ProLiant DL380 G3 I/O Bottleneck

[Andrew_235]

Hi,

Guy - To be honest, I am not sure. I believe the drives may be in simplex mode. What is the easiest (and least painful) way to check? If it is not, how do I go about setting it up? The documentation is very thin. With Ultra320 drives, running at 320Mb/s, will duplexing allow through put of 320Mb/s (2 x 160MB/s)? How does this work with multiple drives on the channel?

Doug - Will have a think about adding some more drives and sepearting things over 3 x RAID 1 sets.

Can someone explain the simplex/duplex method and how it will alter our performance?


Andrew

[Prashant (I am Back)]

Hi,

See the snap shot for conenction. You are using two cotnrller to incrase the performace.

PCI duplex - All internal hard drives are split between two SCSI controllers. The embedded Smart Array 5i Plus Controller is connected up to two hard drives on one SCSI bus and the optional PCI array controller installed into an available PCI slot controls up to four hard drives on the other SCSI bus.

Regards,
Prashant S

[Gus Kwong]

Hi Andrew

>What is the easiest (and least painful) way to check?

The way I'd check is to see if the SCSI terminator is in place at the back-plane --- if not, then it is simplex. If you bought the server new, then it should come with a terminator and a spare SCSI cable.


>how do I go about setting it up? The documentation is very thin.

Unfortuantely, I don't know if there is an easy way to migrate the RAID set from simplex to duplex... not unless you Ghost the server up-the-way, recreate the RAID set in duplex, and Ghost it down again. This document should be useful (do a find on Simplex and duplex) http://h20000.www2.hp.com/bizsupport/CoreRedirect.jsp?targetPage=http%3A%2F%2Fh200007.www2.hp.com%2Fbc%2Fdocs%2Fsupport%2FUCR%2FSupportManual%2FTPM_303130-003%2FTPM_303130-003.pdf


>With Ultra320 drives, running at 320Mb/s, will duplexing allow through put of 320Mb/s (2 x 160MB/s)?

Since hard drives cannot really reach 160MB/s, a dedicated SCSI channel (at 160MB/s) will be more than adequate for just one drive. So if you mirror 2 disks on 2 separate SCSI channels, then you don't have to worry about hard drives fighting for the SCSI channel (not until you have more than 2 drives on one channel).


>How does this work with multiple drives on the channel?

Quite simply, the Drive Cage uses the shared channel for all disks --- so in Ultra3 mode, if all 6 disks are writing at the same time then each disk could be hit as little as 26MB/s.

In duplex mode, the drive cage is physically separated so that slot 0,1 is in one isolated area, and slot 2,3,4,5 in another area. They will simply be assigned with different SCSI ID as well as the controller ID. But the DL380g3 doesn't care, and you can simply select appropriate disks when you create your RAID sets.

Gus

[Martin Forster_1]

you do not need to joke arround with the bus performance to disk. event fastest Harddisk i know does not need that performance. Its more for 14 Drive boxes or so.
You will see the most performance gain from the BBWC.
Next Step is to separate the transaction logs. 1st logicall 2nd on a own raid.

And make sure that memory is not your bottleeck, because when you limit the amount of memory for the SQL Server. Paging lost its indication for a memorybottleneck.

Regards.