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I was looking for an external drive enclosure with a RAID controller and found one in Newegg.

Looking at Wikipedia, I cannot find information on this "SAFE" terminology.

Is this a replacement for RAID or something? If so, why?

The feature list for the enclosure state:

SAFE33 (1/3 to SAFE mode & 2/3 to BIG mode)

SAFE50 (1/3 to SAFE mode & 1/2 to BIG mode)

What does that even mean?

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closed as off-topic by Tom O'Connor Jul 6 '13 at 7:38

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Questions about hardware or software used in a home setting are off-topic because they require answers that may not be practical for the business and support professionals here. You should try asking on Super User instead." – Tom O'Connor
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Apparently it isn't the only company: google.com/products/catalog?cid=15949196132441965667 –  Belmin Fernandez Nov 7 '10 at 23:48
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This is consumer grade hardware, not related to system administration, and comes with fancy new buzzwords to make abstract terminology like "RAID" more user friendly. –  Chris S Nov 8 '10 at 1:50
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According to the close dialog: "Questions on Server Fault are expected to generally relate to [...] professional desktop IT in some way". By that definition, the question is certainly relevant. –  Belmin Fernandez Nov 8 '10 at 2:04
    
@Chris It isn't just a buzzword. See @entens answer below w.r.t SAFE33 and SAFE50 –  Belmin Fernandez Nov 8 '10 at 2:58
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"professional desktop IT" doesn't appear anywhere in the FAQ and misrepresents what is stated there. Further; The buzzwords describe concepts that are simply odd combination of RAID, existing terminology can accurately describe the concept, and in a way any SA can easily understand. The terms are euphemisms invented using positive sounding words so that uninformed consumers would be more likely to buy the product. This does not diminish the technical merits of the product, but it's nothing new. –  Chris S Nov 8 '10 at 21:28

2 Answers 2

up vote 11 down vote accepted
  • FAST = RAID0
  • SAFE = RAID1
  • BIG = JBOD

SAFE33 and SAFE50 are modified and combined versions of RAID. You may want to refer to the Sans Digital's RAID definitions for more information. Official descriptions follow.

SAFE 33 RAID mode SAFE33 allows the creation of two hard drive volumes where 1/3 (33%) of the volume is used for mirroring and the rest is used for Spanning (Big). In comparison to SAFE (RAID 1) mode, which utilizes both hard drives for mirroring, SAFE33 increase storage space by setting aside a portion of disk space for regular data storage while performing mirror simultaneously.

SAFE33 Diagram

SAFE 50 RAID mode SAFE50 allows the creation of two hard drive volumes where 1/2 (50%) of the volume is used for mirroring and the rest is used for Spanning (Big). In comparison to SAFE (RAID 1) mode, which utilizes both hard drives for mirroring, SAFE50 increase storage space by setting aside a portion of disk space for regular data storage while performing mirror simultaneously.

SAFE50 Diagram

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Awesome. Thank you @entens. I thought it was just some consumer-friendly relabeling of RAID but apparently it's a bit more than that. –  Belmin Fernandez Nov 8 '10 at 2:57

This is a stupid marketing term by the company in question. This thing has been possible on Unix-y systems for quite a long time with software RAID (DM on Linux, SVM on Solaris, etc.).

For example, take two disks (sda and sdb); create two partitions on each (sda1, sda2; sdb1, sdb2). Mirror the first partition on the drives:

$ mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sda1 /dev/sdb1

And then concatenate the the second partition on each drive:

$ sudo mdadm --create --verbose /dev/md1 --level=linear --raid-devices=2 /dev/sda2 /dev/sdb2

Ta da. An SVM example under Solaris is left as an exercise for the reader.

Just because the typical home user does not know how to do this under the most common operating system available does not make it novel, nor make it worth creating a new term for it IMHO.

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