Thanks everyone for the great INFO... This was EXACTLY what I needed and
had a very hard time finding out. The mount -t tmpfs -o size=1g none
/ramdisk worked perfectly. I needed temporary ram space to use as disk
space. Thanks!
Just to explain further, the "images" are not ISO's... These are hard
drive images, like GHOST files (only using a Linux free application).
But to further explain, even if I mounted an ISO, there would still be
disk IO.. I'm trying to eliminate the disk I/O from the equation so I
can be downloading 20 or 25 machines at the same time. Since the server
us a dual 2.0gig Xeon and I have gig all the way from the server to the
desktop.. This should scream!
Thanks again.
Scott
-----Original Message-----
From: centos-bounces@xxxxxxxxxx [mailto:centos-bounces@xxxxxxxxxx] On
Behalf Of Craig White
Sent: Thursday, March 31, 2005 10:38 AM
To: centos@xxxxxxxxxx
Subject: Re: Odd Question... MAX Ram Disk Size
On Thu, 2005-03-31 at 09:59 -0600, Aleksandar Milivojevic wrote:
> Scott Heisler wrote:
> > I want to put that image file on a RAMDISK on my server.
> > The image file is between 3 and 4 gig. I have 6 gig in the server,
> > so plenty of memory. I modified GRUB to increase the size of my ram
> > disk... First I started with a 200mb, that worked group, formatted,
etc.
> > Then I tried 1gig - everything looks like it works but when I mount
> > it, it tells me the volume is not formatted or has invalid super
blocks.
> > Perhaps I'm exceeding the allowable built-in ramdisk limit, but I
> > couldn't find any docs anywhere that would tell me what that limit
was.
>
> When you say ramdisk, do you mean ramdisk as in ramsdisk device
> (hardware) that keeps information accross system reboots and/or power
> cycles, or ramdisk as in file system that exists only in your server's
> RAM and is lost each time machine is rebooted? Not clear from your
> question. You mention having "enough RAM for it in server" (which
> would imply later), but you also say that you are looking for "device"
> (which would imply former).
>
> If you are looking for self-contained device, there are many solid
> state disks (SSD) available on the market. Basically, they look like
> disk, the "only" difference is instead of having magnetic plates, they
> store information into internal RAM (either battery backed up, or of
> the non-volatile type). System sees them as normal IDE/SATA/SCSI/FC
> drive (depending on the interface), and you don't need to have
> anything special to access them. The speed is usually limited by
> interface used and type of memory used (obviously EEPROM based SSD
> will have much worse write times then DRAM with battery backup based
SSD).
>
> If you are looking for solution to use your server's memory as
> temporary RAM disk (you don't care information being lost when you
> reboot or power cycle), something like this works nicely:
>
> # mount -t tmpfs -o size=8g none /ramdisk
>
> That would create 8GB memory-based file system. The memory file
> system uses is swappable. So just make sure free RAM + free swap is
> larger than 8GB, and you should be fine. Of course, you can create
> smaller or larger system too. Basically it is the same thing as tmpfs
> on Solaris systems. I kind of like to mount /tmp this way (of course,
> with much smaller size, usually 32-128MB, depending on server's
needs).
>
> Or you can place it in fstab to have it always available:
>
> none /ramdisk tmpfs size=8g 0 0
----
this is great info and I suppose I might find use for it someday but
wouldn't a loop mount from an iso file (the disk image) be better for
this purpose?
Craig
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