SATA - SCSI Partition limit

SATA - SCSI Partition limit

[John Duthie]

Problem:
     Need to simulate CDs shares on a linux/samba File server... has a
120 GB SATA drive in there ...

( linux-2.6.10 ) 

long story ...
      Shares had the wrong size for the evil VB program 
     (Tried mounting *.iso via loopbak - it didn't like it )
     Windows boxes that work just have lots of 700 mb partitions  ( 4
x extended with 6 or 7 logical in each )
     SO i thought "I know I'll just make lots of partitions"  oops ,
SCSI sub system only allows 15 Drives
  So now I could "Boot 2.6.11ac7 on it and specify the boot option
"all-generic-ide" " which worked wonders last time i had a problem
(Thanks Alan) because ide will allow more than 15 partitions.
  But the machine is now about 500 km away from me and changing a
linux system to boot from scsi to ide over ssh is not my idea of fun,
1 typo and I've got a long drive ahead :-(,
  are there any hard reasions for the 15 partition limit on scsi (
other than lots of dev files )

  how much work would a patch to halve the number of /dev/sd? files
and double the /dev/sd?[12]? files ( same number of devices
minor/major ) ?

I'm sure this will be a problem more people have as the SATA drives
get bigger.......

TIA

Re: SATA - SCSI Partition limit

[Grzegorz Kulewski]

On Wed, 15 Jun 2005, John Duthie wrote:

> Problem:
>     Need to simulate CDs shares on a linux/samba File server... has a
> 120 GB SATA drive in there ...
>
> ( linux-2.6.10 )
>
> long story ...
>      Shares had the wrong size for the evil VB program
>     (Tried mounting *.iso via loopbak - it didn't like it )
>     Windows boxes that work just have lots of 700 mb partitions  ( 4
> x extended with 6 or 7 logical in each )
>     SO i thought "I know I'll just make lots of partitions"  oops ,
> SCSI sub system only allows 15 Drives
>  So now I could "Boot 2.6.11ac7 on it and specify the boot option
> "all-generic-ide" " which worked wonders last time i had a problem
> (Thanks Alan) because ide will allow more than 15 partitions.
>  But the machine is now about 500 km away from me and changing a
> linux system to boot from scsi to ide over ssh is not my idea of fun,
> 1 typo and I've got a long drive ahead :-(,
>  are there any hard reasions for the 15 partition limit on scsi (
> other than lots of dev files )
>
>  how much work would a patch to halve the number of /dev/sd? files
> and double the /dev/sd?[12]? files ( same number of devices
> minor/major ) ?
>
> I'm sure this will be a problem more people have as the SATA drives
> get bigger.......

Use device-mapper or some tool that uses it (evms). You will be able to 
have really big amount of partitions on SCSI or SATA drive. I used about 
30 partitions once. You make them normally with fdisk and then at boot 
evms will take care of them. Just remember to use /dev/evms/sdaxx instead 
of /dev/sdaxx.


Grzegorz Kulewski

Re: SATA - SCSI Partition limit

[Måns Rullgård]

John Duthie <beyondgeek@gmail.com> writes:

> Problem:
>      Need to simulate CDs shares on a linux/samba File server... has a
> 120 GB SATA drive in there ...
>
> ( linux-2.6.10 ) 
>
> long story ...
>       Shares had the wrong size for the evil VB program 
>      (Tried mounting *.iso via loopbak - it didn't like it )
>      Windows boxes that work just have lots of 700 mb partitions  ( 4
> x extended with 6 or 7 logical in each )
>      SO i thought "I know I'll just make lots of partitions"  oops ,
> SCSI sub system only allows 15 Drives

Use LVM.

-- 
Måns Rullgård
mru@inprovide.com