Two HDDs combined - DiscussWorldIssues - Socio-Economic Religion and Political Uncensored Debate

**toreesi** · 03-24-2012, 10:03 PM

I think there is a small chance I have asked this before, as I have been thinking about it off and on for a while now, but is it possible to convince an OS that two HDDs are in fact one big one? If it is possible, what would the pros and cons be?

I am asking now as it has come up again due to me htpc [running ubuntu] has one drive that is nearly full and the other one is only partially used. I am using XBMC to watch and listen to things and I can easily add another source but that only works well in library mode. When not in library mode you have to navigate folders and having two folders for movies would be a pain when trying to locate things.

Alternatively, I might try in putting some of my movie folders on the other drive but link to them from the previous place and see if XBMC is happy with that. I know some programs are happy to accept a short cut as a folder...

**Relsenlilky** · 03-24-2012, 11:40 PM

JBOD or RAID.
Lots of information if you search for those.

**igs00r** · 03-24-2012, 11:49 PM

http://www.davelachapelle.ca/guides/ubuntu-lvm-guide/

**toreesi** · 03-25-2012, 01:09 AM

RAID doesn't seem to have anything that does it, or if it does, its tech speak is a little beyond me at this point in time. JBOD seems ambiguous as it appears to represent two completely different things. However, JBOD has brought me closer to concatenation/spanning which I guess is what I am after. However, even though I know the advantages of doing it, I do not not if there are any known disadvantages. I can see that there might be some drama at the boundaries but can't be sure of that.

Also, would it be possible to combine concatenation and raid? Like if I had 2 x 1 TB HHDs in one "span" could I RAID them so that they are backed up in another 2 x 1 TB HDDs in a "span"?

Edit: Also, when I first saw that "fish slapping maniac" link, I thought it might be to some funny guy going on about drugs or some such...completely missed the "la" part...

**QHdy5Z3A** · 03-25-2012, 01:20 AM

is it possible to convince an OS that two HDDs are in fact one big one? If it is possible, what would the pros and cons be?

Yep, but if one disk dies, you lose all data.
Better to buy a new larger HDD & clone the existing one.

**toreesi** · 03-25-2012, 01:25 AM

Yep, but if one disk dies, you lose all data.
Better to buy a new larger HDD & clone the existing one.

*Grumble*Grumble* The problem with computing these days, everything always needs updating!

Eventually when finances are right I'll finally build that NAS...

**Dapnoinaacale** · 03-25-2012, 03:14 AM

lvm will do the same. but personally i would just mount thec2 volumes on the nas.

**excivaamome** · 03-25-2012, 07:19 PM

Raid can be used to make 2 hard drives appear as a single drive.

Using a RAID 0 set, data is divided into discrete blocks and written to each drive in an alternating fashion (called striping), i.e. block 1 to drive 1, block 2 to drive 2, block 3 to drive 1.
When using 2 drives this makes a raid volume that is twice the size of the smallest physical drive, and as the data is striped across both drives the read/write performance is almost doubled.

The flaws to this approach are that the resultant raid volume has double the chance of catastrophic failure, as a failure in either physical drive will result in the loss of ALL data.
Additionally, you would need to copy all of the data off the drives before creating a raid volume, as all data on the drives is lost when the volume is initially created.

There is some good info on the Wikipedia page about raid. I would personally recommend against a RAID 0 set, unless you maintain a regular backup of the data.
http://en.wikipedia.org/wiki/RAID

**Drugmachine** · 03-26-2012, 03:58 AM

In Windows you can use a dynamic disk and then make a spanned volume.
It allows you to use the free storage on many different drives to make a new volume. You can then assign it a drive letter.

As for Ubuntu, I'n not sure, though.

**Dapnoinaacale** · 03-27-2012, 04:03 AM

As for Ubuntu, I'n not sure, though.

in linux its lvm

**Creva4k** · 03-27-2012, 05:29 AM

Have a look at mhddfs. It works at the filesystem level and merges multiple mounted filesystems into one.

I'm using it on my home server. It should do what you're after without having to reformat anything. It's even in the Ubuntu repo.

