<div dir="ltr"><div><div>Hi David,<br><br></div>Regarding hdparm:<br><br> 'hdparm' has to be used against SATA/IDE device.<br><br></div><div>--snip--<br> hdparm - get/set SATA/IDE device parameters<br><br> hdparm provides a command line interface to various kernel interfaces supported by the Linux SATA/PATA/SAS "libata" subsystem and the older<br>
IDE driver subsystem. Many newer (2008 and later) USB drive enclosures now also support "SAT" (SCSI-ATA Command Translation) and therefore<br> may also work with hdparm. E.g. recent WD "Passport" models and recent NexStar-3 enclosures. Some options may work correctly only with<br>
the latest kernels.<br><br></div><div>--/snip--<br></div><div><br></div><div> Here in your guest , its 'virtio' disk ( /dev/vd{a,b,c..} which uses 'virtio' bus and virtio-blk is not ATA, so this looks to be an incorrect way of using 'hdparm'. <br>
<br></div><div>More or less, now the virt software allows you to use "virtio-scsi" ( the disk shown inside the guest will be sd{a,b,..}, where most of featureset is respected from scsi protocol point of view.. you may look into that as well. <br>
<br></div><div>--Humble<br></div><div><br><br></div><div><br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Thu, Apr 3, 2014 at 3:35 PM, Dave Christianson <span dir="ltr"><<a href="mailto:davidchristianson3@gmail.com" target="_blank">davidchristianson3@gmail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Good Morning,<div><br></div><div>In my earlier experience invoking a VM using qemu/libgfapi, I reported that it was noticeably faster than the same VM invoked from libvirt using a FUSE mount; however, this was erroneous as the qemu/libgfapi-invoked image was created using 2x the RAM and cpu's...</div>
<div><br></div><div>So, invoking the image using both methods using consistent specs of 2GB RAM and 2 cpu's, I attempted to check drive performance using the following commands:</div><div><br></div><div>(For regular FUSE mount I have the gluster volume mounted at /var/lib/libvirt/images.)</div>
<div><br></div><div>(For libgfapi I specify -disk file=gluster://gfs-00/gfsvol/tester1/img.)</div><div><br></div><div>Using libvirt/FUSE mount:</div><div>[root@tester1 ~]# hdparm -Tt /dev/vda1</div><div>/dev/vda1:</div><div>
Timing cached reads: 11346 MB in 2.00 seconds = 5681.63 MB/sec</div><div> Timing buffered disk reads: 36 MB in 3.05 seconds = 11.80 MB/sec</div><div>[root@tester1 ~]# dd if=/dev/zero of=/tmp/output bs=8k count=10k; rm -f /tmp/output<br>
</div><div>10240+0 records in</div><div>10240+0 records out</div><div>41943040 bytes (42MB) copied, 0.0646241 s, 649 MB/sec</div><div><br></div><div>Using qemu/libgfapi:<br></div><div><div>[root@tester1 ~]# hdparm -Tt /dev/vda1</div>
<div>/dev/vda1:</div><div> Timing cached reads: 11998 MB in 2.00 seconds = 6008.57 MB/sec</div><div> Timing buffered disk reads: 36 MB in 3.03 seconds = 11.89 MB/sec</div><div>[root@tester1 ~]# dd if=/dev/zero of=/tmp/output bs=8k count=10k; rm -f /tmp/output<br>
</div><div>10240+0 records in</div><div>10240+0 records out</div><div>41943040 bytes (42MB) copied, 0.0621412 s, 675 MB/sec</div></div><div><br></div><div>Should I be seeing a bigger difference, or am I doing something wrong? </div>
<div><br></div><div>I'm also curious whether people have found that the performance difference is greater as the size of the gluster cluster scales up.</div><div><br></div><div>Thanks,</div><div>David</div><div><br></div>
</div>
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