MBP, Apple software RAID 1 mirror setup, startup boot volume PROBLEMS

Question

Level 1

0 points

MBP, Apple software RAID 1 mirror setup, startup boot volume PROBLEMS

Hi

Looking to do following setup:

* MBP 160G internal HDD ->
1) HFS+ Volume: System (want RAID 1) 100G
2) HFS+ Volume: Public (regular) 60G

* External 100G 2.5 HDD USB2 box ->
1) RAID 1 spare for System volume

My experience after working on it for about 18 hours straight is there are some seriously wack problems with OS X being able to boot from such a setup.

At first I ASR everything to USB drive, I kill the 160G volume, create only the 100G RAID volume (thought I could add more at any time and didnt know I could just shrink the original), restored from USB2, booted off USB2 to put real system disk offline.

Load Disk Utility, drag System volume around, click Enable in RAID tab and it showed up everywhere it needed to. I was even able to boot from the internal volume while it was RAID 1-d. Yippee, methinks, now I just add the Public non-RAID volume and everything is dandy.

Yeah, right.

First of all, you apparently cannot add a partition, when you already have RAID mirror setup on the first partition. What the **** is that all about? They cant figure out how to do that?

So I destroy the internal RAID, 100G System volume turns back into normal, I add the 60G Public JHFS+ partition, re-enable RAID on System 100G, everything looks normal. Yippee, methinks, now I just reboot off the RAID volume and all is good.

Yeah, right.

RAID 1 System volume simply does not show up as a bootable device. I just stare at the screen in amazement - can Apple tech really be THIS weak? I mean I have a more complicated setup running in Linux including MD, LVM2 and LUKS encryption for a few years now, and I did not even have topay out of my arse for that.

Boot off USB, disable RAID on System, remove Public partition, enable RAID on System, reboot - again we can boot off the RAID volume. I stare at the screen in amazement.

Boot off USB, disable RAID on System, put Public partition back, enable RAID on System, reboot - nope, it cannot find a startup volume.

W... T... F.

Google datacenters must be smoking of all the Googling I did to find out what the heck kind of restrictions exist on this. The information is SO scattered and incomplete and random, it has been impossible for me to deduce conclusively whether this INCREDIBLY SIMPLISTIC SCENARIO can actually exist on Apple technology. Ive gone through loads of information describing all sorts of mirror RAID scenarios, all sorts of problems with having more than one partition/volume on the RAID disk, the fact that the setup looks like it needs a separate Apple_Boot partition to boot off of, EFI problems with RAID, SmartRAID, etc, etc. But NOTHING that describes to the point what I want to do.

QUESTION: Can anyone tell me, am I supposed to be able to put my BOOTABLE "System" Volume into RAID 1 and also have ANY other partition on ONE DISK?

Trial and error on my MBP shows EFI seems to cough blood as soon as you put anything else on the disk aside from JUST the single RAID volume. Which frankly would be WEAK as **** and more like up Microsoftish crap alley.

MBP 2.4, Mac OS X (10.5.4)

Posted on Jul 16, 2008 2:46 AM

Reply

Answer 1

Kappy

Level 10

361,741 points

Jul 16, 2008 3:04 AM in response to slexus

MBP 160G internal HDD ->
1) HFS+ Volume: System (want RAID 1) 100G
2) HFS+ Volume: Public (regular) 60G

External 100G 2.5 HDD USB2 box ->
1) RAID 1 spare for System volume
My experience after working on it for about 18 hours straight is there are some seriously wack >problems with OS X being able to boot from such a setup.

In god's name why? What is the point of this exercise? Do you not understand that one should never use a RAID as a startup volume? That it is foolish to create a RAID with an internal and external drive on a laptop since the RAID will be destroyed when the external drive is unplugged? Are you really trying to create a RAID using two partitions on the same drive? And, that you don't seem to know much about RAIDs?

RAIDs are for large enterprises not people with laptop computers. They certainly should never be used for startup volumes, and they aren't the best choice for one's main backup.

RAID Basics

For basic definitions and discussion of what a RAID is and the different types of RAIDs see RAIDs. Additional discussions plus advantages and disadvantages of RAIDs and different RAID arrays see:

RAID Tutorial;
RAID Array and Server: Hardware and Service Comparison>.

