Any idea about improvement with HPUX fiber channel technology

[xav]

Does anyone has already implemented HP solution type 5470 ( ex L100 ) with fiber channel technologie.

And if so, could you give me some informations on what kind of improvement you got.

Our App is client server mode interactive ( 100 user ). And some background process ( calculations ) .

We are using 8 DB with lots of transactions on three of them.
Most of the time use to spread our db's over 4 or 3 disk depending on our customer money. Separating bi when it's possible. using -B, biw ....

We experiment performance problem's due to disk access.

I'm searching the way to improve this and fiber channel seem's to be a good way !

 

[ron]

Does anyone has already implemented HP solution type 5470 ( ex L100 ) with fiber channel technologie.

And if so, could you give me some informations on what kind of improvement you got.

Our App is client server mode interactive ( 100 user ). And some background process ( calculations ) .

We are using 8 DB with lots of transactions on three of them.
Most of the time use to spread our db's over 4 or 3 disk depending on our customer money. Separating bi when it's possible. using -B, biw ....

We experiment performance problem's due to disk access.

I'm searching the way to improve this and fiber channel seem's to be a good way !

Look back through the ProgressTalk archives (under "FCAL", perhaps), Xav --- you will find a very good thread on this subject ... including some very helpful remarks from Gus (at Progress). The consensus was that Fibre Channel IS NOT a panacea!

I guess it's an obvious statement - but you will only get the level of performance you're prepared to pay for. Spreading DB i/o over 3 to 4 discs looks like a bit of a problem ... in my experience DB performance is HIGHLY sensitive to the number of disc spindles: the more the better.

Why not share some more details about your "typical" configurations, Xav. There are several professedly learned DBA-types in this forum who like to offer help with tuning issues!

Ron.

 

[toby.Harman]

Hi All

As one of the "several professedly learned" people (duh - what's that then?!) I'll stick my AUS$0.02 into the pile and see what happens.

I couldn't see details on the L100 system so I'll stick to general comments and comments about the Compaq kit I know a bit about.

FCAL - Fibre Channel Arbitrated Loop. This means that when you want to talk to a disk on this loop it has to select that disk and tell it to pay attention before it actually talks to the disk. This means that effectively each disk access is prefaced by a logon request for the disk and suffixed by a logoff.

You can get disks that are actually Fibre Channel connected, but the more you spread your I/O between the disks, the more bandwidth you lose to logon and logoffs for the disks themselves.

One important thing to remember about Progress. It has a tendancy to produce large numbers of small writes in a high volume database system. This means that Progress in particular has issues with FCAL.

I played with a Sun implementation of FCAL and got very medium results... VERY medium indeed!

A better solution is the Compaq version (which is now HP and may be what you are talking about) whichh relies in a switched fibre network to talk between the host and a dedicated disk controller. Behing the disk controller are a number of SCSI buses that have a number of disks on each.

Compaq claimed 100MB (bytes - not bits) per second between the controllers and during our benchmarks we were only able to achieve 98-99MB/s, so they aren't far off. This then passes through a controller that converts Switched Fibre protocol to SCSI and writes to the disk.

In short - Switched Fibre good, FCAL bad!

Ultimately you will always have a tradeoff between big boxes of storage to which you can attach multiple hosts and achieve flexibility, and dedicated storage which is present for only one host.

With big box storage you have little control over what happens behind the scenes in terms of internal I/O conflicts and problems.

With little dedicated storage systems you have problems migrating disk space between hosts.

Given that HP now own Compaq and have all their technology - I would be inclined to go back and check the full range of storage on offer and get a techical pre-sales guy onsite for extensive discussions!

Good luck, and enjoy your walk in the minefield of storage, NAS, SAN, FCAL and all the other acronymns out there.