A question for those with some technical knowlege/experience with RAID arrays:
So i'm upgrading the storage capacity on the ol' G5, and since the factory drive ports are full, i'm thinking that the best way to accommodate all those huge sample libraries i'll want to stream from disk in the near future is to put in the additional triple-bay internal rack and add 2 or 3 matched drives as a striped RAID array.
So here are the options i'm considering:
A) Two Western Digital Caviar 320GB 7200rpm 3GB/sec sustained transfer rate, for ~$300,
B) Three Western Digital Caviar 250GB 7200rpm 1.5GB/sec sustained transfer rate, for ~$210
My reasoning process so far has been something like:
- The two larger drives with a 3GB/sec transfer rate (option A) cost a bit more, but the advantages would be a higher theoretical data transfer rate (6GB/sec) and one fewer drive to make noise, suck power, or break down;
- On the other hand, it may be that three 1.5GB/sec drives (option B), would in reality provide similar performance, or at least performance in excess of what i would ever need (4.5GB/sec) given that i'm streaming audio notes and not HD video, the one additional drive won't make that big a difference in noise pollution or power consumption, the total storage capacity is larger, the 250GB format might be more durable than the higher capacity format, and it costs less.
> For audio, I would not do RAID on a Mac. The conventional wisdom is that audio uses many small streams of data, unlike video, which uses one large stream.
Sorry to go against your idea but :
If on one song you have a lot of strings and on another a lot of brass how are you going to organise your libs !
What is a Raid, you spread your files at the block level (64 or 128 kb)
More disk you have faster the RAID will be.
Splitting you libs on multiple drives is what the RAID software is doing automatically for you !
I use a RAID 0 to put my QLSO PLATINUM, before I had this Raid I could not play my test song on a G5 2x2 3.5 gb (this song was just playing with Logic/EXS/VSL on a G4 533 MP !!!)
Concerning Jloeb :
> 1) If i'm out of warranty (1yr), have i already lost Apple care support anyway?
- Apple care if you got it is 3 years, also if you put too many device in the G5 you may ruin the power supply
> 2) An external RAID box won't be equally noisy?
it depends of the box
> Do i need to worry about speed so much if i'm not working with any video, just a lot of streamed instruments?
- What lib are you going to use ?
The best organization are :
Your system must be on a separate disk. (not on the Raid)
1) The ultimate :
A Raid 5 to put your audio files
+ A Raid 0 to put your libs
+ A separate disk or volume to put your swap files
2) The best : A Raid 0 to put your libs
A separate disk to put your audio files
> Can you recommend a good external box?
- You have to check that the noise pressure is under 37 dBA
You may need an extra power supply
Also it depends of your budget
I have put my 6 disk on a metallic tray in my Omnidesk from Omnirax and I have add 2 small fans, this is the cheapest, I have 7°C more that the external temperature
What you should do is buy the box near where you live so if it is too noisy you can take it back, because a know at least one manufacturer that has announced me 35.55 dBA before I bought there box I got it and I have mesure 53 dBA.
I cannot give you the name right now because I am trying to get my money back and I just gave then a 2 weeks notice before putting the information on all the forums
So it seems like the principle that's being argued over could be articulated as follows:
There is a maximum fragmentation level of the target read-file beyond which using a RAID will not gain you any advantage, and can in fact hurt performance due to the increased total number of seek events.
This sounds intuitive to me, but i don't know enough about RAID technology to know whether it's actually true or not. Two pieces of empirical evidence are:
- there certainly are people out there who claim to be using it for digital audio, but
- digidesign certainly does not support its use, and this is a technology that's been around for a long time now so there is almost certainly a reason for that.
Hmm. So from my own Googling around, i have come up with a couple of points from storagereview.net:
"RAID 0 has no positive effect on seek times. It can induce additional seeking delays."
"In other words, sequential transfers already complete so quickly that they have in effect written themselves out of the performance equation. Doubling the performance of a factor that exerts such a small effect nets a small improvement... as one should expect.
This is something I've long considered to be one of the dominate reasons behind the poor performance improvement offered by striping. It's great to have exact numbers to quantify it."
A Groove Machine presentation on designing DAWs says:
"What makes a great Digital Audio Workstation?
Hard Drive Speed/Interface Type-
• So why can’t my current music PC handle this many tracks?
1. Fragmented hard drives – defrag as often as possible
2. Speed ratings are interface maximums, not actual throughputs capability
of drives- RAID Arrays solve this."
In this presentation, the purpose of the RAID arrays seems to be for *recording* tracks, not playback of streamed instruments. This makes more sense, as you're reading/writing a relatively small number of large-block audio files.
Can anyone speak from expert experience on this issue?