[mythtv] Problems with using LVM for large storage
Ed Wildgoose
lists at wildgooses.com
Mon May 16 13:29:57 UTC 2005
Neale Swinnerton wrote:
>Why is this a surprise? You have one logical drive composed of multiple
>physical drives and a bit of it fails. This would be the same if you had
>one physical drive.
>
>Why not use RAID-{1|5} drives as the PV's in your LVM volume group ?
>
>
Storage space drops... You now need up to twice as many disks basically
Consider having three disks mounted as /store1, /store2 and /store3.
Now you can take down any one of them and the other two are still
accessible.
With Raid0 though you lose the whole array. There is sometimes another
mode called JBOD which can sometimes work where a failed disk just
looses you some (parts) of the files, but I have never tried this...
I can see some definite merits in the idea of having multiple store
locations, even if the record location is fixed and you have to shuffle
them around later.
I just bought a new 400Gb drive to replace the 300Gb on in my current
machine. There is 1Tb on another fileserver in RAID5. One thing which
becomes apparent with this amount of storage is that it's quite hard to
shuffle things around later and upgrade the odd disk here and there...
It's very easy to sit there and say make it Raid 1/5, but the cost,
heat, power noise and size requirements are considerable - not to
mention the hassle when you need to upgrade
Ed W
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