Why just JBOD/RAID 0 for enclosure?

[no name]

I've been looking for drive enclosures that have a network connection.

I saw one that was cheap, and would allow two drives BUT: It would only
allow JBOD.

Why would a manf do this? What's the point? Why wouldn't they allow
"nothing" or "JBOD" or "raid 1"?

 

[Arno Wagner]

I've been looking for drive enclosures that have a network connection.

I saw one that was cheap, and would allow two drives BUT: It would only
allow JBOD.

Why would a manf do this? What's the point? Why wouldn't they allow
"nothing" or "JBOD" or "raid 1"?

This limit likely saves a few cents on production, and, more
imortant, reduces the load on customer support because nobody
needs to ask what the different modes are.

So, until a significant fraction of the customers understand what
RAID1 is, only the worst possible configuration (thet nonetheless
will look the best to the incompetent) will be available.

Arno

 

[Rod Speed]

I've been looking for drive enclosures that have a network connection.

I saw one that was cheap, and would allow two drives BUT: It would only allow JBOD.

Why would a manf do this? What's the point?

That approach means that no one can stuff up the config.

Why wouldn't they allow "nothing" or "JBOD" or "raid 1"?

Presumably what they are using hardware wise cant do that.

 

[Yousuf Khan]

I've been looking for drive enclosures that have a network connection.

I saw one that was cheap, and would allow two drives BUT: It would only
allow JBOD.

Why would a manf do this? What's the point? Why wouldn't they allow
"nothing" or "JBOD" or "raid 1"?

What do you mean by "nothing"? JBOD is "nothing", Just a Bunch Of Disks.

There is a misconception that JBOD means a spanning of several disks,
aka concatenation. It doesn't mean that at all, JBOD can be turned into
any RAID configuration, including concatenation, with volume management
software (aka software RAID).

Yousuf Khan

 

[Arno Wagner]

What do you mean by "nothing"? JBOD is "nothing", Just a Bunch Of Disks.

There is a misconception that JBOD means a spanning of several disks,
aka concatenation. It doesn't mean that at all, JBOD can be turned into
any RAID configuration, including concatenation, with volume management
software (aka software RAID).

JBOD is the "idiot mode" and often means concatenation. It does not
have to as the term is indeed more general.

Arno

 

[no name]

What do you mean by "nothing"? JBOD is "nothing", Just a Bunch Of Disks.

There is a misconception that JBOD means a spanning of several disks,
aka concatenation.

It's a misconception that's shared by the vendors of some devices.

"Turn two discs into one large device" - and they're usually talking about
raid0 style "one drives dies all data has gone".

It doesn't mean that at all, JBOD can be turned into

 

[Arno Wagner]

What do you mean by "nothing"? JBOD is "nothing", Just a Bunch Of Disks.

There is a misconception that JBOD means a spanning of several disks,
aka concatenation.

[/QUOTE]

It's a misconception that's shared by the vendors of some devices.

Unfortunately, yes. JBOD should be avoided as term. Use APPEND
mode or the appropriate RAID level instead.

"Turn two discs into one large device" - and they're usually talking about
raid0 style "one drives dies all data has gone".

Indeed, but without the speed advantage of RAID0.

Arno

 

[bbbl67]

It's a misconception that's shared by the vendors of some devices.

"Turn two discs into one large device" - and they're usually talking about
raid0 style "one drives dies all data has gone".

Well, you said that this particular networked enclosure only supports
JBOD, which would indicate they are wasting no money on disk
management intelligence, just giving a network protocols intelligence
(e.g. CIFS, NFS, etc.). So I would say when they talk about JBOD, they
are talking about the real JBOD, not a concat or striping (RAID0),
otherwise they would've mentioned it themselves.

Yousuf Khan

 

[Squeeze]

bbbl67 wrote in news:b66d4f51-ac10-48d0-9069-fcfb30ff6b85@g17g2000prg.googlegroups.com

Well, you said that this particular networked enclosure only supports
JBOD, which would indicate they are wasting no money on disk
management intelligence, just giving a network protocols intelligence
(e.g. CIFS, NFS, etc.). So I would say when they talk about JBOD, they
are talking about the real JBOD, not a concat or striping (RAID0),
otherwise they would've mentioned it themselves.

They don't need to, because JBOD mode has nothing to do with RAID0,
only with spanning/concatenation. A volume made up of one or several disks logically lined up one after another, no fancy stuff.

 

[Thomas Maier-Komor]

I've been looking for drive enclosures that have a network connection.

I saw one that was cheap, and would allow two drives BUT: It would only
allow JBOD.

Why would a manf do this? What's the point? Why wouldn't they allow
"nothing" or "JBOD" or "raid 1"?

If this is really JBOD and not RAID0 or concat, then this absolutely
makes sense. JBOD has the significant advantage that you can use
software for RAID setup. Like this the setup is hardware independent and
can easily be transfered/moved to another host. So a dying enclosure or
HBA won't leave your RAID in an unusable state.

Additionally, JBOD enclosures are highly interesting for ZFS, which is
available on Solaris and BSD. ZFS is something like RAID and filesystem
in one, and therefore is able to handle a much bigger number of failure
modes, such as misdirect read/write, I/O data corruption on the datapath
and many more.

- Thomas

 

[Arno Wagner]

If this is really JBOD and not RAID0 or concat, then this absolutely
makes sense. JBOD has the significant advantage that you can use
software for RAID setup. Like this the setup is hardware independent and
can easily be transfered/moved to another host. So a dying enclosure or
HBA won't leave your RAID in an unusable state.

You can use software for any RAID level and it has been done for years.

Additionally, JBOD enclosures are highly interesting for ZFS, which is
available on Solaris and BSD. ZFS is something like RAID and filesystem
in one, and therefore is able to handle a much bigger number of failure
modes, such as misdirect read/write, I/O data corruption on the datapath
and many more.

As I said. However I highly doubt the creators of JBOD were even
aware of ZFS.

Arno