Some RAID questions
by Alex Elkins
on
Oct 6, 2008 at 3:41:47 pm
I've been doing a lot of research into RAID systems recently as I'm soon to purchase a new edit suite. There are a few questions that I still have, that hopefully someone can answer...
I want to have around 8TB or more of external storage set up as RAID 5, capable of handling 10bit HD. Most of what I currently do is captured as ProRes, but I'd like the option there for 10bit HD.
From what I've read on this forum the Maxx Digital and CalDigit systems seem popular. I've also come across a company called ProAvio - does anyone know anything about them? 10TB for £4000 (£££ not $$$) seems in keeping with the competition.
Would any of these units support 2k work?
What I'm slightly confused about is the difference between hardware and software RAIDs. I understand that hardware is more stable and doesn't strain the CPU, is this correct? Also I'm lead to believe that it isn't possible to create a software RAID 5 anyway. So hardware is definitely the way I'll need to go.
With that in mind, how would I go about setting up a hardware RAID? For instance, does using a RocketRaid 3522 card and an 8TB CalDigit RAID = hardware RAID, or am I missing something?
I'm aware that it's possible to have the hardware actually onboard the RAID, but those systems are more than I need or can afford.
Regarding internal storage, I'm thinking about one drive for OS and software and then three 1TB drives striped. These drives would be used primarily for archiving, paperwork and maybe some music and personal stuff (as I work from home) but I'd like the option there for use as media storage as a last resort, hence the RAID configuration. Will having a RAID controller in use with the external RAID allow me to hardware configure the internal RAID? If not, would I be unwise to have these drives as a software RAID 0 (bearing in mind what I've said I'll be using it for)?
Any advice and recommendations are greatly appreciated.
Re: Some RAID questions by Russell Lasson on Oct 6, 2008 at 5:33:52 pm
[Alex Elkins]"Would any of these units support 2k work? "
Yes. As long as you can safely get over 300MB/sec, then you'll be able to do 2k. Most of the systems you're talking about get closer to 500 or 600MB/sec.
RAID 5 is usually hardware based. I think you'll really like the 8 drive RAID 5 setup.
-Russ
Russell Lasson
Ridgeline Digital Cinema Mastering
Universal Post
Salt Lake City, UT
Re: Some RAID questions by Shane Ross on Oct 6, 2008 at 6:46:10 pm
NO need to stripe the internal drives....they are pretty fast on their own. Internal SATA can get 120MB/s...plenty fast for most codecs, except Uncompressed HD. Plus if you raided them all together RAID 0, if you lost a drive, then you lose all that information....across ALL drives. And since that would be a SOFTWARE Raid, if your OS crashes in a bad way, then the information is lost as well. But you can look into a hardware raid controller for that, like the CalDigit or Apple one (CalDigit is half the price of the Apple one...and you can install it yourself). But if you are going to have external RAID storage, having TWO controllers might be overkill.
Re: Some RAID questions by Alex Elkins on Oct 6, 2008 at 6:59:19 pm
Thanks a lot Shane, you've saved me a bit of cash there, and more importantly the potential for losing lots of data. Given the usage I'd have for the internal storage I'll happily settle for just the OS drive and then a further 1TB SATA then.
Any recommendations on the actual drives to choose - I can't go wrong with Hitachi, right?
Re: Some RAID questions by Bob Flood on Oct 6, 2008 at 9:39:00 pm
Alex
I would add a third internal drive and use it as a "mirror" of your system drive, and any valuable data on the second drive.
this is waht i do
My system drive, Macintosh HD, Has the OS, all the programs, and their prefernces and so on
My second drive, which i affectionatly call "Internal Secondary Drive"
holds all my project data, like FCP projects, DVD projects, autosave vault, waveforms and thumbnails, etc. I also use it for exports, dvd media, some sound files like music and sfx, and the like.
I have a third drive which i call "backup". I use Retrospect to copy ALL the system drive over to it once a day, as well as the Project info off my secondary drive. If either my primary or secondary quit, i am kinda covered. (i am working on "Ghosting" my system drive so i can get up and running faster)
BTW all of this is in addition to, but independent of, an e-sata raid that holds all the video.
Re: Some RAID questions by Alex Elkins on Oct 7, 2008 at 7:33:13 am
Thanks for all the feedback, Bob.
