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VMWare ESXi 4.1 Scratch partition?


I have a lab-environment with ESXi 5.1-servers, they are installed on USB-drives.

There is a production environment I work with, which has ESX 4.1 servers, these are installed to SSD-drives. However, for config, choice has been made to move ONLY the scratch-partition to a SAN-drive.
Reason = SSD’s would be worn-out due to frequent read-writes.


*is the reason above  a valid reason/reason to move the scratch-partition, also for (my) ESXi 5?
I always understood, you could remove the USB-drive once server has been booted, since everything runs in RAM (never tried it though)?

*if moving scratch-partion is advisable, is there an article + is there performance gain?

Please advise.
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janhoedtAuthor Commented:
Thanks! Somehow contradictory however:

When booting from USB/SD keep in mind that once ESXi is loaded, it runs from memory and there is very little ongoing I/O to the boot device.

Because USB/SD devices are sensitive to high amounts of I/O the installer will not place the scratch partition on a USB/SD device.  Instead, the installer first scans for a local 4GB vfat partition, if it doesn’t find one it will then scan for a local VMFS volume on which to create a scratch directory.  If no local vfat partition or VMFS volume is found, as a last resort the installer will put the scratch partition in “/tmp/scratch” (i.e. put scratch on the local ramdisk).  If this happens it’s a good idea to manually reconfigure the scratch partition after the install.

So, first it says: it runs in memory BUT you should reconfigure the scratch partition to another drive if no local drive is available since it highly used ....
Subhashish LahaCommented:
Hope this clears your doubt

This “scratch partition” is used for storing

- vm-support dumps
- log files
- userworld swapfiles (if enabled).

When using Boot-from-SAN or USB scratch partitions are not automatically created and the above mentioned files will be stored in a RAM disk. This means that after a reboot these files will be gone. Therefore, from an operational point of view it is a good idea to manually specify or script the scratch partition after the installation. You could use a VMFS volume for it and create multiple folders per server to store the respective files.

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