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I usually pre-allocate whole disk space when creating my VMs and usually as flat single files. Since I'd like to move my VMDK to a different drive than my primary I would like to put it on one that has best performance of particular read/write disk IO type.
Question
What is typical disk operation when working with virtual preallocated flat files? Is it sequential, random 512, 4k? Anything else I should know about?
The thing is I've bought a very fast SDHC (SanDisk UHS-I ExtremePro with advertised 95MB/s read speed) card and I'd like to put my VM on it.
When I run CrystalDiskMark it reports these results:
MB/s MB/s
------------------
Seq: 7.7 7.4
512: 7.7 3.8
4k: 3.9 1.3
4k QD32: 3.9 1.3
Especially the 4k speeds are higher than my USB2 attached 7200 platter disk.
Robert Koritnik
Posted 2014-05-23T12:52:17.343
Reputation: 1 728
If they are higher then your 7200 platter disks whats the problem? – Ramhound – 2014-05-23T16:18:01.683
@Ramhound the 4k are higher but others aren't. Hence my question... – Robert Koritnik – 2014-05-23T17:02:04.153
The table isn't even clear. You told us nothing about which specific products you have. Clarify the table and provide the product information. – Ramhound – 2014-05-23T17:25:12.460
@Ramhound: Isn't clear? it displays disk read/write performance in MB/s for each individual type of IO work operations. If you'd run CrystalDiskMark you'd see what these mean. Seq means sequential reads/writes of a long file, then we have 512k sizes and 4k... WHat else should be cleared about table data? These info is related to aforementioned SDHC card... – Robert Koritnik – 2014-05-26T15:43:30.977
If it was clear I wouldn't have asked. I understand what the table say just not sure which column is what. – Ramhound – 2014-05-26T15:48:47.090