Using external hard drives + RAID with iMac

[iMikeT]

When I get my iMac I am going to be getting this external hard drive enclosure. The enclosure is capable of taking two bare drives and using hardware RAID. I will be using the enclosure to store my data.

Now my question is if I decide not to go with the hardware RAID option and use Disk Utility on an i7 iMac for software RAID, how well will the iMac handle data transfers along with normal processes simultaneously? Will going the software route hinder other processes for example, Photoshop? Also, does anyone here have a RAID setup with an iMac or any other Mac and what is your experience like?

 

[iMikeT]

Anyone have any ideas?

 

[HobeSoundDarryl]

Use the hardware raid. No benefit to using software raid.

I have a 2-drive raid hooked to my iMac (firewire 800). For the most part, it works great. Very fast- often hard to notice that data on it is external vs. the internal 2TB HDD. I store a fair amount of big data files there (including multi-gig movie files). I even store raw HD video shot with the camcorder to be processed with iMovie. Again, speed seems great.

The ONE frustration I have is that sometimes it goes to sleep when my iMac sleeps (every night late) and doesn't wake up with the iMac wakes. This doesn't happen every night- just sometimes. All it takes is unplugging the external, waiting a few seconds, and plugging it back in... but it would be nice if it would sleep & wake right in sync with the iMac (in other words, EVERY TIME). I've noticed the same effect with some USB devices too, which makes me wonder if there is some bug in the iMac hardware relative to sleep/wake cycles... or if the bug is instead in various external devices (both firewire & USB).

 

[RaceTripper]

I just ordered the exact same enclosure, but plan to use it for a software RAID 1 via disk utility. I will probably put a pair of matched 2 TB drives in it, although I haven't decided on any (maybe WD Caviar Black?).

 

[iMikeT]

Use the hardware raid. No benefit to using software raid.

I just read the specs again on the enclosure that I'm planning on getting and it doesn't seem to support RAID 1 through the hardware. So it seems that I'm not going to benefit from using hardware RAID.

Another question for you though, why can't you benefit from software RAID, or is it just how you yourself have your system set up?

I have a 2-drive raid hooked to my iMac (firewire 800). For the most part, it works great. Very fast- often hard to notice that data on it is external vs. the internal 2TB HDD. I store a fair amount of big data files there (including multi-gig movie files). I even store raw HD video shot with the camcorder to be processed with iMovie. Again, speed seems great.

I'm planning to have a similar set up, that is to use the external drives for raw data and all my media files. Transfer speed and between the iMac and the drives and overall read/write performance speed will not be an issue for me as much as redundancy and reliability that my data is on two separate but mirrored drives.

But going back to my original question... Do you see any performance issues on the iMac itself during data transfers while you're in the middle of other tasks?

 

[iMikeT]

I just ordered the exact same enclosure, but plan to use it for a software RAID 1 via disk utility. I will probably put a pair of matched 2 TB drives in it, although I haven't decided on any (maybe WD Caviar Black?).

It seems that you and I are going to have a similar setup out of the gate. Like I said in my last post, I took a look at the specs of the enclosure again and it doesn't support RAID 1 from the hardware.

I'm probably going to order the same WD hard drives that you are but I'm really tempted to step it up and order the 3 TB drives.

Since you're going to be using software RAID with Disk Utility, are you expecting to see any performance issues on the iMac itself while you're in the middle of data transfers and doing other tasks?

 

[RaceTripper]

Use the hardware raid. No benefit to using software raid.

I've been talking to a friend (who also works for me) and has a lot of expertise on systems (he's our guy when we need to do Linux servers, etc). He always uses software RAID, because he says he's been burned by hardware RAID.

A controller adds another point of failure, and if it fails and gets replaced, there is no guarantee it will revive the old RAID as it was, in which case it has to be reconfigured with consequent data loss. RAID controllers are proprietary and if they aren't exactly the same, can be a problem as a replacement (even for identical hardware that has maybe just different firmware). And he is not the only one I have heard that from.

So if you look at it that way, there is a benefit to software RAID.

 

[RaceTripper]

It seems that you and I are going to have a similar setup out of the gate. Like I said in my last post, I took a look at the specs of the enclosure again and it doesn't support RAID 1 from the hardware.

I'm probably going to order the same WD hard drives that you are but I'm really tempted to step it up and order the 3 TB drives.

Since you're going to be using software RAID with Disk Utility, are you expecting to see any performance issues on the iMac itself while you're in the middle of data transfers and doing other tasks?

Actually, I may not use the Caviar Black (still too expensive) and may instead go for the WD20EVDS drives (which works great running 24/7 in my HD DVR).

I tried out a RAID 1 setup with a pair of old Seagate FreeAgent Pro 750GB USB drives and did not notice any problems using my MBP while transferring data. In fact, I pulled the RAW drives from them (Seagate Barracuda 7200.10) and will use those in the OWC until I purchase a pair of 2 TB drives.

 

[HobeSoundDarryl]

why can't you benefit from software RAID

You can benefit from a software RAID setup. The benefit is the RAID setup. Hardware RAID is typically a faster RAID. However, the speed difference may not be noticeable enough for your application.

 

[HobeSoundDarryl]

I've been talking to a friend (who also works for me) and has a lot of expertise on systems (he's our guy when we need to do Linux servers, etc). He always uses software RAID, because he says he's been burned by hardware RAID. A controller adds another point of failure, and if it fails and gets replaced, there is no guarantee it will revive the old RAID as it was, in which case it has to be reconfigured with consequent data loss. RAID controllers are proprietary and if they aren't exactly the same, can be a problem as a replacement (even for identical hardware that has maybe just different firmware). And he is not the only one I have heard that from. So if you look at it that way, there is a benefit to software RAID.

