Disc caching problems with shared SCSI disc

Disc caching problems with shared SCSI disc

Post by Ben Dook » Mon, 17 Aug 1998 04:00:00



I have a pair of linux boxes connected together on a single
SCSI bus, with a hard disc on the bus. After one writes to
/dev/sda1, the other doesn't seem to pick up the changes,
showing the old information. Is there anyway to disable this
disc caching, or forcing the system to re-synchronise the
disc cache?

System is RedHat 5.1, using a 2.0.34 kernel.


much appreciated due to current workload.
--
Ben

 
 
 

Disc caching problems with shared SCSI disc

Post by Ignac » Wed, 19 Aug 1998 04:00:00


 >I have a pair of linux boxes connected together on a single
 >SCSI bus, with a hard disc on the bus. After one writes to
 >/dev/sda1, the other doesn't seem to pick up the changes,
 >showing the old information. Is there anyway to disable this
 >disc caching, or forcing the system to re-synchronise the
 >disc cache?
 >
 >System is RedHat 5.1, using a 2.0.34 kernel.
 >

 >much appreciated due to current workload.

You might be better off getting a couple of ethernet cards and setting
up NFS between the two machines, using the faster machine as the
server. That way there is only one cache local to the hard drive.



 
 
 

Disc caching problems with shared SCSI disc

Post by C. Abn » Thu, 20 Aug 1998 04:00:00





> >I have a pair of linux boxes connected together on a single
> >SCSI bus, with a hard disc on the bus. After one writes to
> >/dev/sda1, the other doesn't seem to pick up the changes,
> >showing the old information. Is there anyway to disable this
> >disc caching, or forcing the system to re-synchronise the
> >disc cache?

> >System is RedHat 5.1, using a 2.0.34 kernel.


> >much appreciated due to current workload.

> You might be better off getting a couple of ethernet cards and setting
> up NFS between the two machines, using the faster machine as the
> server. That way there is only one cache local to the hard drive.



I think he might prefer the transfer rates, or even the "kewl"-ness
of a SCSI subnet.  I'm pretty fscking jealous myself.  Unfortunately
I can't answer his Q, but:

        ftp://ftp.internic.net/rfc/rfc2143.txt

might give you some answers.  It's entitled:

        IP Encapsulating over the Small Computer Systems Interface.

-C
--
...if we truly desire world domination, we've got to get our LSD into
the corporate elite's conceptual water supply and alter the beast's
consciousness. -ESR                                           C. Abney

 
 
 

Disc caching problems with shared SCSI disc

Post by Ignac » Sun, 23 Aug 1998 04:00:00







 >>
 >> >I have a pair of linux boxes connected together on a single
 >> >SCSI bus, with a hard disc on the bus. After one writes to
 >> >/dev/sda1, the other doesn't seem to pick up the changes,
 >> >showing the old information. Is there anyway to disable this
 >> >disc caching, or forcing the system to re-synchronise the
 >> >disc cache?
 >> >
 >> >System is RedHat 5.1, using a 2.0.34 kernel.
 >> >

 >> >much appreciated due to current workload.
 >>
 >> You might be better off getting a couple of ethernet cards and
setting
 >> up NFS between the two machines, using the faster machine as the
 >> server. That way there is only one cache local to the hard drive.
 >>

 >
 >I think he might prefer the transfer rates, or even the "kewl"-ness
 >of a SCSI subnet.  I'm pretty fscking jealous myself.  Unfortunately
 >I can't answer his Q, but:
 >
 >   ftp://ftp.internic.net/rfc/rfc2143.txt
 >
 >might give you some answers.  It's entitled:
 >
 >   IP Encapsulating over the Small Computer Systems Interface.
 >
 >-C

There's a BIG difference between connecting two computers via SCSI and
connecting two computers on a SCSI network to a hard drive. In the
second situation, the cache problems are practically unavoidable. In
this case what he should probably do is get a third computer on the
SCSI network, hang the drive off of that, and then use NFS. The goal
is to get the cache OUT of the two computers. The way to do that is to
put it INTO either only one OR a third.


 
 
 

Disc caching problems with shared SCSI disc

Post by Ignac » Sun, 23 Aug 1998 04:00:00







 >>
 >> >I have a pair of linux boxes connected together on a single
 >> >SCSI bus, with a hard disc on the bus. After one writes to
 >> >/dev/sda1, the other doesn't seem to pick up the changes,
 >> >showing the old information. Is there anyway to disable this
 >> >disc caching, or forcing the system to re-synchronise the
 >> >disc cache?
 >> >
 >> >System is RedHat 5.1, using a 2.0.34 kernel.
 >> >

 >> >much appreciated due to current workload.
 >>
 >> You might be better off getting a couple of ethernet cards and
setting
 >> up NFS between the two machines, using the faster machine as the
 >> server. That way there is only one cache local to the hard drive.
 >>

 >
 >I think he might prefer the transfer rates, or even the "kewl"-ness
 >of a SCSI subnet.  I'm pretty fscking jealous myself.  Unfortunately
 >I can't answer his Q, but:
 >
 >   ftp://ftp.internic.net/rfc/rfc2143.txt
 >
 >might give you some answers.  It's entitled:
 >
 >   IP Encapsulating over the Small Computer Systems Interface.
 >
 >-C

There's a BIG difference between connecting two computers via SCSI and
connecting two computers on a SCSI network to a hard drive. In the
second situation, the cache problems are practically unavoidable. In
this case what he should probably do is get a third computer on the
SCSI network, hang the drive off of that, and then use NFS. The goal
is to get the cache OUT of the two computers. The way to do that is to
put it INTO either only one OR a third.


 
 
 

1. Problems when adding a second SCSI-disc (with net, with discs)

Hi,

I have some problems when adding a second drive (IBM) to the SCSI
controller in my computer. Afterwards I see the drive, can fdisk it,
format it an so on, but the network card has no longer connection
to the net (you  can't ping a.s.o. to or from the net).

There are also problems with big SCSI-loads (e.g. when
copying a lot from one to the other disc). The system sends some
SCSI error messages and then hangs.

Please can someone tell me if this is a kwown error or if I do
something wrong.

My config:  ACER  900/M11A with
            PPro 200 MHz with 128 MB
            7880 SCSI controller onboard with
                 Seagate 4GB ST34371N   as ID 0 and
                 IBM 4GB     DCAS 34330 as ID 1 and   < problem
                 CDROM       XM-5701TA  as ID 5
            AWE 64 Soundblaster
            Network 3Com 3C900

            Linux RedHat 4.1
            Kernel 2.0.30

Thanx in advance
  Robert

--

! FAW Ulm          |  phone: (++49) 731 501 8616           !
! Helmholtzstr. 16 |  I have not lost my mind,             !
! D - 89081 Ulm    |     it's backed up on tape somewhere. !

2. finding out remote user

3. Example Motif 2.0 code ?

4. Enable write cache on scsi disc drive

5. RPC Probes

6. Force file write delay / Share datafile in a never_swap_out disk / unix RAM disk

7. Please Help with Help

8. Enabling write cache on SCSI disks

9. (VXVM 4.1) Two disk sharing the same disk id

10. SCSI disk prob (linux has disk sping down)

11. 9Gbyte SCSI disc as boot disc with 1106 cylinders

12. Q: SCSI MO disk and extra hard-disk