HPUX striping strip

Comparison of the two striping Methods

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1. The traditional method is to use the-I/-I parameter of lvcreate. Specific Commands include:# Lvcreate-R n-I 4-I 64-N lvdata-l 1000/dev/vgdata
In this way, an LV named lvdata is generated, and the size is 1000 MB. Every 64 K of data is jumped to the next hard disk, with four hard disks as a cycle.
The size of each data block (stripe size) can be from 4 K to 32 MB. generally, when every Io of the system is very small, a small stripe size can be selected. The principle is that the size of stripe cannot be smaller than that of a single Io. In actual use, I found that different stripe Size usually has little impact.
The advantage of this method is that it is easy to use, but it also has obvious shortcomings. After this method is used for striping, if you need to expand the LV, in the above case, you need to have four hard disks with enough space. For example, if the lvdata capacity is expanded to 2000 MB, the remaining space on each hard disk is MB. This may not be a problem. However, I have met HP engineers who have set up LV, and the agent has created some new LV on its own, without using the Strip parameters, just to use up the space of a hard disk. In this way, although there is still much space for the other three hard disks, the LV cannot be expanded. At last, we can only back up the LV data that is added after the downtime and recreate it. Even if the LV is created in a strip mode, when the space of these hard disks is used up and the hard disk needs to be added, the increased hard disk must be a multiple of the stripes. In the above example, it is a multiple of 4 to ensure that the original LV can be expanded.2. Another method is extend based striping.Unlike the-I/-I method, this strip is based on PE. That is, after each PE is written, the data jumps to the next hard disk. Generally, the PE size is 4 MB. This method is a little effort in the configuration process and requires editing the/etc/lvmpvg file. When LV is created, data is distributed across all PVS listed in lvmpvg. When the space is used up and more than two hard disks are added, data can be evenly distributed on the newly added hard disks.
If you can only add one PV, then the extend base striping attribute (lvchange-d n) of a disable LV can still be expanded.
Extend based striping supports tracing, but traditional-I/-I does not. It is helpful to support tracing in some data migration scenarios. The method for configuring extend based striping is as follows: 1. Select the appropriate device (that is, the Controller and IO port used to Access XP, VA, and other devices)
2. Edit the/etc/lvmpvg file and create a PVG for the corresponding VG.
# Vi/etc/lvmpvg
VG/dev/vgdata
PVG pvganyname
/Dev/DSK/c8t0d0
/Dev/DSK/c10t0d1
/Dev/DSK/c8t0d2
/Dev/DSK/c10t0d3
3. Generate LV
# Lvcreate-d y-s g-r n-l 1000-N lvdata/dev/vgdata