@ fjmi
Wenn ich ein Video heute nicht geändert habe, überschreibe ich auch nicht dessen Sicherungskopie. Du tust gerade so, als wäre Backup etwas, das einem täglich Ewigkeiten rauben würde - aber dem ist, solange man nicht tägliche mehrere GiB
neue Daten hat, nicht so. Für Leute, die selbst nichts konfigurieren wollen, bietet sich dann halt sowas wie Time Machine an.
Ich hab jetzt mal ein paar Blogeinträge von Robin Harris zu Desktop/Home-RAID rausgekramt, der zweite ist vermutlich der interessantere.
Desktop RAID is a bad idea
Jon Bach, who runs Puget Custom Computers in Seattle, explains
Why RAID is (usually) a Terrible Idea in his blog.
Breaks way more often than disks do
Jon notes that for some reason many of his customers come to him convinced that they need RAID on their home or professional workstations, and he tries to talk them out of it, often with no success. I imagine the conversation goes like this:
CUSTOMER: I want to spend hundreds of dollars on RAID.
JON: Well, we build and service hundreds of computers each year and we don’t recommend it.
CUSTOMER: Are you a communist? I want RAID. I want to spend the money. I want the hassle. I want the false sense of security. Give me RAID!
JON: Just to prove I’m a capitalist running dog I’ll take your money. But I still don’t recommend RAID.
CUSTOMER: Fine. Since we’re on the subject, what is RAID?
OK, so why is a non-communist against RAID?
Maybe because he’s part of the reality-based world. As he notes in his post:
Jon Bach schrieb:
. . . I estimate that anywhere from 25% to 30% of our customers with RAID will call us at some point in the first year to report a degraded RAID array or problem directly resulting from their RAID configuration. Granted, a failed RAID1 array does not mean data loss, but it certainly means a long, frustrating hassle.
His judgement is that most customers are happier with regular backups and have way fewer problems. I’d amend that to better off with an automated offsite backup service like
Carbonite or
Mozy which are both set and forget.
What RAID doesn’t protect you from
Jon also notes that backups offer protection that RAID doesn’t. Specifically, RAID can’t help you with:
1. Accidental deletion or user error
2. Viruses or malware
3. Theft or catastrophic damage
4. Data corruption due to other failed hardware or power loss
Where will Jon recommend RAID?
For a desktop machine he allows that striping (RAID 0) may make sense if you know you are I/O bound in things like video editing. He also recommends that if you do go the RAID route, buy a quality RAID controller. He’s found that Windows-based RAID software is prone to problems.
Jon isn’t talking about server RAID
But I will. If smart engineers did a clean-sheet storage design today, they wouldn’t come up with today’s RAID systems. That, however, is a topic for another time.
Why home RAID won’t fly
Fellow ZDnet blogger George Ou posted this morning on
Why dumb-downed no-RAID storage is bad for consumers. With all due respect, George couldn’t be more wrong. RAID doesn’t solve the home storage problem and its usability stinks.
The vendors who are backing off from selling or promoting RAID in the home are doing the right thing. Consumers don’t want RAID, they want to protect their data.
“Dumbed-downed” vs “it just works”
RAID, or any technology, is just a tool. Sometimes it is the right tool, sometimes it isn’t. RAID isn’t the right tool for consumers because it doesn’t meet consumer needs.
Well, RAID meets one consumer requirement: it has a catchy name.
RAID’s #1 problem: it doesn’t work
Consumers don’t want to lose their data. RAID doesn’t solve that problem: it is easy to lose data on a RAID array. It happens every day. Otherwise perfectly competent sysadmins and techs pull the wrong drive. They copy from the empty disk to the data disk. Silent data corruption hoses files and directories. Data disappears, never to return.
The very best that RAID can promise is that it protects your data better than a single disk. But any RAID system is still logically a disk and physically a group of disks. Therefore it will suffer all the ills of disks. A home environment, with crummy power, old cables and dirty air, is a stress test for disks.
So if you sell home RAID promising to protect people’s data, get ready for a world of hurt. “Class-action lawsuit” ring any bells?
RAID’s #2 problem: ease of use
Is the iPod/iTunes combination “dumbed-down” or “smartened-up?” The latter, of course. Even with five years to copy them, reviewers like Walt Mossberg say that no one else has the ease of use of iTunes.
Ease of use means something a little different in the world of RAID. RAID ease of use has to tackle two problems: setup and break/fix.
Setup is easy if you don’t mention RAID
Consumers have zero interest in RAID levels, and there is no way anyone can make RAID interesting enough that they’ll want to learn. So setting up a consumer RAID box means doing it for them.
Maybe that’s “dumbing-down” but I think it’s smart. And if you’re not going to let people set their RAID level, why mention RAID in the first place? Even smarter.
Break/fix is the hairy part
RAID’s other usability problem is a little different: it breaks ugly. You have to pull out a disk. You have to pull out the right disk. You have to put in a new disk. You have to wait hours after you replace the disk for the system to get back to normal.
Error-prone and impatient consumers are going to screw these up. Often. When they do the vendor will be blamed. And rightly so.
So what does work in home data protection?
I want to say one word to you. Just one word.
Backup.
Home users want to protect their data. RAID won’t do that. Backup will. It is that simple.
Now, there are a lot of possible variations on backup. Backup to disk. Backup to optical. Backup to Carbonite, Mozy or another on-line service.
One of the reasons that iTunes is successful is that backup is the data protection strategy. You store everything on your computer and sync to your iPod. Two copies, all the time.
The Storage Bits take
I like what Data Robotics is trying to do with Drobo. As I wrote two months ago:
I’ll be surprised if it isn’t a success, especially as volume ramps and distribution widens. Non-geeks don’t want to manage storage or drives. They just want to store their stuff, safely. Drobo gets that and makes it easy. It is the iPod of mass storage.
It is still an open question whether Drobo actually delivers on the promises. But at least they are making the right promises.
Update: all the good comments helped me sharpen my thinking about home RAID. If you want v2.0 it is over on StorageMojo. Living in a small town in the mountains of northern Arizona, I actually interact daily with the target market for home RAID. That’s why I know it won’t fly.
wie schrecklich unvorhersehbar diese doch seien usw usw.
) werden, weil sich nur etwa 1% damit wirklich auskennt. Außerdem verbessern sich nicht alle erformancerelevanten Parameter bei RAID, einige leiden, es kommt daher auch auf den Anwendungsfall an. Weitere Punkte kannst Du auch in der Suche im Forum finden.
