SATA JBODs for backup-to-disk

[David Boyer]

We know there are a lot of vendors offering SATA JBODs with either FC or
Ultra320 interfaces. They all pretty much offer hot-swap drives, but I
haven't seen any that package the individual drives in such a way that
they're designed to be portable/modular. You remove a bare drive in some
type of convenience tray, but not something protective that would facilitate
vault storage.

Has anyone seen any SATA JBODs where the drives are packaged in removable
cartridges that might be suitable for storage outside the JBOD?

Thanks!

 

[Nik Simpson]

We know there are a lot of vendors offering SATA JBODs with either FC or
Ultra320 interfaces. They all pretty much offer hot-swap drives, but I
haven't seen any that package the individual drives in such a way that
they're designed to be portable/modular. You remove a bare drive in some
type of convenience tray, but not something protective that would facilitate
vault storage.

Has anyone seen any SATA JBODs where the drives are packaged in removable
cartridges that might be suitable for storage outside the JBOD?

ProStor Systems in Colorado are doing something along those lines (see
www.prostorsytems.com) I think the reason you don't tend to see it as a
common feature is that for most backup-to-disk applications it would be
of dubious utility since each backup set spans multiple disks in order
to achieve the required throughput, so can't just pull a disk and take
them somewhere else to read the data, you'd have to pull the entire
stripe. In addition, most people who want long term archive storage are
still going with tape even if they use D2D for their frontline backup
application.

 

[Arno Wagner]

We know there are a lot of vendors offering SATA JBODs with either FC or
Ultra320 interfaces. They all pretty much offer hot-swap drives, but I
haven't seen any that package the individual drives in such a way that
they're designed to be portable/modular. You remove a bare drive in some
type of convenience tray, but not something protective that would facilitate
vault storage.

Has anyone seen any SATA JBODs where the drives are packaged in removable
cartridges that might be suitable for storage outside the JBOD?

First, JBOD is about the least suitable option for backup. Loose one disk
and loose everything.

Second, why not use eSATA disks directly?

Arno

 

[David Boyer]

First, JBOD is about the least suitable option for backup. Loose one disk
and loose everything.

If you lose one disk, you shouldn't lose everything IF the JBOD is
configured properly. You can usually use mirroring, RAID 5, RAID 6, and RAID
10, and any other methods you would use to survive one or more disk
failures. Depending on the JBOD vendor, the array config is stored on each
of the physical disks, so you can remove a disk or diskset and pop it in a
year later and have it back online just by installing the drives. We've been
doing backups to a 6TB SATA JBOD for nearly two years, and it works great.
The problem with our JBOD is that drives are hot-swappable, but aren't
otherwise designed to be modular.

Second, why not use eSATA disks directly?

eSATA disks are also an option we're looking at.

 

[Arno Wagner]

If you lose one disk, you shouldn't lose everything IF the JBOD is
configured properly. You can usually use mirroring, RAID 5, RAID 6, and RAID
10, and any other methods you would use to survive one or more disk
failures.

JBOD is a RAID mode. It just places the individual disks sectors one
after another and supports differently sized disks. JBOD is not
RAID 1/5/10 or any other redundant RAID level. JBOD is sometimes
called APPEND mode (e.g. by the Linux LVM).

Depending on the JBOD vendor, the array config is stored on each
of the physical disks, so you can remove a disk or diskset and pop it in a
year later and have it back online just by installing the drives. We've been
doing backups to a 6TB SATA JBOD for nearly two years, and it works great.
The problem with our JBOD is that drives are hot-swappable, but aren't
otherwise designed to be modular.

Maybe you mean something else than the Just a Bunch Of Disks RAID
mode here?

Arno

 

[Yousuf Khan]

JBOD is a RAID mode. It just places the individual disks sectors one
after another and supports differently sized disks. JBOD is not
RAID 1/5/10 or any other redundant RAID level. JBOD is sometimes
called APPEND mode (e.g. by the Linux LVM).


Maybe you mean something else than the Just a Bunch Of Disks RAID
mode here?

To me, JBOD means "Just a Bunch Of Disks". That's a system where each of
the individual disks is visible to the operating system in their raw
individual disk form, rather than visible to the OS as a virtual volume
pre-virtualized by a hardware RAID disk array. JBODs can then be
volumized by software RAID into concats, stripes, mirrors, RAID 5, and
other RAID modes.

Yousuf Khan

 

[Arno Wagner]

To me, JBOD means "Just a Bunch Of Disks". That's a system where each of
the individual disks is visible to the operating system in their raw
individual disk form, rather than visible to the OS as a virtual volume
pre-virtualized by a hardware RAID disk array. JBODs can then be
volumized by software RAID into concats, stripes, mirrors, RAID 5, and
other RAID modes.

Well, then you should adjust your language to the standards that cover
this, unless you want to be misunderstood. JBOD does mean "Just a
Bunch Of Disks", but "Just a Bunch Of Disks" is a RAID mode
also known as SPAN, concat or append mode.

