Re: SATA JBODs for backup-to-disk

Previously David Boyer <spmdecoy2003@xxxxxxxxxxx> wrote:
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" <me@xxxxxxxxxxx> wrote in message
news:5dadijF33ud2mU1@xxxxxxxxxxxxxxxxxxxxx
Previously Yousuf Khan <bbbl67@xxxxxxxxx> wrote:
Arno Wagner wrote:
Previously David Boyer <spmdecoy2003@xxxxxxxxxxx> wrote:
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?


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


.

Relevant Pages

  • Re: SATA JBODs for backup-to-disk
    ... Maybe I should have said "multi drive SATA enclosure" instead of JBOD. ... You can usually use mirroring, RAID 5, RAID 6, and ... after another and supports differently sized disks. ... but "Just a Bunch Of Disks" is a RAID mode ...
    (comp.sys.ibm.pc.hardware.storage)
  • Re: SATA JBODs for backup-to-disk
    ... you that what is there is the common usage. ... "Just a Bunch Of Disks Used to refer to hard disks that aren't ... They just stress a bit more that JBOD ... call JBOD a RAID mode or not, ...
    (comp.sys.ibm.pc.hardware.storage)
  • Re: SATA JBODs for backup-to-disk
    ... You can usually use mirroring, RAID 5, RAID 6, and RAID ... JBOD is a RAID mode. ... after another and supports differently sized disks. ...
    (comp.sys.ibm.pc.hardware.storage)
  • Re: ZFS and JBODs
    ... Why would a JBOD ... To clarify - 3511 with 500gb work fine with a head unit. ... with writing do disks - probably a firmware problem, or sata-router, or... ... I guess you're referring to a raid controller? ...
    (comp.unix.solaris)
  • Re: SATA JBODs for backup-to-disk
    ... They all pretty much offer hot-swap drives, ... JBOD is about the least suitable option for backup. ... You can usually use mirroring, RAID 5, RAID 6, and RAID ... after another and supports differently sized disks. ...
    (comp.sys.ibm.pc.hardware.storage)