According to Wikipedia a normal 3.5" harddisk is 25.4mm high, but then there exist also a 19mm version, which I need for a HP ProLiant MicroServer.

Looking at our resellers webshop I see the following options

  • 1/3H
  • SlimLine
  • 1/2H
  • 1/4H
  • LFF

When I search for the model number VB0250EAVER on the disk that just broke, some webshops call it for LFF, which should be Large Form Factor, which I find weird, as it is smaller than a normal 3.5".


Does anyone know for sure what the 19mm model is called?

  • What model is the server? HP's website has a compatibility list. LFF is a 3.5" drive or "desktop" drive, and 2.5" are laptop drives. See this for a reference. – Nathan C Sep 27 '13 at 14:19
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    I have two microservers and as they use the (very cheap and plasticy) HP drive trays I added extra disks to my machines without issues. I didn't actually look at the disk provided with the machine and compare it to those I put in. – tombull89 Sep 27 '13 at 14:33
  • Are you going to use ZFS on these? – ewwhite Sep 27 '13 at 14:35
  • @ewwhite Yes, that is my intention for use it for ZFS. It sounds like there is something I should know? =) – Sandra Sep 27 '13 at 15:15
  • @Sandra See the list I posted in my answer. It included some information on which disks are ZFS-friendly. – ewwhite Sep 27 '13 at 15:37

The term for this type of disk is a slimline 20mm disk. The OEM for the HP drive you've mentioned is the Seagate ST3250318AS

The Microserver uses it's own special drive trays/carriers. You can use any 3.5" disk in the enclosure, though.

Here's a list of community-submitted compatible drives.

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    Leave it to the resident HP guru. :P – Nathan C Sep 27 '13 at 14:22

For a long time I have used a couple of Maxtor Diamondmax plus 8 low-height 40G drives. They were marketed as 2/3 height, lighter and have improved airflow for cooling. True to form this drive model is slightly slimmer than 19mm as it measures just under 17mm.

If you can find spare replacement and the 2.5" option is available, then choose the latter as the additional benefits of extra cooling space and lower power consumption will help improve overall reliability.

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    Do you have anything to backup your assertion that "extra cooling space" improves reliability? Google's study, which included hundreds of thousands of drives, suggests otherwise. Not all 2.5" drives consume less power than 3.5" drives either, perhaps you could be more specific as to how a 2.5" drive would be more reliable because of it's power consumption patterns. – Chris S Oct 8 '13 at 13:20

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