Seeking a beast Dell server

[itbnorris]

I need to upgrade my database server, and was hoping I could get a couple opinions from people here.

Ok, I've got an 80GB Oracle9i database in my group that supports some 200 users and runs on Windows 2003 Enterprise.

The server is a Dell Poweredge 6600 w/ dual 1.4 GHz processors, 4 GB DDR memory, and 8 73 GB drives in RAID 5.

We are consistantly over 70% processor time.

The server I've been looking at buying is a Dell PowerEdge 6800 w/ Windows 2003 Enterprise, quad 3.66 GHz processors, 1 MB cache, 667 Mhz FSB, and 10 73 GB drives.

In addition to your opinions I was hoping to ask what the advantages are of having a Secondary controller? and an idea of what internal and external channel means.

I appreciate any and all opinions.

 

[technome]

Nice server choice...

I don't think a secondary raid adapter will help. 10 drives divided over a dual channel raid adapter is just below the saturation point of u320 DC raid, if it were more drives maybe a second adapter would benefit. If the setup had >10 drives, LSILogic, OEM provider for Dell has a 4 channel adapter which would be the better choice. Any added cards, raid or otherwise, adds IRQ overhead, so you are better off with a single card.

For a database you would be better off with raid 10, faster than raid 5, as there is no parity creation overhead. I have no problems with raid 5, nearly all of my clients have it, running SQL, all are quite pleased. Most have 3 Ghz servers, single processor, under 100 users..cpu go up to 14%. The cpu speed/newer mobo should alleviate the processor utilization.

Make sure you have plenty of ram, 15k SCSI will make a difference, especially since the server is for a database. Personally I would purchase the bare minimum number of drives off Dell (2), and purchase the remainder off the Internet..5 year warranty versus 3 years off Dell. To me an added two years is worth a $100-$125.00/drive

Drives

http://www.rubyskytech.com/ProductInfo.aspx?productid=373453LC-XX5N

I get a kick out of the Dell CPU cache options, 8 Meg cache would only add minuscule speed, at best.

Internal channel should denote a ZCR (zero channel raid), which uses the onboard scsi interface. Addin cards have the scsi interface on the card.

How a ZCR stacks up against an addin card, I have never found any comparisons, seems like a guarded secret. I have not seen the specs for the 4e, but Lsi's last entry had basically the same co-processor,same speed, for the ZCR and the full addin. In years past the ZCRs performed well below the addin cards, as the ZCRs used the mobo cpu and ram, this is not the case with the newer ZCRs, they have there own co-processors.

 

[technome]

Last paragraph correction...
"but Lsi's last entry had basically the same co-processor,same speed, for the ZCR as the full addin card."

 

[jkupski]

Allow me to second RAID10--the performance improvement is substantial, and the array can potentially survive multiple drive failures--as many as n/2, assuming the right drives fail...

As far as internal/external channels on RAID controllers go, internal channels are for your internal drives, while external channels are for things like disk enclosures.

Also, instead of 8 73GB drives, you might be better served by going with 2 18GB drives (OS, RAID1) and 6 73 GB drives (Data, RAID10) which should give you better performance. In an ideal world, you would also have the OS container on its own channel, but given that the 6800 split backplane is 2x5, that doesn't seem particularly feasible.

 

[technome]

Allow me to second RAID10--the performance improvement is substantial, and the array can potentially survive multiple drive failures--as many as n/2, assuming the right drives fail..."
Jkupski, you are correct but Murphy's law hangs over me, so I only count on the one disk failure. With a large number of drives, I try to get a hotspare in the lot or at least a coldspare in storage.

Generally I build my own servers when a large number of disks are required and use this fantastic case...

http://supermicro.com/products/chassis/pedestal/800/SC850P4.cfm

With these drive racks...

http://supermicro.com/products/accessories/mobilerack/CSE-M35S.cfm

With an Lsi u320-2 or u320-2x (oem perc)...
I have tested the setup of having the OS on raid 1 (15k scsi) and the data on another array set (15k scsi) and the setup is not faster. Even with a raid 5 setup with two partitions, one for the Os, the other for data, the raid 5 setup is faster for the OS then raid 1, as the reads are so much more superior with more than 4 drives. Have also tried it with a separate 2 channel standard Adaptec SCSI u320 adapter for the OS on duplexed disks and the raid adapter for the data, still raid 5 had better performance for the OS.

Either way it is better dividing the drives over two or more channels, as evenly as possible.

 

[itbnorris]

Fantastic replies all. I appreciate the help.

I have a question though that is somewhat off topic, but a curiousity of mine. Can you add disks to RAID 5 (or 10) after creation? Or would you have to rebuild...

 

[technome]

The Lsi /perc do not natively allow expansion of a redundant disk volume. Creating another raid volume with the adding of disks is not a problem.

Check this out.

http://www.microsoft.com/technet/itsolutions/msit/operations/diskpartnoteonIT.mspx

HPs solution

http://h18006.www1.hp.com/products/storage/software/svg/qa.html

There are other utils out there, and plenty of horror stories, when they fail.

Off topic.. with as many disk as you have I would purchase a spare disk to have on hand, even with a service contract.

I would research references to Oracle and stripe size. The 64k default may not be the best size. General 64k is the best size for a general use server with the Lsi adapters, but specialized database server such as yours may benefit from a different size. If you find info it must reference Lsi/perc adapters, as different adapters vary as to the best stripe size.