A reference:

http://en.wikipedia.org/wiki/Standard_RAID_levels

Arno

 

[David Boyer]

See Nik's reply above? That's what a useful response looks like. He actually
answered the question.

You can cite Wikipedia all day as though it's implicitly authoritative, but
the reality is that numerous vendors are selling JBODs that don't match the
"standard" definition. Maybe they need to consult with wikipedia or Arno
before those items go to market. JBOD seems to be a broad term applied to
multi-disk SAN-type enclosures that aren't being connected to a fabric.

Maybe I should have said "multi drive SATA enclosure" instead of JBOD. Now,
can you answer the question, or is nit-picking pretty much the limit of what
you can contribute?

 

[Arno Wagner]

See Nik's reply above? That's what a useful response looks like. He actually
answered the question.

You can cite Wikipedia all day as though it's implicitly authoritative, but
the reality is that numerous vendors are selling JBODs that don't match the
"standard" definition. Maybe they need to consult with wikipedia or Arno
before those items go to market.

Maybe they need to read up waht terms mean before using them.

JBOD seems to be a broad term applied to
multi-disk SAN-type enclosures that aren't being connected to a fabric.

Maybe in marketing-speak. In engineering it has a meaning that is
the one e.g. described in wikipedia. You can also do a google-search
for the term and see what you find there or you can look into
manufacturer documentation.

Maybe I should have said "multi drive SATA enclosure" instead of JBOD.

Now there is a term that actually matches your intention.

Now,
can you answer the question, or is nit-picking pretty much the limit of what
you can contribute?

Term clarification is not nit-picking. It is essential for meaningful
communication. Even more when vendors start to use terms that already
have a different meaning for their own thing, maybe because it sounds
cool.

As to your original question, no, the only variant I know is
using individual eSATA disks, since they are packaged for separate
storage. In principle the external SATA RAID enclosures you are talking
about can all use eSATA instead of internal SATA, since it is identical
on the software side. On the hardware side, you may need to stay within
SATA cable lenght limits (1m) to make it work with internal SATA
controllers.

But quite frankly, as with regard to resonable disk protection
for storege, I am less than impressed with current eSATA enclosures.
The ones I havve seen do not have reasonable shock protection (i.e.
they are pretty equivalent to a bare drive), no moisture seals and
no dust seals.

I think the best option is to use the internal removable bays
and add your own packaging. Depending on what you need an
anti-static bag and two layers of high-quality bubble wrap may be
enough. There are also HDD shiping containers that have 5cm
of foam-rubber in all directions. Combine that with an anti-static
bag and there you go. Yes, I know this is stupid, but there seems
to be no market for what you want. And yes, I agree that this
would be a good idea to have available.

Arno

 

[Arno Wagner]

See Nik's reply above? That's what a useful response looks like. He actually
answered the question.

Well, as to that, ProStore simply seems to use 2.5" laptop disks,
which are inherently more robust than 3.5" disks (because of the
intended application). It does not look to me like they actually
add much of value to the bare drive. And of course you take
a performance and a cost and a capacity hit with this approach.

Arno

 

[Yousuf Khan]

Well, then you should adjust your language to the standards that cover
this, unless you want to be misunderstood. JBOD does mean "Just a
Bunch Of Disks", but "Just a Bunch Of Disks" is a RAID mode
also known as SPAN, concat or append mode.

A reference:

http://en.wikipedia.org/wiki/Standard_RAID_levels

You're going to quote Wikipedia to me as an authorative source? Well, I
can show you a site just as authorative that says differently.

What is JBOD? - A Word Definition From the Webopedia Computer Dictionary
"Just a Bunch Of Disks Used to refer to hard disks that aren't
configured according to RAID -- a subsystem of disk drives that improves
performance and fault tolerance."
http://www.webopedia.com/TERM/J/JBOD.html

 

[Arno Wagner]

You're going to quote Wikipedia to me as an authorative source? Well, I
can show you a site just as authorative that says differently.

No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage. There is no authorative
siurce as of now, as with a lot other CE/CS terms. But there is common
usage. Vendor brochure usage does not count, vendors will mangle terms
to an arbitrary degree if they think something sounds cool. Just
think of Windows XP. XP means "experimental", period. It has been
meaning that for decades and comes from airplane model designations.
But for MS it means "experience" and they have zero justification
for it.

What is JBOD? - A Word Definition From the Webopedia Computer Dictionary
"Just a Bunch Of Disks Used to refer to hard disks that aren't
configured according to RAID -- a subsystem of disk drives that improves
performance and fault tolerance."
http://www.webopedia.com/TERM/J/JBOD.html

Well, that is incomplete but not really add odds with the Wikipedia
definition, now is it? They just stress a bit more that JBOD
does not have redundancy in a bit nebulous way. Whether you want to
call JBOD (or RAID0 for that matter) a RAID mode or not, is a
matter of taste. The ''R'' is certainly not in them. But if
you relax on the ''R'', then RAID0 and SPAM/APPEND/JBOD are
both RAID modes.

