How to verify the stripe is correctly set

[ng_7]

Hi, Experts,

I have done Stripping on 2 36GB hardisk on lvol1 of vg01, can someone tell me how do i confirm that my job is successfully done.
attached herewith the vgdisplay -v and sam prinshot for your perual.

dev:/var/sam/log# vgdisplay -v vg01
--- Volume groups ---
VG Name /dev/vg01
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 1
Open LV 1
Max PV 16
Cur PV 2
Act PV 2
Max PE per PV 8683
VGDA 4
PE Size (Mbytes) 4
Total PE 17362
Alloc PE 16250
Free PE 1112
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vg01/lvol1
LV Status available/syncd
LV Size (Mbytes) 65000
Current LE 16250
Allocated PE 16250
Used PV 2


--- Physical volumes ---
PV Name /dev/dsk/c2t0d0
PV Status available
Total PE 8681
Free PE 556
Autoswitch On

PV Name /dev/dsk/c2t2d0
PV Status available
Total PE 8681
Free PE 556
Autoswitch On



thanks
regards
ng

[Aneesh Mohan · Accepted solution]

Hi,

As per the below output ,stripping is perfect.


#vgdisplay -v vg01
Total PE 17362
Alloc PE 16250
Free PE 1112

--- Logical volumes ---
LV Name /dev/vg01/lvol1
LV Status available/syncd
LV Size (Mbytes) 65000
Current LE 16250
Allocated PE 16250
Used PV 2


--- Physical volumes ---
PV Name /dev/dsk/c2t0d0
Total PE 8681
Free PE 556


PV Name /dev/dsk/c2t2d0
Total PE 8681
Free PE 556



Current LE /2 (16250/2= 8125) --- Should be Total PE - Free PE of the PE of the PV`s ) ie ,8681- 556 = 8125

Its sounds good -- :)



Aneesh

[Matti_Kurkela]

There are actually two methods of striping:
the more modern one is created with "lvcreate -i" and has a configurable stripe size.

The old method is called "extent-based striping". It places the first extent of a LV on the first PV, the second on the next PV and so on. In effect, the stripe size equals extent size... which is not optimal unless your application accesses data in blocks that are significantly larger than one extent.

Either way, one command is enough to check for both methods:

Run "lvdisplay -v /dev/vg01/lvol1 |more".
Check the "Stripes" value.
If it's not 0, the LV is properly striped.

For old-style extent-based striping on two disks, see the list of extents at the end: you should see all the odd-numbered extents on one disk and all the even-numbered extents on another.

Your screenshot in the .doc file seems to be totally irrelevant. If you did make a mistake, you could ask the moderators to remove it. See the "your questions regarding ITRC forums" section and the " issues regarding moderator intervention" thread.

MK

[ng_7]

thanks to all your information. Lastly , May i check with you guy what is the optimal stripe size. I set stripe size to 128kb for 2 36GB hard disk, I wonder if this is correct.

[A. Clay Stephenson]

As I tried to tell you before there is no one-size fits all optimum stripe size. For an LVOL which houses a vxfs filesystem, 64-128KiB generally provides good performance because vxfs filesystems always try to do i/o in large chunks. The only way to determine optimum stripe size is to measure throughput using i/o patterns which closely match your applications. The main advantage of striping is to spread the i/o across several physical devices and thus the optimum stripe size varies with the kinds of disks, the number of disks on a controller, the load, and the i/o patterns. If you want an answer then measure ---- and your answers will only be as good as the correlation between your tests and the actual application.

[ng_7]

thank you for all your information.

[ng_7]

I found the solution from all the reply. thank you so much.