Performance Through Disk Striping

[AntriBouzar]

Hi All;

I have done striping on 12 x 73 GB on external HPstorage boxe which is connected to the server server through two cards fiber;
So I waited that the data written would be very fast on the logical volume, unfortunately the rate of write data is very slow on the logical volume .
I give an example : for writing 632GB of data it tooks about 15 hours to finish; can you tell me what is the wrong in my configuration :


--- Volume groups ---
VG Name /dev/vg08
VG Write Access read/write
VG Status available
Max LV 255
Cur LV 1
Open LV 1
Max PV 16
Cur PV 12
Act PV 12
Max PE per PV 65000
VGDA 24
PE Size (Mbytes) 16
Total PE 52488
Alloc PE 52488
Free PE 0
Total PVG 0
Total Spare PVs 0
Total Spare PVs in use 0

--- Logical volumes ---
LV Name /dev/vg08/lvol1
VG Name /dev/vg08
LV Permission read/write
LV Status available/syncd
Mirror copies 0
Consistency Recovery MWC
Schedule striped
LV Size (Mbytes) 839808
Current LE 52488
Allocated PE 52488
Stripes 12
Stripe Size (Kbytes) 64
Bad block on
Allocation strict
IO Timeout (Seconds) default

--- Distribution of logical volume ---
PV Name LE on PV PE on PV
/dev/dsk/c18t1d0 4374 4374
/dev/dsk/c19t2d0 4374 4374
/dev/dsk/c18t3d0 4374 4374
/dev/dsk/c19t4d0 4374 4374
/dev/dsk/c18t5d0 4374 4374
/dev/dsk/c19t6d0 4374 4374
/dev/dsk/c18t7d0 4374 4374
/dev/dsk/c19t8d0 4374 4374
/dev/dsk/c18t9d0 4374 4374
/dev/dsk/c19t10d0 4374 4374
/dev/dsk/c18t11d0 4374 4374
/dev/dsk/c19t12d0 4374 4374

many thanks.

[TTr · Accepted solution]

Without getting more details I would say that you have an I/O bus issue right now probably because of overstriping. Striping spreads the I/O on multiple physical disks to take advantage of the I/O bandwidth of the added spindles. However all these spindles are sharing the same I/O bus (the same two I/O buses in your case) There is probably a lot of queueing happening in your server in trying to update all these spindles at once.

You should experiment with using fewer spindles in your striping.

Also did you use extend striping or regular (aka KB striping, aka "-i -I") striping.

I would say that even with 15kRPM disks you should not use more than 4 striped spindles in your LVs (2 spindles per controller).

If you have the flexibility, experiment with different number of spindles.