View Full Version : IDE vs. SCSI recomendations?

02-23-2001, 12:57 PM

I am about to upgrade an email server to a new G4. The current machine is a G3 work group server with two 8GB SCSI drives, and the email app (First Class) writes to both.

My questions: Can I use two 30 GB ATA/100 drives in the new G4? Can ATA drives be mirrored, or do I have to to SCSI? If ATA will work, what drives/contollers are recommended? Reliability and disc capacity are more important than speed.

Thanks in advance for any suggestions .

02-23-2001, 01:20 PM
If you are looking for reliabilty, SCSI is the ticket.

I have two 9Gb Cheetahs in a raid 1 running my email server.

An Atto SCSI 3 board with dual 9 or 18 GB drives in a raid 1 is hard to beat.


02-23-2001, 08:27 PM
Jorge has it right. There is no point (IMHO) to RAID any IDE drives. To look for backup and stability in inferior drives is a little goofy. IDE generally have lesser warranties, and that is not a good sign. A RAID mirrored with IDE drives is a decent solution, but SCSI is the paragon of reliability. Configured well and maintained, a SCSI setup will outlast your needs. I just sold a 6 year old RAID that still worked terrific. And it still is 6 months later. I wouldn't even think about keeping 6 year old IDE drives around.

If this is a server taking hits from several clients, I would demand the multi-tasking and scalability of SCSI. The new G4 has internal ATA, of course. So you could use IDE drives right off the bat. But to my knowledge, SoftRAID is the best RAID utility out there and it does not do ATA. Not sure if something is in the works, as I usually only pay attention to things that really affect me or I think soon will. Magician or Louie or someone with more SoftRAID knowledge should be along soon to give you the facts.

Is there a financial consideration in this? That is a good place to start. If you are planning on getting a new G4, you would need a good SCSI card (get it here, please) and some drives. Apple is not as quick or versatile in terms of support as some forums out there. Namely this one. And Apple has a slight tendency to charge a little more than most places and stick in a varied assortment of actual drives. If money IS a consideration, IDE would be logical. If it is a flexible position, then go SCSI. If you need particulars...you came to the right place.

02-24-2001, 03:59 AM
Thanks for the info. . . I had checked with some other sources and everyone seems to be in agreement - bring on the seagates!

While I have your ears (eyes?), anything special you guys would recommend either to configure or to maintain the drives? The mac that this will replace runs until it crashes. Not my idea of good planning.

I was volenteered to replace/maintain this machine, so now I get to learn on the job (and have about 130 people waiting if/when their email goes down). My goal is to have email up 99% of the time. Thanks again.

02-24-2001, 11:58 AM
In your setting, you'll never regret going with a SCSI subsytem. A mirrored array will provide immediate functional capability in the the event of a catastrophic loss of one of your drives, but it is not a substitute for a good backup scheme. Depending on how bulletproof you need to be, the safest scheme would be to backup to a tape drive and a series of rotating tapes stored offsite. The Retrospect application is a must have for any backup scheme, whether you do it over the network or to a local backup drive. It is the Rock of Utilties and can give you software compressed backups at up to 2:1 compression on its own.

One other option would be to retain the G3 server as a backup server of sorts, stripe the two smaller drives in a RAID 0 for speed and use Retrospect to backup to the stripe over the network at night. In the event of a major failure of the G4 main systems, you could pull the SCSI subsystem and put it into the G3. I would also put a system and basic maintenance tools on the ATA drive in the G4 and use Retrospect to dupe this to an ATA drive on the G3. That way you can pull maintenance from or on either server. I think this is best because many fixes can't be performed by software on the drives that have the active startup system or that hold the utility app itself. Some fixes also cannot be performed on a network drive mounted on the desktop.

Basic tools I beleve in: Retrospect, DiskWarrior, Norton Utilities, TechTool Pro, Disk First Aid.
Through your network admin or your own monitoring tool, you probably would want some way to look at traffic on your server and to tweak parameters. Other guys with more network experience will be of more help here.


02-24-2001, 10:53 PM
ok...let me see if I can add anything. You have already received some very good advice.

one question I have is, are you married to First Class? If not, you may want to look at EIMs. It is very simple, works well, and while Qualcomm tech support is about as fast as one of Darin's bowel movements, there is a superb mailing list which is haunted by the actual programmer of the application which compensates hugely.

as far as hardware is concerned, I agree that a RAID 1 using a pair of Cheetahs and an ATTO with SoftRAID is the right way to begin. Here's what you need to start:

1. ATTO (http://www.macgurus.com/shoppingcart/showrampage.cgi?attoboards.html) UL3D or UL3S.
2. A pair of LVD Cheetahs (http://www.macgurus.com/shoppingcart/showrampage.cgi?mg_hdseagates.html).
3. A license for SoftRAID (http://www.macgurus.com/beta/obj_show_page.cgi?mgscsiraid.html).
4. a GD1200 (http://www.macgurus.com/shoppingcart/obj_show_page.cgi?mgscsiteflonintcables.html) internal LVD TPO Cable
5. a GD6299 (http://www.macgurus.com/shoppingcart/obj_show_page.cgi?mgscsiterminators.html) Diagnostic LVD Terminator.

this hardware will give you tier 1 redundancy for your email accounts.

as DogSM points out, SoftRAID doesn't support IDE directly, and the various IDE PCI host cards emulating SCSI that are available are not robust or trustworthy enough, IMO, for something like running a mail server.

as MM points out, you need to use Retrospect to further backup your data. Rather than pointing Retrospect directly at a RAID volume, whether RAID 0 or RAID 1, I would prefer that you back up to a dedicated IDE drive in the G4, and then point Retrospect at THAT drive for backups to tape.

