LinuxQuestions.org
Help answer threads with 0 replies.
Go Back   LinuxQuestions.org > Forums > Linux Forums > Linux - Hardware
User Name
Password
Linux - Hardware This forum is for Hardware issues.
Having trouble installing a piece of hardware? Want to know if that peripheral is compatible with Linux?

Notices

Reply
 
LinkBack Search this Thread
Old 08-18-2004, 07:56 AM   #1
Spyder_doo
LQ Newbie
 
Registered: Aug 2004
Posts: 3

Rep: Reputation: 0
maximum number of Hard drives


I was just wondering how many hard drives you can put in a single backup server running Fedora 2?

Thanks,
Jamie
 
Old 08-18-2004, 08:18 AM   #2
rjlee
Senior Member
 
Registered: Jul 2004
Distribution: Ubuntu 7.04
Posts: 1,990

Rep: Reputation: 65
Linux does not put arbitrary limits on the number of hard disks.

With IDE, ATAPI, ATA or SATA drives, you are limited to two disks per channel (master and slave), and usually two channels per controller. But you can still install extra controllers as expansion cards.

With SCSI drives, you can daisy-chain more devices on a single controller (Googling for this, I think 6 might be the typical limit, but you may be able to get more than that on some controllers). Again, you can get additional controllers.

With USB, you can attach as many devices as you like, up to a few hundred per controller given enough powered hubs. Again, you can buy more controllers if you like, but note that the bandwidth is split between all the disks on one controller (and USB hard disks don't tend to have a good size*speed/price ratio).

Inside the kernel, the settings for each device are stored as a vector of device nodes (If I remember rightly), so you even can have as many devices as you like running from the same driver inside the kernel.

In practice, the limits are likely to be the cooling power of your computer (I'd recommend hard-disk coolers if you're running many drives, especially in a smaller box), and the limits of your computer's power supply.

To put more than a few dozen drives in a single box, you may also need to create more nodes in the /dev/ filesystem before Fedora will see them. Alternatively, you could use a hardware RAID controller to combine them into a single device.

You can also have as many software RAID partitions as you like.

Hope that helps,

— Robert J. Lee
 
Old 08-18-2004, 08:09 PM   #3
Spyder_doo
LQ Newbie
 
Registered: Aug 2004
Posts: 3

Original Poster
Rep: Reputation: 0
Hard drives

So I can put as many usb drives as I want on my server right?

Thanks,
Jamie
 
Old 08-19-2004, 01:05 AM   #4
mritch
Member
 
Registered: Nov 2003
Location: austria
Distribution: debian
Posts: 667

Rep: Reputation: 30
i think there is a limit of 128 devices with usb v1 (don't know about v2).
sure you'll get bandwidth problems with a lot of drives.

sl mritch.
 
Old 08-19-2004, 03:26 AM   #5
rjlee
Senior Member
 
Registered: Jul 2004
Distribution: Ubuntu 7.04
Posts: 1,990

Rep: Reputation: 65
Also, note that devices include the number of hubs (and the host controller as well, I think). Hubs only tend to go up to eight or so devices. USB v.2 is faster (possibly comparable to ATAPI with one device at a guess, and 1/n of that speed with n drives)

If you want lots of storage space, you're probably better off looking at SCSI (or ATAPI if money is also an issue).

You could also look at setting up disk partitions if you just want to see a large numbers of small “drives” in software. (By the way, you can use software-raid on partitions as well as physical drives).
 
Old 08-19-2004, 02:46 PM   #6
Spyder_doo
LQ Newbie
 
Registered: Aug 2004
Posts: 3

Original Poster
Rep: Reputation: 0
hard drives

Well, we now have 25+ hard drives on one machine and are continuing to add more. We are trying to set up a nightly back up for every employee that we have here on their own 120 Gig hard drive. So far so good, let me know of anymore information that might be useful to me.

Thanks,
Jamie
 
  


Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
maximum number of dots in a domain name unix20009876 Linux - Software 2 11-17-2005 12:53 PM
Maximum number of contacts in GAIM duffmckagan Linux - Software 7 08-01-2005 01:02 PM
Number of hard disks/drives info? mali Linux - Enterprise 3 01-10-2005 03:59 PM
maximum number of HDs gr00ve Linux - Hardware 2 09-05-2004 06:43 AM
number of hard drives on a network sadiboyz Linux - Software 0 08-11-2003 04:46 AM


All times are GMT -5. The time now is 06:34 PM.

Main Menu
My LQ
Write for LQ
LinuxQuestions.org is looking for people interested in writing Editorials, Articles, Reviews, and more. If you'd like to contribute content, let us know.
Main Menu
Syndicate
RSS1  Latest Threads
RSS1  LQ News
Twitter: @linuxquestions
identi.ca: @linuxquestions
Facebook: linuxquestions Google+: linuxquestions
Open Source Consulting | Domain Registration