Too many disks in system? (RAID5)

Too many disks in system? (RAID5)

[Lukas Hejtmanek]

Hello,

I have system with attached SATA array which contains 24 disks. I wanted to run
software RAID 5, but 24 disks means, that I would need /dev/sda to /dev/sdx
devices with major 8 and last minor 384. Minor seems to be limited to 8 bits.
Is there any chance to run software array using all 24 disks?

My test was with mknod v. 5.2.1 and kernel 2.6.14.3

-- 
Lukáš Hejtmánek

Re: Too many disks in system? (RAID5)

[Lennart Sorensen]

On Mon, Nov 28, 2005 at 11:25:58PM +0100, Lukas Hejtmanek wrote:
> Hello,
> 
> I have system with attached SATA array which contains 24 disks. I wanted to run
> software RAID 5, but 24 disks means, that I would need /dev/sda to /dev/sdx
> devices with major 8 and last minor 384. Minor seems to be limited to 8 bits.
> Is there any chance to run software array using all 24 disks?
> 
> My test was with mknod v. 5.2.1 and kernel 2.6.14.3

Major 8 is not the only scsi major.  Look at devices.txt in the kernel
Documentation dir.  MAKEDEV also usually knows how to make more scsi
devices.  For example major 65.  Just use MAKEDEV /dev/sdx and see what
it creates.

Len Sorensen

Re: Too many disks in system? (RAID5)

[Bill Davidsen]

Lennart Sorensen wrote:
> On Mon, Nov 28, 2005 at 11:25:58PM +0100, Lukas Hejtmanek wrote:
> 
>>Hello,
>>
>>I have system with attached SATA array which contains 24 disks. I wanted to run
>>software RAID 5, but 24 disks means, that I would need /dev/sda to /dev/sdx
>>devices with major 8 and last minor 384. Minor seems to be limited to 8 bits.
>>Is there any chance to run software array using all 24 disks?
>>
>>My test was with mknod v. 5.2.1 and kernel 2.6.14.3
> 
> 
> Major 8 is not the only scsi major.  Look at devices.txt in the kernel
> Documentation dir.  MAKEDEV also usually knows how to make more scsi
> devices.  For example major 65.  Just use MAKEDEV /dev/sdx and see what
> it creates.

Does udev not know how to handle this?
-- 
    -bill davidsen (davidsen@tmr.com)
"The secret to procrastination is to put things off until the
  last possible moment - but no longer"  -me

Re: Too many disks in system? (RAID5)

[Lennart Sorensen]

On Tue, Nov 29, 2005 at 02:22:35PM -0500, Bill Davidsen wrote:
> Does udev not know how to handle this?

Some people might not run udev.  I certainly don't.

When udev stops occationally breaking old kernels while requiring a new
version for a new kernel, then I will consider using it.  That might be
a while.

Len Sorensen

Re: Too many disks in system? (RAID5)

[Tomasz Torcz]

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On Tue, Nov 29, 2005 at 05:01:21PM -0500, Lennart Sorensen wrote:
> On Tue, Nov 29, 2005 at 02:22:35PM -0500, Bill Davidsen wrote:
> > Does udev not know how to handle this?
> 
> Some people might not run udev.  I certainly don't.
> 
> When udev stops occationally breaking old kernels while requiring a new
> version for a new kernel, then I will consider using it.  That might be
> a while.

 udev requirements tend to be overstated. I run 2.6.15-rc3 with udev-064
and everything works fine.

-- 
Tomasz Torcz               RIP is irrevelant. Spoofing is futile.
zdzichu@irc.-nie.spam-.pl     Your routes will be aggreggated. -- Alex Yuriev


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Re: Too many disks in system? (RAID5)

[Lennart Sorensen]

On Wed, Nov 30, 2005 at 04:34:51PM +0100, Tomasz Torcz wrote:
>  udev requirements tend to be overstated. I run 2.6.15-rc3 with udev-064
> and everything works fine.

Perhaps udev is just overrated. :)  Maybe if I used usb devices a lot I
would find it useful or something.

Len Sorensen

Re: Too many disks in system? (RAID5)

[Bill Davidsen]

Lennart Sorensen wrote:
> On Wed, Nov 30, 2005 at 04:34:51PM +0100, Tomasz Torcz wrote:
> 
>> udev requirements tend to be overstated. I run 2.6.15-rc3 with udev-064
>>and everything works fine.
> 
> 
> Perhaps udev is just overrated. :)  Maybe if I used usb devices a lot I
> would find it useful or something.

Actually, keeping /dev clean is a reason. I haven't added it to existing 
machines with distros no uning udev, I use it on machines which come 
with it.

-- 
bill davidsen <davidsen@tmr.com>
   CTO TMR Associates, Inc
   Doing interesting things with small computers since 1979