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Slow performance in AutoRAID 12H

Valarie Lim
Advisor

Slow performance in AutoRAID 12H

Good Evening,

I have a autoRAID disk Array which is fully populated with 18Gb 10000rpm disk.
There are six LUNs being configured.

When i run iostat between my backup timing,
the statistics shows that a maximum 3MB/s per LUN whenever reading from these LUN is needed.
When two LUN read, there is an imbalance of throughput of 7MB/s and 3MB/s.

1) May I know if the maximum throughput of AutoRAID is 10MB/s?

2) Is there anything wrong with my configuration?

Thanks!
3 REPLIES
David Navarro
Respected Contributor

Re: Slow performance in AutoRAID 12H

Hi,

Are you using the same scsi interface for backup that LUN's?


Bill McNAMARA_1
Honored Contributor

Re: Slow performance in AutoRAID 12H

FWD scsi throughput can get up to 14MB/s if you're lucky.

As mentioned, check your lun access configuration (LVM)

arraydsp -c
where is returned from arraydsp -i
Mark the controller SCSI IDs from the output.


ioscan -fnkCdisk
will show you the paths to the LUNs. If you have two controllers you will have two access routes to the LUN. One throu X and the other thru Y.

Access half through X and the other half through Y.
This is done via LVM vg configuration:

strings /etc/lvmtab
.
.
/dev/autoraid
/dev/dsk/c1t2d1
/dev/dsk/c2t3d2
.
.


ie:
c1t2d1 LUN1 thru t2 (scsi id 2)
c2t3d2 LUN2 thru t3 (scsi id 3 on a different bus - c2)
(It doesn't necessarily have to be a different bus but you're not sharing bus bandwith if it's like this)

So you access LUN2 through a different controller (and bus) than LUN1 and can realistically get up to 14MB/s simultaneously.. giving 28MB/s transfer to the array.

Note that the LV, thus the filesystem) can be spread across those two LUNs (which are LVs) using the lvcreate -i 2 -I 64 option.
Thus your filesystem can get faster than rather having your LV on one PV only
lvcreate -L 500 /dev/vgauto
only one PV for the lvcreate here. (well if there's not space on the PV1 (LUN1) it will continue onto PV2 (LUN2))

Later,
Bill




It works for me (tm)
harry d brown jr
Honored Contributor

Re: Slow performance in AutoRAID 12H

The performance specs are a max of 20mb/s:

http://www.hp.com/products1/storage/disk_arrays/midrange/12h/specifications/index.html

Do you have ONE or TWO controllers? If you have TWO, do you have alternate pathing (use seperate IO path) to the device (disk/lun) per VG?


live free or die
harry
Live Free or Die