Archived posting to the Leica Users Group, 2008/08/21
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Gary, Sounds like a similar philosophy to my first PC experience. The Xerox system used two 8-inch floppies, one for the CP/M OS and the second for the application and data. Jim Nichols Tullahoma, TN USA ----- Original Message ----- From: "Gary Todoroff" <datamaster@northcoastphotos.com> To: "Leica Users Group" <lug@leica-users.org> Sent: Thursday, August 21, 2008 12:41 PM Subject: Re: [Leica] RAID controllers? > Very thoughtful and informative reply, George. Would love to debate over a > beer sometime! My philosophy about PC's in general is that they are like > sports cars -- lots of horsepower but not much torque. So you never load > down one PC with too many tasks.My network has PC's dedicated to specific > tasks: Server as just a fat disk (the RAID5), Photoshop workstation has > powerful CPU and dedicated fast SCSI scratch drives, film scanner > workstation is also used for e-mail, word processing, etc, and the Office > PC is for Quickbooks. This is all a lot less expensive than it sounds, > since I have mostly rotated older PC's into the tasks that don't need much > horsepower. > > In the same way, I like to separate programs from data - probably leftover > from midrange and mainframe computer days when "libraries" kept an > organized approach, very much *unlike* Windows. Perhaps that is why I like > the OS separate from data on my server -- data only on the RAID, OS on the > IDE (or is it SATA?) drive that runs the computer and will be there no > matter what happens to the RAID. I also like the performance advantage > that puts the OS overhead on one disk, while the data read/writes are the > only function of the RAID. > > Gary Todoroff > > At 10:36 AM 8/20/2008, you wrote: >>Spencer Cheng writes: >> > A bit late but here is my experience. >> > [...] >> > I agree with those who says the OS should not be part of the RAID >> > array if for no other reasons other than that RAID5 recovery can take >> > a long, long, long time. If you have a deadline, the last thing you >> > want to do is to sit there and wait, and wait, and wait, and pray that >> > the OS can be recovered so you can actually boot your PC.... >> >>I agree with Spencer, RAID is not a replacement for separate backups, >>preferably taken on a regular basis and stored offsite. Add >>catastrophic hardware failures to the list of coffee, soda, fire, and >>theft. >> >>But I guess that I now disagree with Spencer _and_ Gary. Hopefully >>this doesn't make me disagreeable.... >> >>If you have a redundant disk setup, RAID 1 or RAID 5 or RAID 6 or..., >>and you lose a disk, that volume should continue work, albeit possibly >>more slowly. That's what RAID's do. There's no mystery about it, no >>praying, and no waiting for it to recover. When you replace the >>failed drive the system will spend a *lot* of it's time "resilvering" >>the mirror aka rebuilding the array, during which time performance >>will _suck_ but the volume will still be available. >> >>It's not as if it's gone away and you're hoping that the recovery >>process will somehow magically bring it back. All of your data is >>still there and still available. No praying involved. If you don't >>believe that your RAID can survive the loss of a single disk, you >>probably haven't played with it enough and I'm not sure what's it's >>giving you. >> >>If you're thinking about setting up a RAID, you really owe it to >>yourself to experiment with it before you have all kinds of data on >>it. Read the manual. Set it up. Read the manual. Power down and >>disconnect a drive. Reboot and see what happens. Read the manual. >>Power down and reconnect the drive. What do you need to do to >>reintegrate the drive? Read the manual. Disconnect two drives. >>Etc.... Once you're comfortable with it as a tool, then you can put >>your valuable data onto it. >> >>Various RAID strategies offer varying degrees of redundancy. A >>two-disk mirror can survive the failure of one disk without losing any >>data. A three-way mirror can survive the loss of of two disks. A >>four-way mirror could survive the loss of three. A simple RAID 3 or >>RAID 5 can survive the loss of one disk, lose two and the whole >>thing's toast. There are various flavors of RAID 5 that offer more >>redundancy, called things like RAID 6 and RAIDZ2 and..., and which can >>survive the loss of multiple disks. >> >>Just as when you have a disk die in a single disk setup and you can >>sometimes peel some/most of the data off of it, you can sometimes peel >>some/most of the data off of a completely FUBAR'ed RAID. But that's >>not the same thing that happens when they lose a single disk. >> >>You should think about the risk of two disks failing in your >>situation. You might think that disk failure is a long shot and that >>two failures is well nigh impossible. On the other hand your first >>disk might have failed because you keep the machine in the closet so >>you don't have to listen to the fans and you've overheated it. That >>could make your second disk more likely to fail too. Or maybe you >>bought both of the disks at the same time, they came out of the same >>box, and the FedEx guy dropped it on the way to your front door. Or >>they were both made on the Monday morning following Mardi Gras. If >>you want to see some real disk failure numbers w/out marketing crap, >>check out this study the Google crew did. >> >> http://labs.google.com/papers/disk_failures.html >> >>There are lots of solid reasons to keep some data on a separate hunk >>of storage from other data (and the OS is really just another hunk of >>data). Performance. Manageability (you don't want the fact that your >>kid filled up his hunk of the disk with mp3's and videos to keep you >>from being able to work with your images). Move-ability (you'd like >>to be able to take the hunk with you somewhere else w/out lobotimizing >>the machine. Sometimes you handle this by using a separate disk >>(either a real one or a virtual one constructed from a RAID). Other >>times you partition a real/virtual disk into hunks and use them >>accordingly. One or more of these reasons might encourage you to put >>your OS on a separate disk, but they don't otherwise mean that you >>shouldn't keep everything together. >> >>If you have a mac that can hold multiple disks, and you're willing to >>put two disks into it, I'd say that you really should set them up in a >>software RAID 1 and that you should put the entire kit-and-caboodle on >>that RAID. My money's where my mouth is, it's how I run my machine. >> >>If you can put more disks into it, then it's a more complicated >>decision. Meet me in Oakland, CA and buy me a beer and I'll babble >>about it until the beer's gone.... >> >>Sheesh. When did I get so long-winded???? >> >>g. >> >>_______________________________________________ >>Leica Users Group. >>See http://leica-users.org/mailman/listinfo/lug for more information >> >> >>No virus found in this incoming message. >>Checked by AVG - http://www.avg.com >>Version: 8.0.138 / Virus Database: 270.6.6/1624 - Release Date: 8/20/2008 >>7:11 PM > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >