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Author Topic: expanding / growing JBOD  (Read 14668 times)

hunglow

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expanding / growing JBOD
« on: December 03, 2008, 06:41:37 PM »

HI all,

I currently have a 343 with 2 x1 TB drives in it formatted to JBOD.  I would like to add another two and expand the current logical volume without losing the data currently on them.  I understand that when I install the two new drives they will need to be formatted but can I add them to the existing JBOD with out formatting all 4.  The manual is silent on this.  I know raid migration is not supported but JBOD (spanning) is not really raid.

Thanks
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fordem

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Re: expanding / growing JBOD
« Reply #1 on: December 03, 2008, 06:51:23 PM »

I can't answer your question - but - it prompts me to ask another.

You're asking about expanding a JBOD array without losing data - are you aware that if any one disk in that array fails, you lose ALL of the data in the array?

Given that fact, and that each disk added to the array increases the probability of data loss - is the convenience of JBOD really worth the risk?

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RAID1 is for disk redundancy - NOT data backup - don't confuse the two.

hunglow

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Re: expanding / growing JBOD
« Reply #2 on: December 03, 2008, 07:50:02 PM »

With JBOD if one disk is lost then the information on the others can be read.  Raid 0 with striping will give the result you are describing.  Eventually I'll get another 343 and mirror the first.

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hunglow

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Re: expanding / growing JBOD
« Reply #3 on: December 03, 2008, 10:03:55 PM »

I had sent a email to Dlink support earlier in the week and received this reply today.  Seems very positive and helpful.



"Thank you for your email.


It shouldn't affect the current 2 HDD in JBOD but we have to verify and
test it as well.


We will get back to you within 24-48 hrs when the testing is complete.

 
 

Kind Regards,

Technical Support Team"
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fordem

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Re: expanding / growing JBOD
« Reply #4 on: December 04, 2008, 04:48:38 AM »

With JBOD if one disk is lost then the information on the others can be read.  Raid 0 with striping will give the result you are describing.  Eventually I'll get another 343 and mirror the first.



Have you personally tested this - if not - I suggest you do.

I have not tested it on the DNS-343, but on the smaller DNS-323, if you fail either disk in a JBOD array, the data is lost, even if it is on the disk that is still functional.
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RAID1 is for disk redundancy - NOT data backup - don't confuse the two.

hunglow

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Re: expanding / growing JBOD
« Reply #5 on: December 04, 2008, 10:23:00 PM »

That a good point.  I had taken the word of others but the dlink implementation might be different somehow.  Just need to figure out how to simulate a realistic test without risking anything with my limited excess HDD.
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fordem

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Re: expanding / growing JBOD
« Reply #6 on: December 05, 2008, 04:12:27 AM »

Based on that response - I'd say you're already risking everything - it sounds like you have no backup.
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RAID1 is for disk redundancy - NOT data backup - don't confuse the two.

JavaLawyer

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Re: expanding / growing JBOD
« Reply #7 on: December 05, 2008, 07:24:05 AM »

Unless you already have your data backup elsewhere, the configuration you are suggesting is not wise.  If you expand the JBOD to 4x1TB, you can easily lose 4TB of data if one drive fails.  Every drive you add increases the number of failure points.

If you don't have a backup, then you should at least mirror the 2x1TB JBOD in the remaining two slots and hold off expanding your storage space until you can purchase a second 343.
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There's no such thing as too many backups FFC

hunglow

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Re: expanding / growing JBOD
« Reply #8 on: December 09, 2008, 07:08:45 PM »

For those who have an interest, this is the reply I received from Dlink support.  A bit disappointing as many, like I, would have purchased a 4 bay NAS with the view of starting small and expanding it.  Other brands are able to do it so it is possible with the operating system and cpu power available to the 343.  Dlink just needs to implement it.


"The 2 HDDs cannot be added to the existing JBOD logical drive. It will
create a new JBOD volume or logical drive for the 2 HDDs. It shouldn't
affect the existing JBOD logical drive but we recommend backing up your
DATA for safety purposes.


If you want to have one JBOD logical drive for 4 HDDs then you need to
remake/recreate the JBOD array for all HDDs. Make sure to back up your
DATA."



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MikeR2

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Re: expanding / growing JBOD
« Reply #9 on: March 03, 2009, 01:56:22 PM »

Folks at D-Link need to understand what scalability really means,
and stop advertizing the 343 as scalable.
It certainly should not mean "buy another 343 to back up data on
the first!"

Mike
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fordem

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Re: expanding / growing JBOD
« Reply #10 on: March 03, 2009, 04:18:17 PM »

Folks at D-Link need to understand what scalability really means,
and stop advertizing the 343 as scalable.
It certainly should not mean "buy another 343 to back up data on
the first!"

Mike


If you don't mind my asking - what does scalability have to do with the need for backup?  They are completely unrelated.

Quote from: Wikipedia
In telecommunications and software engineering, scalability is a desirable property of a system, a network, or a process, which indicates its ability to either handle growing amounts of work in a graceful manner, or to be readily enlarged.

In this case, the description of a NAS as scaleable, would refer to it's ability to be readily enlarged - and I 'm not going to enter into a debate on whether the DNS-343 is scaleable or not, since that is not relevant to the point I wish to make.

Whether or not is is scaleable, the data still needs to be backed up - and - if it is indeed scaleable, then your backup medium should also scale.

And if
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RAID1 is for disk redundancy - NOT data backup - don't confuse the two.

MikeR2

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Re: expanding / growing JBOD
« Reply #11 on: March 05, 2009, 10:47:22 PM »

What scalable should means is what DLINK advertises on the 343:

"you can easily insert up to 4 SATA drives without any tools or attaching any cables. Plus, the DNS-343 is a scalable solution, allowing you to start off with one SATA hard disk drive (HDD) and add up to 3 more as you grow."

But a quote from Wikipedia is always a nice touch :)

What you got here is one irate customer. And what this customer was told by the techs is to go ahead and format the second drive he bought per their instructions. This is after voicing my concern that indications were that the unit was trying to reformat my first drive (with data). So what you hear everyone saying at DLINK is to first backup your data. Well duh!

The "Noob" qualifier may apply to me on this site, but I'm not exactly new to the business.
First of all, a file server will outgrow any other storage medium one may have, especially with the advent of TB-size drives. So how does one back up data from one's server? Buying a second server? And why does it need to reformat drive 1 from scratch when I add drive 2? And I'm not talking about switching RAID mode either.

So I was led to format the drive in bay 2 per the tech's instructions. However things did not happen as the tech had described, and I lost everything.

We each have our needs. Mine were perfectly answered by DLINK in the quote above. Why would I possibly need or want to backup data on the first drive to simply add a second or third drive? I have done it for the last 25 years on my computers at home and at work without. Why does the 343 need to reformat drive 1? Who knows? Certainly not the techs I spoke to. Sorry, I'm venting now.

Anyway, no, I did not lose any data. I learned my lessons 25 years ago when I did not have a backup and lost 6 month worth of work. I bought the 343 primarily to back up the data from my computers' hard drives and to have quick access to data currently stored on over 500 DVDs. All I lost is a lot of work and respect for a company I used to trust.

Respectfully.
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fordem

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Re: expanding / growing JBOD
« Reply #12 on: March 06, 2009, 09:47:28 AM »

So what you hear everyone saying at DLINK is to first backup your data. Well duh!

The "Noob" qualifier may apply to me on this site, but I'm not exactly new to the business.

It may be irritating to some of us (me included), but, tech support often has no clue as to the skill & experience levels of the endusers - it is a required assumption, that the enduser is clueless - this is the safest approach, and if the complaints of data loss from D-Link DNS-3x3 users that I have seen are anything to go by, you're the exception rather than the rule.

Take a look at my signature - there are many end users who have asked what the difference is - I'm sure you already know.

Quote
First of all, a file server will outgrow any other storage medium one may have, especially with the advent of TB-size drives. So how does one back up data from one's server? Buying a second server?

This is of no relevance - if outgrowing the storage medium is the concern, then perhaps a SAN solution should be considered - but even with a SAN solution, there will still be the need to backup the data - but - let me not go there, no point in preaching to the choir, is there?

Quote
And why does it need to reformat drive 1 from scratch when I add drive 2? And I'm not talking about switching RAID mode either.

So I was led to format the drive in bay 2 per the tech's instructions. However things did not happen as the tech had described, and I lost everything.

That I have no explanation for - it's not supposed to that - but - that's what backups are for, when things don't go as they should.

Quote
We each have our needs. Mine were perfectly answered by DLINK in the quote above. Why would I possibly need or want to backup data on the first drive to simply add a second or third drive? I have done it for the last 25 years on my computers at home and at work without. Why does the 343 need to reformat drive 1? Who knows? Certainly not the techs I spoke to. Sorry, I'm venting now.

Anyway, no, I did not lose any data. I learned my lessons 25 years ago when I did not have a backup and lost 6 month worth of work. I bought the 343 primarily to back up the data from my computers' hard drives and to have quick access to data currently stored on over 500 DVDs. All I lost is a lot of work and respect for a company I used to trust.

Respectfully.


No further comment, no arguements - I learned that lesson around the same time and in pretty much the same way.
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mig

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Re: expanding / growing JBOD
« Reply #13 on: March 06, 2009, 09:52:48 AM »

What scalable should means is...

Perhaps the Data Robotic's Drobo has the scalability your require?
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ECF

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Re: expanding / growing JBOD
« Reply #14 on: March 10, 2009, 10:55:33 AM »

MikeR2

When you speak of scalability are you referring to a Grow task as seen in many SAN's device to expand the logical drive volume?
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