Hopefully someone have the answer or some advice to get better performance with VMware View Linked Clone VM. I'm just trying to figure out why disk performance is so slow with Linked Clone disk if compare with normal disk. Just compare the two simples tests done with Iometer with the same config (4K, 80% write, 100% random). The first test is inside the Linked Clone disk (C:\) and the second one is through normal disk added to the same VM on the same datastore.
RESULTS with C:\ (Linked Clone)
iops: 376
Throughput: 1,6MBps
Latency: 25ms
CPU: 62%
RESULTS with D:\ (normal disk added on the same datastore - Thin Provisionning)
iops: 3369
Throughput: 13,8MBps
Latency: 3,0ms
CPU: 13,5%
The latency is almost 10 times longer and the IOPS is almost 10 times less with Linked Clone disk. I have attached the Iometer results here combine with the ESXTOP results. The ESXTOP shows the same poor results but strangely the VM do a lot of reads with the Linked Clone test. The CBRC is activated on this pool but I'm not thinking it could have an effect since the Iometer disk is on the "delta" so not in the digest disk.
I'm pretty sure the problem is not with hardware but just in case, here the setup:
ESXi 5.5 (Dell Poweredge R620)
Equallogic PS6100XV
4 X iSCSI 1Gbs paths
View Horizon 5.3.1
vCenter 5.5
Windows 7 x64 base image, 2 vcpu