RAID setup for my audio based Mac Pro

[mawsir84]

Hey everyone -

This is my first post on this great forum, although I have referred to it many times for quality info. I am a QA engineer for Cakewalk music, so I plan on giving back to the community down the line with audio topics. Here we go:

I have a Mac Pro I got from work and want to set it up right for problem free, redundant operations because I do my personal and work related projects on it and the data is irreplaceable. Here is what I have and how I was planning on doing the setup. Any feedback would be great, because this is my first RAID setup and wanna get it right:

Disk 1 = 370GB (OSX and Bootcamp)
Disk 2 = 1 TB (Media, samples, project files, etc)
Disk 3 = 1 TB (RAID 1 paired with Disc 2)
Disc 4 = 1 TB (OS Images and Time machine backup for Disc 1)
External HD = 1 TB (Raid 1 Paired with Disc 4)

*All RAID will be done through Disc utility

My specific concerns:
1. Will having Disc 2 and 3 as a RAID 1 Pair decrease the disc performance? I will be using disc 2 to stream audio samples into my softsynths and was wondering what kinda of negative impact RAID 1 has on streaming.

2. Can you setup an external HD as a RAID 1 pair with an internal drive? I will not be streaming any audio off Disc 4 so performance is not an issue. It would just be nice to have a redundant backup of the drive with all my images and Time machine data.

Any input would be great! Thanks in advance.

 

[garybUK]

Raid 1 should have little or no performance impact maybe a little on write performance but you should be good to go here. Raid between a internal and external disk isn't a great option but is do-able. As long as it's only Raid 1, but performance may decrease depending on the connection speed.

An alternative is to make the three internal 1tb drives Raid 5, this will use one drive as parity and have 2 drives as 2TB, if one drive fails you can replace it with no data loss. But if two drives go down your snookered! Raid 5 does give performance increases as well.

I'd also mention with any raid system its recommended to have a UPS, even a cheap one to purely shut your machine down cleanly.

 

[khollister]

First off, OS X Disk Utility can only do RAID 0, 1 or JBOD. It cannot do RAID 5 or 6.

Before I suggest anything specific, how large are your sample libraries and project folders? Are you MIDI only, or also recording live audio? What host are you using (I thought Sonar was Windows only)?

A few general thoughts:
* Larger drives are usually faster due to data density on the platters. Current 2 TB drives are almost always faster than 1 TB or smaller.
* Software (apps/OS), sample libs and audio/MIDI recording should ideally be on separate drives (not just partition volumes, but physical drives). This eliminates drive head contention.
* Audio recording/playback is not particularly high bandwidth, so RAID 0 (stripping) doesn't buy you anything there except reduced reliability - lose one drive, lose the set. Since all the drives have to operate, you have a higher chance of failure than with a single drive.
* In your scenario, the only thing I would consider doing a stripe set for are the sample libraries. Since these are pretty static (unless you purchase new ones or update them), RAID 0 isn't much of a risk providing you have backups. You don't need hourly backups of this stuff since it doesn't change frequently.
* Backup strategy should cover 3 things - accidental corruption (SW install or human error), drive failure & disasters (fire/theft/flood/direct lightning hit).
* Time Machine is good for the first two, especially on things that are either small (OS) or change frequently.
* You need drive clones (via CCC) that you can store away from the computer and preferably off-site for the third.
* Static data you keep on RAID 0 (sample libs) can either be protected from drive failure by TM or the clone sets.
* Short-stroking drives can be much faster. Data stored in the outer portion of the platters is read much quicker than that in the inner sections. Therefore you want to keep drives half-filled or less and/or use partitions to force performance critical stuff into high-speed portions of the drive. Partitions you create are placed on the drive in the order they are created, outside to inside.

So you probably want something like a RAID 0 stripe set across 2 small volumes (one partition on each of your 2 fastest data drives at the top of the partition map) for samples, with the remainder of the drives used individually for other data that is less speed-dependant.

Since Time Machine backups are not bootable, and are more effort to use to restore an failed drive (as opposed to restoring a few deleted files), I feel using a second drive to mirror a TM volume rather than creating a drive clone which is bootable and quicker to restore an entire drive/volume, is a bad idea.

So, specifics aside, I would be thinking about something like:
Drive 1 - OS+apps
Drive 2/partition 1 - member of stripe set for sample lib
Drive 2/partition 2 - Home directory/data
Drive 3/partition 1 - member of stripe set for sample lib
Drive 3/partition 2 - more data storage - maybe dedicate to audio recording?
Drive 4 - Time Machine (needs to be 2x what you are backing up)

External - clone(s) I use a bare drive dock with multiple naked drives that I store in plastic boxes.

Your other option is to get 4 identical 2 TB drives and go RAID 10 (2 RAID 1 mirror sets that are then striped via RAID 0). This gets you the speed of stripping without the reliability hit. You would then have an external backup solution - more drives, more money.

 

[mawsir84]

thank guys

My sample libraries are for the moment around 500GB, but that is sure to keep increasing. I do both Midi based production (soft synths, etc) and record live audio to disk. I use Logic studio primarily (yes, sonar is win only, but I am the QA manager for our instruments, many of which are Cross platform- I also have a windows box in my setup)

I am digging your suggested setup and you def gave me some info i wasnt aware of, some questions though:

1. What is backing up Disc 2 and 3 if they fail? (are you saying just make monthly disc images of them and store them on an external?)

