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disk performance on rp7410

 
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Naoyuki
Advisor

disk performance on rp7410

I have a hardware thing question.

Let's say I have two disks connected to separate scsi card.

0/0/6/0/0.8.0 sdisk DEVICE /dev/dsk/c2t8d0 --- diskA
0/0/0/3/0.5.0 sdisk DEVICE /dev/dsk/c0t5d0 --- diskB

In this case, is it possible that diskA slows down when diskB is busy?
I thought that if connected to separate scsi card, those disks don't interfere each other, so there is no slowdown.
But I noticed diskA might have been very slow when diskB was very busy.
5 REPLIES 5
Mark Grant
Honored Contributor

Re: disk performance on rp7410

These two disk do not interfere with each other. To track this issue down I think you need to see what is being written to both disks. It may be for example that an application working too hard on disk A is using too much memory, causing the system to swap to a swap device on Disk B. In this case you would see what you do but the disks are on two completely seperate SCSI busses so of themselves, do not interfere with each other.
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Saurav_1
Valued Contributor

Re: disk performance on rp7410

Hi,
i agree with Mark. To know the past performance of the 2 disks. install perfview.
Mostly it is installed you can try running the command "pv" on X windows display. because of high swapping some disks appear to give slow response. try to create some swap logical volume. on the other disk and set the same priority at original disk. Hope this solves ur problem.

Saurav
Stuart Abramson_2
Honored Contributor
Solution

Re: disk performance on rp7410

1. The rp7410/11i system has a command:

rad -q

2. rad -q shows you which i/o card is in which slot:

# rad -q
Driver(s)
Slot Path Bus Max Spd Pwr Occu Susp Capable Max Mode
Num Spd Mode
0-0-0-1 0/0/8/0 64 N/A 66 On Yes No Yes N/A N/A
0-0-0-2 0/0/10/0 80 N/A 66 On Yes No Yes N/A N/A
0-0-0-3 0/0/12/0 96 N/A 66 On Yes No Yes N/A N/A
0-0-0-4 0/0/14/0 112 N/A 66 On Yes No Yes N/A N/A
0-0-0-5 0/0/6/0 48 N/A 33 On No N/A N/A N/A N/A
0-0-0-6 0/0/4/0 32 N/A 33 On No N/A N/A N/A N/A
0-0-0-7 0/0/2/0 16 N/A 33 On No N/A N/A N/A N/A
0-0-0-8 0/0/1/0 8 N/A 33 On No N/A N/A N/A N/A
0-0-1-1 1/0/8/0 64 N/A 33 On No N/A N/A N/A N/A
0-0-1-2 1/0/10/0 80 N/A 33 On No N/A N/A N/A N/A
0-0-1-3 1/0/12/0 96 N/A 33 On No N/A N/A N/A N/A

My rp7410 has two cell boards, a 0 board and a 1 board.

c0t5d0 is on the "internal" card for the boot disk, DVD and tape drive. c2t8d0 is on the same cell board, but is connected to a SCSI (or fibre) card.

However the answers above are probably right. Your root and swap are probably on c0t5d0, and that could slow down system performance when high root access or swap.
Michael Steele_2
Honored Contributor

Re: disk performance on rp7410

Let's check the disk product number and Revisions Levels:

# diskinfo -v /dev/rdsk/c0t5d0

Vendor and product ID
Device type
Size (in bytes and in logical blocks)
Bytes per sector
Revision level

###########################################

SCSI disks on SCSI buses have target priorities. If there are other devices on the SCSI bus then priorities become an issue.

Target t8 in c2t8d0 should have the lowest priority while target t5 in c0t5do should be third highest highest priority. There are 16 targets. 7 is highet, 8 is lowest.
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Naoyuki
Advisor

Re: disk performance on rp7410

Thanks for the all replies.
I will check what's going on.