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Re: [Xen-API] Only 309 MB of RAM is showing out of 4GB

Hi Ananthan,

                          Thank you very much for replying,
some details:
System with 4GB ram is our test environment,our server is 48 GB but

ok, that sounds more appropriate :-)

comes with a single hdd,but need to run 7 vms on it.So i believe sharing
a single hdd among 7 vms and host machine simply adds disk i/o and can
cause serious bottlenecks

io is definitly the main bottleneck for common workload in virtualisation.

,to avoid that i thought of running vm on
/dev/shm and take regular backups.i dont know whether i can do this with
XCP,but i have done it with XEN by moving *.img* file to /dev/shm and
starting vm from there. Once again thanks alot.

if you don't want to invest in a good raid card with bbu (Areca rocks), you can still create a software raid with linux md and have decent performace.

Software Raid cannot be setup at install time, but if you can add after first install (you first create the /dev/md0 with a few disks, and then define a storage repository on top). It not fully safe since there is no bbu and it does not deactivate hdd cache, but it should fine if you have manageable ups.

one more thing:
I believe your suggestion for memory is also applicable to hardisk
also.since df -h is showing around 4 Gb.

XCP creates a 4GiB partition for dom0 system, then an empty 4GiB partition (remnant of xenserver), and then create a big LVM partition (standard install), or a ext3 partition (if you chose thin provisioning during install), so extra disk space is just around the corner.



PS : don't forget to respond to the mailing list

Thanking You,

On Mon, Aug 13, 2012 at 5:43 PM, Denis Cardon
<mailto:denis.cardon@xxxxxxxxxxxxxxxxxxxxxx>> wrote:

    Hi Ananthan,

                                 Thank you very much for clarifying my
        concern.But what i really want was to run all the Virtual Machine on
        shared memory /dev/shm (tmpfs).i have done it using xen by copying
        virtual image .img files to /dev/shm and started from there.But for
        doing that when i checked memory status i found this thing.is
        <http://thing.is> there a way to make the VM run on /dev/shm
        rather on
        HDD,to avoid i/o wait.

    you can increase the RAM of dom0 by changing the dom0_mem value in
    extlinux.conf and restarting your XCP server. However 4GiB is not a
    lot of ram and you won't have much room for putting both vm content
    and ram...

    Afterward, you will have to create a storage repository (xe
    sr-create) on /dev/shm to store your vdi there. I don't know if it
    works out of the box on ramdisk.



    PS : please, try to answer on the mailing list.

        On Mon, Aug 13, 2012 at 2:02 PM, Denis Cardon
        <mailto:denis.cardon@xxxxxxxxxxxxxxxxxxxxxx>>> wrote:

             Hi Ananthan,

                       installed XCP 1.1 on intel i5 second gen
        processor  with 4
                 GB RAM
                 but *top,free -m,cat /proc/meminfo* is showing only 309
        mb of
                 RAM space....

                       How can it be fixed..

             dom0 memory is constrained by parameters in the extlinux
        boot param
             in/boot/extlinux.conf (look for the dom0_mem). Here in my
        conf below
             it is set to  752Mo, and it may vary after installation
        depending on
             the whole RAM of the server.

             cat /boot/extlinux.conf

             label xe
                # XCP
                kernel mboot.c32
                append /boot/xen.gz dom0_mem=752M lowmem_emergency_pool=1M
             crashkernel=64M@32M console= vga=mode-0x0311 ---
             /boot/vmlinuz-2.6-xen root=LABEL=root-nddcwqei ro xencons=hvc
             console=hvc0 console=tty0 quiet vga=785 splash ---

             RAM used by dom0 is not available for virtual machines, it
        is used
             for network bridging and physical block device handling, etc.

             So it means that you have 4GiB - 300MiB of RAM available
        for your
             virtual machines.



                 *ouput from xsconsole *

                 *System Memory*

                    Total memory                       4096 MB
                    Populated memory sockets   2
                    Total memory sockets           4
                 BIOS Information
                 Version      BLH6710H.86A.0119.2011.0523.____1030

                 Vendor       Intel Corp

                 *Processor Details*

                     Logical CPUs                       4
                     Populated CPU Sockets        1
                     Total CPU Sockets               1

                 x Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz

                 *free -m*

                           total       used       free     shared    buffers
                 Mem:           309        284         24          0
                 -/+ buffers/cache:        161        147
                 Swap:          511          0        511


                 Mem:    316416k total,   291956k used,    24460k free,
                 Swap:   524280k total,        0k used,   524280k free,

                 *cat /proc/meminfo*

                 MemTotal:           316416 kB
                 MemFree:           24616 kB
                 Buffers:               6584 kB
                 Cached:              119072 kB
                 SwapCached:            0 kB
                 Active:                64236 kB
                 Inactive:             100496 kB
                 Active(anon):      38888 kB
                 Inactive(anon):     5024 kB
                 Active(file):      25348 kB
                 Inactive(file):    95472 kB
                 Unevictable:        6436 kB
                 Mlocked:            6436 kB
                 HighTotal:             0 kB
                 HighFree:              0 kB
                 LowTotal:         316416 kB
                 LowFree:           24616 kB
                 SwapTotal:        524280 kB
                 SwapFree:         524280 kB
                 Dirty:               532 kB
                 Writeback:             0 kB
                 AnonPages:         45544 kB
                 Mapped:            18040 kB
                 Shmem:               132 kB
                 Slab:              18636 kB
                 SReclaimable:       9612 kB
                 SUnreclaim:         9024 kB
                 KernelStack:        1520 kB
                 PageTables:            0 kB
                 NFS_Unstable:          0 kB
                 Bounce:                0 kB
                 WritebackTmp:          0 kB
                 CommitLimit:      682488 kB
                 Committed_AS:     660896 kB
                 VmallocTotal:     245752 kB
                 VmallocUsed:        4576 kB
                 VmallocChunk:     237148 kB
                 DirectMap4k:      754492 kB
                 DirectMap2M:           0 kB


                 This body part will be downloaded on demand.

             Denis Cardon
             Tranquil IT Systems
             44 bvd des pas enchantés
             44230 Saint Sébastien sur Loire
             tel : +33 (0)

    Denis Cardon
    Tranquil IT Systems
    44 bvd des pas enchantés
    44230 Saint Sébastien sur Loire
    tel : +33 (0) <tel:%2B33%20%280%29%>
    http://www.tranquil-it-__systems.fr <http://www.tranquil-it-systems.fr>

Denis Cardon
Tranquil IT Systems
44 bvd des pas enchantés
44230 Saint Sébastien sur Loire
tel : +33 (0)

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