2. If Disc 2 and 3 are a striped set, if one fails it takes the other with it right?

3. Would carbon copy clone be backing up all 4 drives? If so, that would be a rather large investment to get 4 more TB of data.

So based on your suggestion, maybe this would be better:


Disc 1: OS and Apps
Disc 2: P1 - Sample library (member of striped set)
P2 - Itunes library, photos, non performance based media
Disc 3: P1 - Sample library (member of striped set)
P2 - Project Files locations to stream recorded audio to and from
Disc 4: Time machine backup of Disc 1

External: Backup location for CCC use.

 

[khollister]

The non-striped partitions on Disk 2 & 3 would be backed up by Time Machine and/or the clone backups (TM for the stuff that is active, clones would pick up the stuff that is mostly read-only). The partitions that make up the stripe set both have to work for the data to be accessible, but since that is read-only (sample libs), if you lost that, you could just restore it from the last clone once the HW is fixed. Your project files on the other partitions would be likely backed up by both TM as well as the clone sets.

Now that I read this again, there is one flaw in what I proposed - your audio recording will be streaming to the same physical drive(s) as you are streaming samples from. You really should get the audio recording (and probably the MIDI tracks) off the drives being used to stream the samples to your sampler instruments. While it is no problem putting other stuff on there that you are not simultaneously using while in Logic, you should keep audio and sound libs separate.

One option is to move the boot drive to the 2nd optical bay and add another HDD

 

[khollister]

And drives are cheap (2 TB for $100 - you don't need WD Caviar Blacks for backups). It's like insurance - nobody like paying for insurance until their house burns to the ground and you wonder why you didn't have more.

 

[ChrisA]

About backup:

#1 RAID is not a backup plan. Some RAID types are less reliable then a single disk. "Stripes" are that way. If either disk fails you loose everything on both drives. You double the chance of loss . You use it because either you need a larger disk then you can buy right now or you need a faster disk. A Mirror can be more reliable But you loose performance for writes and double the total cost per gigabyte.

#2 If you care about the data and don't want to loose it there are some rules you must follow...

a) All data must exist on at least three different physical meadia at all times (including durring a backup operation)

b) All data must exist in at least two different gregrpahical locations (different buildings) at all times, Even while being trasported.

Ideally you want a system that insure that you will always have two copies of data after any kind of disaster, such as a software glitch, operator error, disk crash, fire, theft.

The above are the bare minimum. What this means is that you have two external backup disks and one of them is kept far away.

A simple plan is to use Apple's "Time Machine". Keep a TM disk connected to your computer and it will automaticaly do a backup every hour. This disk needs to be at least 1.5X larger than all the data you have on al your drives. If yu have a lot then this "drive" may need to be a RAID. TM will make sure y ou always have two copies of your data.

I have a fire safe at home. In addition to using TM, periodically I make clone of my data disks and place the clone in the safe. Then the disk that was in safe, that has the older cloned image on it goes to my office at work and then I bring home the disk I had there and use it for the next cycle. So I rotate a set of images and also use TM.

Youuhave to think about hw people loose data. A common way is to loose the disk to theft or fire. It should be clear that RAID and TM don't help with theft or fire loss. Lightening striking a utilty pole within about a half mile of the house can take out all of your equipment that was plugged in, even if turned off. So you don't want you backups on an active drive, afie safe works well. And then

Disk drives are so cheap now. 2TB for $100. Is your data worth $1,000 or $100K? If so then invest in four of five 2TB drives for a rotating backup system

those "clone" programs are not very good ways to make backups. The reason is a "classic" scenario. Say yu have the perfect film script you've worked on for years. But one day the file get corrupted when you do the File->Save. Welll that's OK as y u have a "clone" of your ddisk you make the day before. Well OK until you over right that disk when you over write it with today's image. Now you've just killed your only good copy of the file.

Clones are OK if yu have a stack of drives and you rotate them and only write over old data that is weeks old. Time Machinne is good in that it never overwrites any but the oldest data.


No one does this. (Well except many a few professional photographers and others who really d depend on their data for a living.) So I predict that in 100 years there will be almost no 100 year old photos. Unless you folow a plan something like the above your data will not last. Something, a fire a dumb mistake, a software crash,... will take it out.

 

[KeithPratt]

Some RAID types are less reliable then a single disk. "Stripes" are that way. If either disk fails you loose everything on both drives. You double the chance of loss .

You don't double the chance of loss. You just lose twice as much when one disk fails. There are other kinds of faults that can ruin an array, however.

I look at RAID as being good for two things: one, increased bandwidth, and two, minimising downtime. Audio rarely requires the former, but the latter is useful in almost any situation. But I'm not sure you need RAID...

OP, are the striping and partitions necessary? Would the following not be enough?

Disk 1: OS and project files
Disk 2: audio and sample libraries
Disk 3: clone of Disk 1
Disk 4: clone of Disk 2
And an off-site backup of the lot

You could be more cautious than this, and if you're of that disposition it'll probably make you feel more at ease, but what is life without a little risk?