Promise R4 or R6 as boot drive

Discussion in 'Mac Accessories' started by cschmelz, Feb 19, 2013.

  1. cschmelz macrumors 6502

    Jun 6, 2007
    Is anyone using a Promise R4 or R6 as a boot drive?

    I'm in the market for a new iMac (current one is 2010 without thunderbolt) and need a larger drive array and an array with RAID 5 or 6 redundency would be nice.

    Given the R4 and R6 push over 500mb/sec, why isn't anyone using them as boot drives instead of paying a lot of money for a Fusion Drive setup?

    Wouldn't using the RAID as a boot give you 1) great performance on par with SSD (maybe not for small random accesses however) 2) redundency and 3) huge amounts of volume.
  2. utekineir macrumors 6502

    Feb 20, 2008
    if you have the cash to spend on a promise tb setup, you probably have the cash to spend on a 500mb/s ssd for your os. you also probably have the computer knowhow in terms of managing files to make a fusion drive unnecessary.

    Personally I prefer to keep os and data that should be backed (work/media/documents/etc) up on seperate volumes. Just makes for a much easier time if you ever have to wipe out the os.
  3. FCPEditor35 macrumors newbie

    Feb 19, 2013
    CalDigit's new USB 3.0 drive for mac has an SSD, and can get speeds up to 430MB/s which is on a par with Thunderbolt. It can be used as boot drive also.

    It would be better to use a single drive solution as a boot drive. The R4/R6 is too much for a bootable drive set up. The CalDigit drive is also bus powered if used with the SSD, which makes for a simple workflow, and less clutter!
  4. cschmelz thread starter macrumors 6502

    Jun 6, 2007
    But why exactly is the R6 'too much' for a boot drive setup? Super high speeds, low latency, huge capacity.... Yeah it is expensive but it would be quite fast, reliable (setup as RAID 5+spare or RAID 6) and seemingly dependable....
  5. FCPEditor35 macrumors newbie

    Feb 19, 2013
    Check out this speed test of the R6 on youtube:

    It is slower than the CalDigit drive I suggested when it's in RAID 5. It's a bit faster in RAID 0, but that won't give you the single drive redundancy.

    Having a big unit like that for a boot disk will be noisy, and take up a lot of space. I'd prefer a single drive like the AV Pro, as it is fast, and one cable to the Mac. It's also an SSD not a 3.5" HDD, so it can read the data instantly, unlike a traditional HDD that has to spin up to read the data.
  6. flynz4 macrumors 68040

    Aug 9, 2009
    Portland, OR
    Disk bandwidth (MB/s) is the most common benchmarked item... yet is the least important on how fast your system will run. Instead... IOPS are the predominate factor... unfortunately, they are still hard to measure.

    Bandwidth differences between HDDs and SSDs are relatively small (less than 10X). OTOH... the difference between IOPS on a SSD vs HDD might be 100X - 1000X. IOPS is what makes your machine fly.

    Regarding small random accesses. Your disk activity is likely to be about 90% small random reads and most of the rest are probably small random writes. This is where SSD shine. Large sequential access are relatively rare.

    If you would like having a car analogy:

    Car A: 0-60 in 2 minutes, with a top speed of 250 MPH
    Car B: 0-60 in 5 seconds, with a top speed of 200 MHP

    Which car will feel faster.. or be safer if you need to pass someone? Acceleration = IOPS. Top speed = MB/s. The later doesn't matter.

    BTW: I own a Pegasus R4 and it is great for bulk storage. Right now... it will be used in conjunction with my 768GB SSD in my (soon to be delivered) iMac. In a couple of years (or sooner)... when my next iMac has 2TB of SSD, the Pegasus R4 it will probably be relegated to a Mac Mini as a media server.

  7. cschmelz thread starter macrumors 6502

    Jun 6, 2007
    That makes a lot of sense. Thanks.

    So probably I should go ahead and get the Synology DS1512+ and load it up with drives, attach it to the network and use that for my media library and backup duty and then forget about the Promise.

    I have ripped all my owned movies to iTunes so they are easy to load on my iPad for traveling or for the AppleTV on the TVs in the house.

    My biggest concern about going NAS vs DAS is the issues I've read about with the Synology (or any NAS) file system and file name length limitations compared to NFS+.

    The solution I guess is to use a cheap large hard drive locally to store the media library (maybe a WD 4gb setup via FW800) and then commit all my backups to the Synology DS1512+.

    Later, if I decide I want to splurge on the Promse I can do that (but only after buying a 2012 iMac, either with Fusion or with a large, thunderbolt SSD as a boot drive.

    That makes sense?
  8. flynz4, Feb 19, 2013
    Last edited: Feb 19, 2013

    flynz4 macrumors 68040

    Aug 9, 2009
    Portland, OR
    Promise Pegasus is a fantastic DAS. It makes most sense if you have data that requires high performance... but does not comfortably fit in an SSD.

    Anything that streams... does not need high performance. Any old HDD can keep up with streaming media.

    If you have a very large Aperture database, which does not fit affordably in an SSD is great for the Pegasus. However... as SSD's fall in price... the market for fast arrays of HDDs decreases.

    Regarding backup... I agree that backing up to a NAS is the most convenient of devices... especially for laptops. If you have to plug in your laptop to have it back-up... it will rarely happen for most people. Even an iMac is best with network backup... because you can physically keep the backup drive away from the iMac in a different part of the house... or in a secure location. That way, if someone does a smash & grab of your computer... it is unlikely that they get your backup data along with the computer itself.

    At the same time... I am reminded a few years ago when Apple changed its backup... and many of the NAS units stopped working until they had a firmware update sometime later. For me... it is just not worth that possible hassle... so I use Time Capsules. They are stored away in a remote location of the house... and they have been trouble free.

    There is nothing wrong in theory of having your boot drive be external. However, I really hate doing that personally. Maybe it is superstition... or maybe it is the knowledge of one of the biggest issues in stability of a datacenter is technicians unplugging the wrong wire. Just a few weeks ago... there was someone reporting here on MR of a corrupted HDD because his wife yanked the wrong cord.

    That is one reason I chose the 768GB SSD for my new iMac. I wish I could get more internal capacity... but this will work for me... along with my Pegasus R4. I expect that this will be the last computer that I own that will need an external array... as SSD capacities will be increasing dramatically over the next few years.


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