* Overlay ramdisk on filesystem?
@ 2004-04-15 21:08 Timothy Miller
2004-04-15 21:13 ` Florian Weimer
2004-04-16 19:38 ` Erik Tews
0 siblings, 2 replies; 3+ messages in thread
From: Timothy Miller @ 2004-04-15 21:08 UTC (permalink / raw)
To: Linux Kernel Mailing List
I have a feeling that this may be a bit too off-topic, but I'm doing
some Linux and hardware performance tests, and some of the tests will
put the hardware into an unstable state which could get memory errors
which could cause filesystem corruption.
I would like to know how I could overlay a RAM disk over a read-only
filesystem so that all new files and modified files end up in the RAM
disk, but old files are read from the disk. This way, when I reboot,
the disk reverts back.
Suggestions?
Thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Overlay ramdisk on filesystem?
2004-04-15 21:08 Overlay ramdisk on filesystem? Timothy Miller
@ 2004-04-15 21:13 ` Florian Weimer
2004-04-16 19:38 ` Erik Tews
1 sibling, 0 replies; 3+ messages in thread
From: Florian Weimer @ 2004-04-15 21:13 UTC (permalink / raw)
To: Timothy Miller; +Cc: Linux Kernel Mailing List
Timothy Miller <miller@techsource.com> writes:
> I have a feeling that this may be a bit too off-topic, but I'm doing
> some Linux and hardware performance tests, and some of the tests will
> put the hardware into an unstable state which could get memory errors
> which could cause filesystem corruption.
In the presence of memory errors, all bets are off anyway.
> I would like to know how I could overlay a RAM disk over a read-only
> filesystem so that all new files and modified files end up in the RAM
> disk, but old files are read from the disk. This way, when I reboot,
> the disk reverts back.
You might have to tweak the underlying file system, too. IIRC, ext2
avoids to reallocate freshly deallocated blocks, to prevent
fragmentation. This will waste a lot of RAM on the long run.
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Overlay ramdisk on filesystem?
2004-04-15 21:08 Overlay ramdisk on filesystem? Timothy Miller
2004-04-15 21:13 ` Florian Weimer
@ 2004-04-16 19:38 ` Erik Tews
1 sibling, 0 replies; 3+ messages in thread
From: Erik Tews @ 2004-04-16 19:38 UTC (permalink / raw)
To: Timothy Miller; +Cc: Linux Kernel Mailing List
Am Do, den 15.04.2004 schrieb Timothy Miller um 23:08:
> I have a feeling that this may be a bit too off-topic, but I'm doing
> some Linux and hardware performance tests, and some of the tests will
> put the hardware into an unstable state which could get memory errors
> which could cause filesystem corruption.
>
> I would like to know how I could overlay a RAM disk over a read-only
> filesystem so that all new files and modified files end up in the RAM
> disk, but old files are read from the disk. This way, when I reboot,
> the disk reverts back.
This could be possible using a ramdisk, a filesystem on a disk (which
could be a read only block device like a cdrom too), device-mapper and
its snapshot-target. But I did not try yet.
^ permalink raw reply [flat|nested] 3+ messages in thread
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