D-Link Network Storage > DNS-343

Is this software or hardware RAID?

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In reading about this product and other NAS products, many of them use some form of linux.  However, the documentation is sparse as to the method of RAID.  Does this product use hardware or software RAID.  Hardware is preferable to me personally.

If you give me a day or two I will be able to look that answer up for you, I don't know off hand.

Software RAID

If it is software RAID, I wonder what level of confidence can be placed in it.  I know that mirroring is relatively simple to do software wise and thus if there's a problem hopefully at least one of the drives has the right thing.

Drives that have been RAID 5 together are not so simple.

I've heard varying information on software RAID.

Does anyone have any experience using software RAID 5...?  Is it pretty stable...?

The question of software vs hardware RAID in a device like this is an oversimplification.  What do you mean by "hardware RAID"?  That the signals to the disk are controlled by TTL logic chips or an ASIC?  Hardware RAID implementations will normally have an embedded CPU of some sort.  That CPU runs a program, performing the same sort of operations as would a driver in a general purpose computer system.  The reason hardware implementations may be considered more reliable is that they operate in a much more well-defined space.  A driver in an operating system has to cope with a much larger range of possible environmental variables - interrupts, locking issues on multi-core systems, a wide variety of hardware platforms, a huge variety of competing software, not all of which may be well-behaved, even different versions of host operating system.  All these things are controlled in RAID cards.  But to a large extent they are also controlled in dedicated purpose devices like this.  Yes, there is a version of Linux running under the covers, but the version, the software environment, the hardware, the cpu - everything is fixed so that a test suite can be much more comprehensive than in an environment where these variables aren't controlled.  Then you also have the advantages of "software" implementations.  You can make changes much more easily.  In a version of RAID on a card, if subtle bugs are discovered (and they very often will be), does the manufacturer recall all the cards?  No.  But in a software implementation, the manufacturer can issue updates, as Dlink has done here.  Another advantage of using an open source implementation as a base is that the software has been through a very wide and rigorous test process.  For my money, a device like the Dlink NAS (and others that are similar) provides both the flexibility of an upgradeable implementation with the consistency of locked down hardware and software.


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