All drives spin when reading a single file?

  • I'm curious how OpenMediaVault manages its software RAID. Does it actually stripe the data in RAID 5 or does it use a simpler solution and simple have a dedicated parity drive? The reason I ask, is that I'm interested in knowing if OMV is smart enough to only have a single disk drive spinning when it accesses a single file, or does it have all drives spinning (which would obviously be necessary if it stripes the data). Software like unRAID, FlexRAID, and SnapRAID all use a single dedicated parity drive and will only have a single drive spinning when accessing a single file. This has the benefit of having all other drives spindown to idle if you're say streaming a movie that's contained on a single drive.

  • RAID 5 uses block level striping and distributed parity. There are plenty of articles on the net. If you want more information just google it. If you are buying good hard drives I would be more worried about the number of spindowns/spinups vs. having the drives spinning. I've had good luck not worrying about spindowns.

  • Oh I know very well what RAID 5 is. No need to google it. I think I made that clear.


    Was hoping it used a pseudo-RAID 5 such as unRAID, snapRAID, etc. as I feel that's superior to traditional RAID 5, especially in light of how far performance of HDDs and SATA controllers have come. Besides eliminating the need to have all hard drives on when accessing a single drive, it allows you to easily remove the hard drives from the "RAID" and use the drives as-is, and if a single drive fails and you cannot rebuild that failure for some reason, not all the data is compromised. The remaining drives contain whole files and not striped data.


    Data pooling with dedicated parity really is the way to go for software "RAID" solutions this day and age. Especially for a home media server, where the LAN being the bottleneck will eliminate any performance gains traditional RAID will create. It was a bit of head scratcher when Microsoft went with striped data with its new storage pooling feature in Windows 8 and given how there are virtually no benefits to using striped data for it's application, I feel the same way about OVM.

  • What you are looking for is Greyhole. On .3 OMV there is a working plugin for Greyhole. It has not been updated for .4. You might keep watching and at some point there may be a working plugin for .5 OMV.

  • OK cool thanks. Hopefully something like that does make its way for 0.5. I suppose I could always run something like SnapRAID in parallel with OMV. I also forgot to mention that a psuedo-RAID system with dedicated parity drive also gives one the benefit of being able to use several drives of varying size, and the ability to initially build the "RAID" even with existing data on the drives. With all of the benefits with the psuedo-RAID implementation of something like unRAID or SnapRAID, and really no benefits for traditional striped based RAIDs when the application is a NAS bottlenecked by the LAN bandwidth, it's a wonder why OMV wouldn't make this the default functionality :D

  • Hi All, I'm new on this forum and I'm new OMV user as well. I use to run with Openfiler. I recently discover OMV and its plugins and Whaooooo ! Amazing.
    But like bennynihon, I think that snapraid will be a very good improvement for OMV.


    Perhaps someone is able to create this plugins ;)

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