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<html><head><title>Re: [Beowulf] Should I go for diskless or not?</title>
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<p>Hallo Dr,</p>
<p><br></p>
<p>Mittwoch, 13. Mai 2009, meintest Du:</p>
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<p><span class=rvts6>I have a cluster of identical computers. We are planning to add more nodes later. I was thinking whether I should go the diskless nodes way or not? Diskless nodes seems as a really exciting, interesting and good option, however when I did it I needed to troubleshoot a lot. I did fix it up, but I had to redo the filesystem, but the past experiences didn't make much of a difference. I still need to fix up everything, I kinda need your help to decide.</span></p>
<p><span class=rvts6>Also, performance wise, I was thinking that diskless is not a good option, and since performance matters . . .</span></p>
<p><span class=rvts6>Can somebody outline the pros and cons of each or just give me thier opinion.</span></p>
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<p>Local disk allows you to have </p>
<p> - local cached version of the OS-Image (could lead to faster bootup - depends on the image size)</p>
<p> - local swap - can be used to suspend jobs and free the memory they are using by swapping it to disk. A newly started high-prio-job can then be started</p>
<p> - local scratch - might be useful for some jobs</p>
<p> - saves memory because you don't have to put some OS-image into RAM</p>
<p> - avoids network trafic (no NFS-Root, no /usr-mounts over NFS or such stuff... )</p>
<p><br></p>
<p>Local disk cons:</p>
<p> - it is a piece of hardware that can fail (might matter if you have a big number of nodes/disks)</p>
<p> - it costs money</p>
<p><br></p>
<p>I saw lately that a customer was using a Lustre-Filesystem for scratching (no big news, can be much faster than local disks) and to put swap-files on it. Might be a good compromise - but just if you have a lustre-environment anyway. </p>
<p><br></p>
<p>Jan </p>
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