03-24-2012, 10:03 PM	#1
toreesi Join Date Oct 2005 Posts 595 Senior Member	Two HDDs combined I think there is a small chance I have asked this before, as I have been thinking about it off and on for a while now, but is it possible to convince an OS that two HDDs are in fact one big one? If it is possible, what would the pros and cons be? I am asking now as it has come up again due to me htpc [running ubuntu] has one drive that is nearly full and the other one is only partially used. I am using XBMC to watch and listen to things and I can easily add another source but that only works well in library mode. When not in library mode you have to navigate folders and having two folders for movies would be a pain when trying to locate things. Alternatively, I might try in putting some of my movie folders on the other drive but link to them from the previous place and see if XBMC is happy with that. I know some programs are happy to accept a short cut as a folder... Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-24-2012, 11:40 PM	#2
Relsenlilky Join Date Oct 2005 Posts 465 Senior Member	JBOD or RAID. Lots of information if you search for those. Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-24-2012, 11:49 PM	#3
igs00r Join Date Oct 2005 Posts 601 Senior Member	http://www.davelachapelle.ca/guides/ubuntu-lvm-guide/ Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-25-2012, 01:09 AM	#4
toreesi Join Date Oct 2005 Posts 595 Senior Member	RAID doesn't seem to have anything that does it, or if it does, its tech speak is a little beyond me at this point in time. JBOD seems ambiguous as it appears to represent two completely different things. However, JBOD has brought me closer to concatenation/spanning which I guess is what I am after. However, even though I know the advantages of doing it, I do not not if there are any known disadvantages. I can see that there might be some drama at the boundaries but can't be sure of that. Also, would it be possible to combine concatenation and raid? Like if I had 2 x 1 TB HHDs in one "span" could I RAID them so that they are backed up in another 2 x 1 TB HDDs in a "span"? Edit: Also, when I first saw that "fish slapping maniac" link, I thought it might be to some funny guy going on about drugs or some such...completely missed the "la" part... Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-25-2012, 01:20 AM	#5
QHdy5Z3A Join Date Oct 2005 Posts 393 Senior Member	is it possible to convince an OS that two HDDs are in fact one big one? If it is possible, what would the pros and cons be? Yep, but if one disk dies, you lose all data. Better to buy a new larger HDD & clone the existing one. Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-25-2012, 01:25 AM	#6
toreesi Join Date Oct 2005 Posts 595 Senior Member	Yep, but if one disk dies, you lose all data. Better to buy a new larger HDD & clone the existing one. GrumbleGrumble* The problem with computing these days, everything always needs updating! Eventually when finances are right I'll finally build that NAS... Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-25-2012, 03:14 AM	#7
Dapnoinaacale Join Date Oct 2005 Posts 465 Senior Member	lvm will do the same. but personally i would just mount thec2 volumes on the nas. Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-25-2012, 07:19 PM	#8
excivaamome Join Date Nov 2005 Posts 381 Senior Member	Raid can be used to make 2 hard drives appear as a single drive. Using a RAID 0 set, data is divided into discrete blocks and written to each drive in an alternating fashion (called striping), i.e. block 1 to drive 1, block 2 to drive 2, block 3 to drive 1. When using 2 drives this makes a raid volume that is twice the size of the smallest physical drive, and as the data is striped across both drives the read/write performance is almost doubled. The flaws to this approach are that the resultant raid volume has double the chance of catastrophic failure, as a failure in either physical drive will result in the loss of ALL data. Additionally, you would need to copy all of the data off the drives before creating a raid volume, as all data on the drives is lost when the volume is initially created. There is some good info on the Wikipedia page about raid. I would personally recommend against a RAID 0 set, unless you maintain a regular backup of the data. http://en.wikipedia.org/wiki/RAID Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-26-2012, 03:58 AM	#9
Drugmachine Join Date Apr 2006 Posts 4,490 Senior Member	In Windows you can use a dynamic disk and then make a spanned volume. It allows you to use the free storage on many different drives to make a new volume. You can then assign it a drive letter. As for Ubuntu, I'n not sure, though. Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-27-2012, 04:03 AM	#10
Dapnoinaacale Join Date Oct 2005 Posts 465 Senior Member	As for Ubuntu, I'n not sure, though. in linux its lvm Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

03-27-2012, 05:29 AM	#11
Creva4k Join Date Oct 2005 Posts 382 Senior Member	Have a look at mhddfs. It works at the filesystem level and merges multiple mounted filesystems into one. I'm using it on my home server. It should do what you're after without having to reformat anything. It's even in the Ubuntu repo. Share Share this post on Digg Del.icio.us Technorati Twitter
	Quote

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