Right. But that "another point of failure" stuff can apply to all kinds of things. Power to the hardware/software RAID. The firewire connection & cable. And so on. I'm not overly arguing that you should ONLY consider hardware RAID; instead, you should do whatever is best for you. You asked a question about which way to go. Head-to-head, I'd bet the hardware RAID outperforms the software RAID. But in only a 2-drive setup, the difference may not be enough to notice much.

 

[RaceTripper]

Right. But that "another point of failure" stuff can apply to all kinds of things. Power to the hardware/software RAID. The firewire connection & cable. And so on. I'm not overly arguing that you should ONLY consider hardware RAID; instead, you should do whatever is best for you. You asked a question about which way to go. Head-to-head, I'd bet the hardware RAID outperforms the software RAID. But in only a 2-drive setup, the difference may not be enough to notice much.

Actually, the OP asked, not me. I was already planning to do software RAID 1. If I wanted hardware RAID 1 then I bought the wrong enclosure.

 

[HobeSoundDarryl]

Sorry should have check for the OP.

 

[RaceTripper]

Sorry should have check for the OP.

NP. Just thought I'd clarify.

I got my OWC enclosure today. As it turns out, MicroCenter (and Best Buy) have a sale on Seagate Barracuda 2TB (ST320005N4A) drives for $89.99. Although they are the 5900 RPM drives, that suits me for a RAID 1 setup since I'm using it for bulk storage rather than as a work drive (I have a SSD internal for all my day-to-day working OS, apps, and data). The 7200 RPM drives would have cost twice that, give or take.

I used Disk Utility to set up the RAID 1. It's online and I have SuperDuper copying data over from an older, slower USB 1 TB drive.

 

[iMikeT]

NP. Just thought I'd clarify.

I got my OWC enclosure today. As it turns out, MicroCenter (and Best Buy) have a sale on Seagate Barracuda 2TB (ST320005N4A) drives for $89.99. Although they are the 5900 RPM drives, that suits me for a RAID 1 setup since I'm using it for bulk storage rather than as a work drive (I have a SSD internal for all my day-to-day working OS, apps, and data). The 7200 RPM drives would have cost twice that, give or take.

I used Disk Utility to set up the RAID 1. It's online and I have SuperDuper copying data over from an older, slower USB 1 TB drive.

Very nice. How would you rate that OWC enclosure? And how is your iMacs performance while transferring data?

 

[RaceTripper]

Very nice. How would you rate that OWC enclosure? And how is your iMacs performance while transferring data?

I am quite pleased with the enclosure. It looks great and is relatively quiet. I'm using this with my MBP (don't have an iMac). The performance is very satisfactory and noticeably better than the WD Studio FW800 external I have.

Note that I am using the OWC just as a dual bay FW800 enclosure (so I'm not using the hardware RAID 0). I have RAID 1 configured via the Apple Disk Utility.

I'll have my third drive Wednesday, so I'll test the RAID 1 recovery by swapping it in for one that is already there and make sure the RAID rebuilds correctly. I'd prefer to have two drives from different batches for normal use anyway. The two that are in there now are pretty close in ser#.

 

[RaceTripper]

I got my spare drive this week and decided to swap it in for one already running in the RAID 1. The swap worked fine. Diskutil recognized the RAID as degraded and rebuild it, but it took 20 freaking hours. It would have been faster to just reconfigure the RAID and restore from backup. Oh well, at least I know it works correctly and the volume did stay online and accessible the entire time.

 

[RaceTripper]

I have updated my system.

Micro Center has a sale this week on the Seagate Barracuda LP 2 TB for $79 so I picked one up to add to the three I have (2 in RAID 1, 1 spare) and bought another OWC enclosure. Now I have each OWC as a 4 TB hardware RAID 0 and I put the two together as a RAID 1 using Disk Utility. The result is I have a double FW800 enclosure 4 TB RAID 1+0. Using SuperDuper now to restore all my data from backup.

 

[iMikeT]

I have updated my system.

Micro Center has a sale this week on the Seagate Barracuda LP 2 TB for $79 so I picked one up to add to the three I have (2 in RAID 1, 1 spare) and bought another OWC enclosure. Now I have each OWC as a 4 TB hardware RAID 0 and I put the two together as a RAID 1 using Disk Utility. The result is I have a double FW800 enclosure 4 TB RAID 1+0. Using SuperDuper now to restore all my data from backup.

Very nice. Thanks for the update.

I was thinking about doing something similar as well. That is, getting two of these OWC 2-bay enclosures and going the RAID 1+0 (or 0+1) route dedicated solely to my media files. And that's media meaning all my iTunes content. I might need more considering that I am thinking about digitizing all of my DVDs. For something like this though, what I really prefer is a massive array or a NAS. But just going from a 2-bay to 4-bay enclosure, you'll see that the prices just aren't competitive.

How's your Mac handling all this in addition to its day-to-day tasks?

 

[RaceTripper]

Very nice. Thanks for the update.

I was thinking about doing something similar as well. That is, getting two of these OWC 2-bay enclosures and going the RAID 1+0 (or 0+1) route dedicated solely to my media files. And that's media meaning all my iTunes content. I might need more considering that I am thinking about digitizing all of my DVDs. For something like this though, what I really prefer is a massive array or a NAS. But just going from a 2-bay to 4-bay enclosure, you'll see that the prices just aren't competitive.

How's your Mac handling all this in addition to its day-to-day tasks?

It doesn't put any extra demands on my MBP. I have a 240GB SSD internal. That has most of my day-to-day data. The external is hosting extra media files, photos, and a bunch of test data for some software development I'm doing.

I am planning to start ripping some DVDs (I have about 500) for streaming to my AppleTV2 (I have 3).