Opinion on SCSI configuration

[starz716]

I have a Gateway 6400 server with a dual onboard SCSI controller. I need to use it to Run Windows 2000 Server, an application accessed through terminal services, and a Web Server for secure data access. I am trying to research SCSI, an area I am weak on, and figure out the best bang for my buck configuration. I currently have an 8 Gig IDe and a 9 Gig SCSi on the machine, but am looking to configure it for fault tolerance and speed. The following are the components I need to install:

O/S Windows 2000 Server SP2
System Page File
Applications, (Specifically, the one business application, and perhaps a few custom written ones)
Data Files

I read a rather lengthy article that suggested not storing data on the more costly SCSI side, but these data files are heavily read/writen to, unlike word docs or files like that.

I want to have fault tolerance on the OS (perhaps with more than one drive that can be switched out if the OS fails for any reason and be back up in less than 5 minutes) but more so on the data files. Also, since I will be running several concurrent connections on the Terminal Server, seek times may be a premium.

What effect would partitioning the SCSI drives have on performance? In other words, would it be worth it to partition an 18G SCSI into 3 partitions, only to then have them be used as one fault tolerant logical drive? The data files that I need to access would not foreseeably exceed 1G, and are currently about 100MB.

Any ideas would be greatly appreciated!

 

[bwass24]

In order to have any degree of fault tolerance you need to use more than one drive. With 2 drives you can use mirroring (one drive is a simultaneous mirror of the other) and you will (almost) never have disk down time. With 4 or more drives you can use RAID5 (data and error correction info are striped across all of the drives) which has both a speed advantage and a (lesser) degree of fault tolerance.

If you're not supposed to store data on SCSI drives then what ARE you supposed to store on them? That article seems a little strange. SCSI drives are what's used in virtually all storage arrays and high performance systems. Even fiber channel drives are SCSI.

 

[starz716]

Let me clarify,
The article was a good one, and the point of the author was that there is a definite performance advantage with SCSI drives, but that an environment with BOTH SCSI and IDE could help you to make a good compromise between cost and storage. My real conundrum is in which of the aforementioned areas (OS, Pagefile, Apps, Data files) to make the sacrifices in performance. While storage is not a huge factor with me, COST IS. I would prefer to have a RAID 5 array, but I cannot afford to purchase 5 SCSI hard drives at this time, no matter how small (unless you know of a deal for me). Just to clarify, you said you must have more than one drive to have any sort of fault tolerance. Do you mean one PHYSICAL drive, or would it suffice to partition one physical drive, albeit with a loss in performance.

 

[Pariah]

RAID 5 only requires 3 drives. But if you require top notch read and write performance, that will require a top notch SCSI RAID controller which doesn't come cheap. In order to create a fault tolerant environment you have to have at least 2 physical drives, partitioning one will not work. If creating a RAID array within a drive were possible, a loss of performance would be a considerable understatement. Best case scenario, performance would be half of a single drive. Fault tolerance in that scenario would only protect against file corruption, if there was an actual hardware failure you would be up the proverbial creek without a paddle.

 

[mastertech01]

With 3 drives you can create a software raid 5 using the dynamic disk features of Windows 2000 server. It may not perform as well as a hardware SCSI raid controller but would offer fault tolerance with about 2/3 of the drive space usable. That would be better than mirroring which is only 50 percent efficient.

 

[Lytech]

Thank you all for your replies! I truly appreciate any opinions I can gather on this subject. What I am truly asking for here is, where would you put SCSI drives vs IDE in my situation? Which drives (SCSI or IDE which I can use windows to configure as Raid) would you configure as RAID. I am looking to aquire more SCSI drives, and maybe another IDE drive, so that I can feel confident that if something were to go wrong, I could minimize downtime. One method is to create a duplicate boot drive in a drive cage that I could slide in\out if the first one won't boot. I could also partition the boot drive, make both partitions bootable and use a floppy drive with the boot.ini ARC path set to the alternate drive, thus stick disk in and reboot, you're OK.

The big thing here is, I had always planned on putting the Data files on the SCSI drive, (or drive array in a raid 5 for speed) so as to have the quickest access to those data files, but my reading of that recent article caused me to rethink that strategy, as I may be under-rating the importance of an OS and apps on SCSI. I cannot, alas, afford to do both.

So what I am asking of this obviously VERY intelligent group of people, is that in your experiences, how important would each of these componenets rank and which ones, by priority, would you be more likely to put on SCSI over IDE due to performance!

 

[mastertech01]

Lytech, You really arent specifying how large the database is going to be, or if multitasking is going to play a large part of your usage. Im partial to SCSI, so I would just tell you to put your OS on the 9GB SCSI drive, and buy 3 more SCSI drives for a software raid 5 setup for the best economy. Just figure the total estimated size of your database and divide by 2 then buy 3 drives of approximately that number. So if for example you estimate your data base to be 36GB, then you need 3 18GB drives to make a 3 drive raid 5 array. Thus you would have a 9GB boot drive, and a 36GB fault tolerant array. Then put the IDE drive in your sisters computer... <------SCSI PHREAK..

 

[Lytech]

Actually, I did specify the size of the database. While at present it is only 100MB, I do not foresee the need (w/in the next 5 years) for it to grow any bigger than a GIG. Your proposal is interesting, and helpful, but the cost of THREE scsi drives is a deterrent right now. My controller (built in to Mobo) is LVD and 160 compliant, so I would most certainly want to get the same in a SCSI drive (68 pin) and in looking around, it does not look cheap! Also, this means that the pagefile would have to be placed on either the Data file drive(s) or the OS drive(s). Further, no fault tolerance for the OS is available in this configuration. I could have the one SCSI drive partitioned into 2 partitions, and have duplicate installations on each of these, which would be somewhat acceptabel (and I could then use the IDE as a last resort backup if the SCSI should fail completely) but then I would need at least an 18G SCSI, as 4 Gigs is not enough for OS and apps, while 9 Gigs might be! Hmmm.....

 

[Pariah]

With such a small amount of data, it would be a waste to buy multiple drives. Hard drive speed is pretty irrelevant because a 100MB database would easily fit into RAM if you have a decent amount. Just buy a single SCSI drive, make 2 partitions, 1 with OS and apps, second with the data. You can ghost the OS apps paritition onto a small cheap IDE drive as well as copying your db there. At 100MB you could copy it to a cdr everything single day at it would still be far cheaper than RAID'ing SCSI.