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Hi all, On a testing cluster, I upgraded from Firefly to Giant. Without changing anything, read performance on a RBD volume (in a VM) has been divided by 4 ! With Firefly, in the VM (/dev/vda is a Virtio RBD device) : hdparm -Tt /dev/vda /dev/vda: Timing cached reads: 20568 MB in 1.99 seconds = 10314.48 MB/sec Timing buffered disk reads: 1190 MB in 3.00 seconds = 396.49 MB/sec With Giant : hdparm -Tt /dev/vda /dev/vda: Timing cached reads: 20340 MB in 1.99 seconds = 10199.48 MB/sec Timing buffered disk reads: 318 MB in 3.00 seconds = 105.85 MB/sec Write performance is the same than before, no change. How can we explain this ? Every system is running Debian Wheezy. Thank you a lot. |
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