[Bob Flood]"I would add a third internal drive and use it as a "mirror" of your system drive, and any valuable data on the second drive." That's a sensible idea, thanks.
[Bob Flood]"My second drive, which i affectionatly call "Internal Secondary Drive"
holds all my project data, like FCP projects, DVD projects, autosave vault, waveforms and thumbnails, etc. I also use it for exports, dvd media, some sound files like music and sfx, and the like." This is actually what I tend to do, but I've often wondered whether or not you should keep your project files etc on the same drive as the media. Is that generally considered a bad idea? If so, why?
[Bob Flood]"i am working on "Ghosting" my system drive so i can get up and running faster" What does ghosting a system drive mean? Why does not doing it mean you're up and running more slowly?
Re: Some RAID questions by Bob flood on Oct 7, 2008 at 1:52:10 pm
Alex
I've often wondered whether or not you should keep your project files etc on the same drive as the media. Is that generally considered a bad idea? If so, why
I am not sure if it matters anymore as far as throughput goes, but one thing for certain, if your media drives go down, and your project is on there too, you are Hosed.
that being said, i do some work for a company that gives every project its own half Tb or 1 Tb drive, and they keep everything on it, project, media, renders.
What does ghosting a system drive mean? Why does not doing it mean you're up and running more slowly?
Ghosting refers to a program by norton/symantec called, appropriately enough, Ghost. it makes a true, bootable clone of the system drive that you can simply slide in, or restart with, and you are up
and running. However, i think thats all you can do ie you can only clone your system drive, and cant back up any other drive on there, but as i am doing research on this, i caould be mistaken
Re: Some RAID questions by Alex Elkins on Oct 7, 2008 at 4:29:36 pm
[Bob flood]"it makes a true, bootable clone of the system drive that you can simply slide in, or restart with, and you are up
and running." So kind of like you tell it to copy the contents of your boot drive when it's working ok in case there's a failure five minutes later? A bit like Preference Manager??
So presumably the benefit of doing that is you don't need to buy a backup internal drive, is that right?
Re: Some RAID questions by Bob Flood on Oct 6, 2008 at 9:27:59 pm
Shane
you said "And since that would be a SOFTWARE Raid, if your OS crashes in a bad way, then the information is lost as well"
My understanding was that, unlike PC's. the Mac OS actually wrote the stripe information to the raid 0 drives, such that if you did lose your system drive, or had to wipe it, or had to reinstall system from scratch, you would retain the stripe info, and once you got your system back, the drives would show up as a raid o stripeset with all the data intact.
BUT, you still cant do raid 5, and as its raid 0, you still run a risk of losing all the data if one drive fails.
Re: Some RAID questions by Shane Ross on Oct 6, 2008 at 9:48:52 pm
SInce I am not the DEEP technical guy, I go off what technical guys tell me. And I have heard from more than one source that software Raids are vulnerable if the OS crashes. They might not fail, but there is a chance they will. That is what I have been told.
Re: Some RAID questions by Anne Mills on Oct 8, 2008 at 12:08:59 am
Hello,
I just want to help out and further clarify the difference between hard ware and software RAIDs because the performance level does differ between the two.
When ever you are having doubts about whether it is a hardware RAID ask the vendor two questions Does it have and independent CPU and Does it have an independent cache memory? If the answer is yes to both questions you know you are dealing with a hardware RAID.
Hardware RAIDs have a dedicated CPU this frees up the host system CPU resources to make applications more efficient. Software RAID makes the host work harder because you’re using the host CPU
If it is RAID 5, it does not necessarily mean it is a hardware RAID, there are products that support RAID 5 and are software RAIDs.
Re: Some RAID questions by Alex Elkins on Oct 8, 2008 at 3:26:46 pm
Thanks Anne,
Could you clarify for me then whether any or all of the systems I mentioned in my original post are indeed hardware RAIDS? I don't know how familiar you may be with any of them, but if you can shed some light that'd be great.
Re: Some RAID questions by Anne Mills on Oct 8, 2008 at 11:59:52 pm
Alex
I believe both the Evo2 and CalDigit are hardware RAIDs. I just want to reiterate that RAID 5 doesn’t equal a hardware RAID. I do recommend questioning the vendor just to see how competent they are in their product knowledge. It also helps to see who you’re dealing with and how much they know about video editing so you can get the proper support.