Arno

 

[Steve Cousins]

No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage.

I would not say this is "common usage". I've been using JBOD's for many
years and they have mostly had nothing to do with RAID. If you get an
enclosure full of drives it is either a RAID unit or a JBOD. The only
cross-over has been with the 3Ware RAID cards where if you want to use a
drive by itself, not part of a RAID set, then you specify it as a JBOD
drive.

Whether you want to
call JBOD (or RAID0 for that matter) a RAID mode or not, is a
matter of taste. The ''R'' is certainly not in them. But if
you relax on the ''R'', then RAID0 and SPAM/APPEND/JBOD are
both RAID modes.

JBOD has no "A" in it either. They are not part of an array. No one disk
has anything to do with any of the other disks. That is the whole idea
of JBOD's (as far as I have ever heard).

 

[Nik Simpson]

I would not say this is "common usage". I've been using JBOD's for many
years and they have mostly had nothing to do with RAID. If you get an
enclosure full of drives it is either a RAID unit or a JBOD. The only
cross-over has been with the 3Ware RAID cards where if you want to use a
drive by itself, not part of a RAID set, then you specify it as a JBOD
drive.

Expansion enclosures for raid storage systems are usually JBOD, they get
their RAID capabilities from the controller in the main enclosure. So
it's a bit too simple to say that JBOD is only used in applications
without RAID.

 

[Steve Cousins]

Expansion enclosures for raid storage systems are usually JBOD, they
get their RAID capabilities from the controller in the main enclosure.
So it's a bit too simple to say that JBOD is only used in applications
without RAID.

Sure they can be used in RAID applications. I use them for software RAID
all the time. But there is nothing about them being JBOD that implies
RAID. That RAID people use JBOD's doesn't mean that the term JBOD
implies RAID.

 

[Yousuf Khan]

No. I am giving you one reference that explains it and I am telling
you that what is there is the common usage. There is no authorative
siurce as of now, as with a lot other CE/CS terms. But there is common
usage. Vendor brochure usage does not count, vendors will mangle terms
to an arbitrary degree if they think something sounds cool. Just
think of Windows XP. XP means "experimental", period. It has been
meaning that for decades and comes from airplane model designations.
But for MS it means "experience" and they have zero justification
for it.

I worked for a reseller of storage systems for years, and that is the
first time I've ever even heard of JBOD being described as another term
for concatenation. To me there was never any confusion about the term,
nor any hint that the term was under confusion, until this discussion.

Well, that is incomplete but not really add odds with the Wikipedia
definition, now is it? They just stress a bit more that JBOD
does not have redundancy in a bit nebulous way. Whether you want to
call JBOD (or RAID0 for that matter) a RAID mode or not, is a
matter of taste. The ''R'' is certainly not in them. But if
you relax on the ''R'', then RAID0 and SPAM/APPEND/JBOD are
both RAID modes.

Read the discussion forums in the Wikipedia entry about that JBOD term.
It is being described as being completely wrong by most of the
discussees. I will be editing that definition from Wikipedia in a few
days when I have some time. It's completely wrong.

Yousuf Khan

 

[Yousuf Khan]

JBOD has no "A" in it either. They are not part of an array. No one disk
has anything to do with any of the other disks. That is the whole idea
of JBOD's (as far as I have ever heard).

That Wikipedia entry is completely f*ked up, it's time to change it.

Yousuf Khan

 

[Yousuf Khan]

Expansion enclosures for raid storage systems are usually JBOD, they get
their RAID capabilities from the controller in the main enclosure. So
it's a bit too simple to say that JBOD is only used in applications
without RAID.

It's very simple, if you can see and control the disks individually in
the OS, then they are JBODs. If the OS just sees the volume and not the
underlying disks, then it's not JBOD.

Yousuf Khan

 

[Arno Wagner]

That Wikipedia entry is completely f*ked up, it's time to change it.

Change the rest of the explanations on the web as well, while you are
at it.

Arno

 

[Folkert Rienstra]

To me, JBOD means "Just a Bunch Of Disks". That's a system where
each of the individual disks is visible to the operating system in their
raw individual disk form, rather than visible to the OS as a virtual
volume pre-virtualized by a hardware RAID disk array. JBODs can
then be volumized by software RAID into concats, stripes, mirrors,
RAID 5, and other RAID modes.

Pity then that even the OP had something quite different in mind when he
mentioned "JBOD":

"We know there are a lot of vendors offering SATA JBODs
*with either FC or Ultra320 interfaces*"

"Depending on the *JBOD vendor*, *the array config* is stored on each
of the physical disks, so you can remove a disk or diskset and pop it
in a year later and have it back online just by installing the drives".

Obviously his 'JBOD's have internal array controllers.