four ports: A1, A2, B1, and B2. Each SFS20 array is connected to the
same port of the Smart Array 6404 adapters on each of the two servers in a server pair.
In the output from the SFS CLI commands, port A1 is referred to as
scsi-1/1
and port A2 as
scsi-1/2
;
port B1 is referred to as
scsi-2/1
and port B2 as
scsi-2/2
. Similarly, if a second Smart Array 6404
adapter is present on the server, the notation continues as
scsi-3/1
,
scsi-3/2
,
scsi-4/1
and
scsi-4/2
.
Where two Smart Array 6404 adapters are present on each server, HP recommends that each of the
component LUNs in a mirrored OST LUN is served through a different adapter. This provides optimal
resilience for the mirrored LUN. To achieve this, make sure that two arrays do not have the same or
numerically neighboring HBA/port numbers (as shown by the
sfsmgr show array
command).
When there is only one Smart Array 6404 adapter on a server, pair a LUN connected to the
scsi-1/1
port with a LUN connected to the
scsi-2/1
port when you are creating a mirrored OST LUN.