Hardware or Software RAID?

RAID Hardware Vs RAID Software - What is your best option?

RAID is a method of combining multiple disk drives into a single entity in order to improve the overall performance and reliability of your system. The different options for combining the disks are referred to as RAID levels. There are several different levels of RAID available depending on the needs of your system. One of the options available to you is whether you should use a Hardware RAID solution or a Software RAID solution.

RAID Hardware is always a disk controller to which you can cable up the disk drives. RAID Software is a set of kernel modules coupled together with management utilities that implement RAID in Software and require no additional hardware.

Pros and cons

Software RAID is more flexible than Hardware RAID. Software RAID is also considerably less expensive. On the other hand, a Software RAID system requires more CPU cycles and power to run well than a comparable Hardware RAID System. Also, because Software RAID operates on a partition by partition basis where a number of individual disk partitions are grouped together as opposed to Hardware RAID systems which generally group together entire disk drives, Software RAID tends be slightly more complicated to run. This is because it has more available configurations and options. An added benefit to the slightly more expensive Hardware RAID solution is that many Hardware RAID systems incorporate features that are specialized for optimizing the performance of your system.

For more detailed information on the differences between Software RAID and Hardware RAID you may want to read: Hardware RAID vs. Software RAID: Which Implementation is Best for my Application?

Reply

Answer 2

slexus Author

Level 1

0 points

Jul 16, 2008 3:37 AM in response to Kappy

First, I definitely appreciate the effort put into responding. Helps me think and clarify the problem further.

Unfortunately your efforts are quite misdirected. I did not ask for WHY advice, I have so many WHY reasons, it is not very effective to discuss them here. At the ultimate baseline level, some relate to "gain knowledge whether this can be done, related problems etc", something that every professional needs to do here and there.

But lets dissect the response anyway, because in my view, you are quite shortsighted if those below are your professional level views and analysis about this probably somewhat expands my knowledge.

In god's name why? What is the point of this exercise? Do you not understand that one should never use a RAID as a startup volume?

You cannot be serious? I'm certain basic Googling gives you loads of writeups where it is shown and thoroughly argued WHY it is among best practices to RAID your server startup volumes NOT FOR PRIMARY BACKUP but FOR MINIMUM DOWNTIME, hence the "redundant".

That it is foolish to create a RAID with an internal and external drive on a laptop since the RAID will be destroyed when the external drive is unplugged?

This falls into the WHY category as well, it is my fault not writing up that the reader should assume, that I am already aware of majority of issues, such as unplugging the USB drive in the middle of sync - it's something elementary that I simply will not be doing in my process execution.

Are you really trying to create a RAID using two partitions on the same drive?

----> NO <---- I would really appreciate it if you could show where my written English (2nd language) in the original post is so bad, that one with any serious professional knowledge could interpret that mirroring partitions on the same drive is my goal.

<div class="jive-quote">And, that you don't seem to know much about RAIDs?

That remains to be seen. I guess my previously described happily operating Linux setup proves to myself that I do know enough to have it working they way it is supposed to in a way more complicated scenario than what I try to do on this Apple laptop.

RAIDs are for large enterprises not people with laptop computers.

This would be the weakest point in your argument. Let's not even get into "RAIDs are for large enterprises" since arguing about this is a complete waste of everyone's time. Perhaps lets just keep in mind that these laptops are more powerful than most large enterprises had their top servers not so many years ago.

They certainly should never be used for startup volumes, and they aren't the best choice for one's main backup.

I have no idea where you get this "RAID is not for startup volumes" claim. Just do your computers/servers your way and I'll do mine my way.

RAID Basics

For basic definitions and discussion of what a RAID is and the different types of RAIDs see RAIDs. Additional discussions plus advantages and disadvantages of RAIDs and different RAID arrays see:

Having already said I have my own Linux server running for a few years already complete with Linux MD, LVM2 and LUKS encryption integration, I thought that would eliminate the need for anyone to start pasting URL-s about RAID Basics. Guess I thought wrong.

My original question still stands. Thanks for the reply.

Reply