Darin can attest that Retrospect can be very stupid when backing up. It doesn't check to see if your volume is actually valid when it backs up your data, for example. He lost a drive in a RAID partition, which left it invalid, and then Retrospect backed up the empty, invalid contents of the volume to his backup, hosing him completely.

So. The way we do it here, and the way we recommend others do it, is to simply execute a drag-copy in the Finder periodically throughout the day, and before you walk out the door in the evening, from the RAID 1 to your IDE backup drive.

At the witching hour, or whenever you schedule Retrospect to backup, it will grab the data off your IDE drive, and then take it to another machine, like a server with a dedicated network backup drive, and THEN to tape, which gives you several levels of data security.

firstly, you have the built-in redundancy of the RAID 1 itself, which gives you pretty much up-to-the second backups in event of a drive failure. And using SoftRAID is key, as you can continue to hit the array even when the array is rebuilding or clearing an out of sync condition. In other words, if a drive fails, you swap it out, and fire up the server again, and put it back online. While users are hitting the disk, it is rebuilding in the background. This is key.

secondly, you are manually backing up your RAID 1 to a fixed drive on the same machine, so in the event both drives go up in flames, you still have a local, immediate backup which will be as current as the last time you dragged a copy onto it. It can actually be faster, if you are afraid to trust SoftRAID to rebuild in the background, to simply remirror a pair of replacement drives and then drag the last backup from the IDE drive to a new mirror. Regardless, it gives you some flexibility. I would use a separate IDE drive for this--not the one you boot from. That's just me.

thirdly, you backup the local backup on the IDE drive in the machine to a server on the network, giving you a completely separate copy on another machine, maybe even on another floor of the building, or at least a different room. If someone comes in with AK47's blazing, maybe they won't destroy the machines in the other room. This is the backup that should happen in the middle of the night, as it will take a little longer. You are backing up changes to a data set in the middle of the night remotely over 10BT or 100Bt ethernet, you see.

finally, the copy of the data on the network server volume should itself be backed up to VXA-1 tape. You should grab this tape every morning, after checking the Retrospect server logs, and put it in your briefcase. Replace it with a fresh tape. Do this every day, and you will take home with you the previous day's backups every night. If the building burns down, guess what? You are a hero. You may be missing 24hrs worth of data, but losing a day's worth of email is not nearly as horrific as losing ALL of it.

hopefully this isn't too confusing. I'm still a little mad that I don't get to see Charlize Theron naked tonight. I'll bail now and let others have their say, as well.


[This message has been edited by magician (edited 24 February 2001).]

02-27-2001, 08:36 PM
Wow. . .thanks to all for the great info. I am currently using retrospect. I feel better knowing that vetrans find it to be less than comforting; I was afraid it was just me.

Yes, for better or worse, we are sticking with First Class. Although this is the first "real" email I have been involved with, I am very happy with the product and the support (except the fact that they have stopped updating for Mac OS at 9.0.3 - waiting for OSX).

Thanks again to all for the help.

02-27-2001, 10:37 PM
fyi... I just nuked that other thread as per your statement.


02-28-2001, 12:15 AM
Mag's advice is well taken and sure does put the fear of space monkeys into one...

My back-ups are to DAT nightly, network to VXA weekly.. but I'm backing up several RAID 0 and one RAID 1 array.. now - I do recall Darin's horrific problem from a few months ago and that has me pondering the IDE local backup drive idea, more seriously now...

03-13-2001, 12:41 PM
After jumping through the hoops with our accouting dept, I ordered and received the SCSI setup. I installed and terminated the drives; the discs mounted fine. Thanks for the prompt shippment.

Now the bad news. . .one of the drives makes some noise. It sounds like it is reading/writing, except about half as loud, and it changes pitch, and comes and goes - even though there is no activity, and no data has been written on either drive yet. It somes like somthing mechanical as opposed to an electrical hum.

I thought it was a vibration or perhaps a fan, so I checked that everything was secured. Then I removed one drive at a time. The first seagate and the stock maxtor ATA are both perfectly quiet. The second seagate is the source or the noise. With the second drive unplugged, the G4 makes no unusual noise.

I removed the suspect drive and started the machine with the drive in my hand (to isolate it from the case) and the noise is still there. I can feel a slight vibration in the drive.

Is this normal? It does not give me a warm and fuzzy feeling. . . does this qualify as a manufacturing defect? Although the drive appears to working correctly, should I trust it for the next several years in such a critical server? What are my options?

03-14-2001, 03:35 AM
definitely swap it out. Just email deb@macgurus.com and have her take care of it for you.

I see no point in running any risks, right?

sorry for the hassle!