Disable read/write caching to disk?
Eric Anderson
anderson at centtech.com
Thu May 26 11:07:33 PDT 2005
Bjoern Koenig wrote:
> Eric Anderson wrote:
>
>> Bjoern Koenig wrote:
>>
>> Thanks.. I've just read (quickly) both man pages. It seems as though
>> you are suggesting disabling the physical disk caching, which should
>> not make a difference in my case. The disk would report whatever it
>> needs to report to either host, and those should be in sync.
>
>
> Oh, I'm sorry. I have misunderstood you then.
>
>> When I mount the filesystem on host B ro, it shows me the filesystem
>> as of the time that I mounted it ro. Any subsequent changes on host A
>> (which has it mounted rw) are not seem on host B unless I unmount and
>> mount again on host B. This seems like a FreeBSD feature and not a
>> general scsi feature.
>
>
> By what mechanism do you mount the partitions remote? I'm not very
> experienced with this. I'm thinking of a typical network file system or
> GEOM gate.
I have two servers connected directly to a fiber channel disk array
(containing 16 WD Raptor SATA drives in RAID0+1 configuration). Each
server sees the same exact luns, so I create the partition and
filesystem from host A. I mount it (rw) on host A. Then, if I do a:
camcontrol rescan all
on host B, I pick up the fiber channel disk and it sees it as da0 (just
like on host A). I can then mount it rw or ro on host B.
I think using GEOM gate might give a similar situation.
Eric
--
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Eric Anderson Sr. Systems Administrator Centaur Technology
A lost ounce of gold may be found, a lost moment of time never.
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