[mythtv-users] LVM RAID 5 partition schemes

[dean collins]

Time to look at a Silent Star Dual Drive water cooling case possibly?

I use one of these in each of my 3 pc's (not using MythTV yet)

Cheers,
Dean



-----Original Message-----
From: mythtv-users-bounces at mythtv.org
[mailto:mythtv-users-bounces at mythtv.org] On Behalf Of David
Sent: Wednesday, April 06, 2005 5:05 PM
To: Milan Andric
Cc: Discussion about mythtv
Subject: Re: [mythtv-users] LVM RAID 5 partition schemes

Milan Andric wrote:

>>It'll be noisy and, more worryingly - very hot!
>>    
>>
>Yeah I'm obviously worried about that, figured there's only one way to
>find out ...
>
>there's probably no way around the noise ... for now until i can make a
backend
>in a basement or somewhere. right now i have an apt. i'm beginning to 
>think i'll need to stick the fileserver in a tower/desktop case.
>
>what type of case do you suggest as a minimum for raid 5, + OS drive?
>ie. 3-5 drives.  
>  
>
I use a full tower with the drives in the top half. You may get away 
with a half tower but the circulation is usually worse.
I cut a circular hole in the top and vent via a 12cm fan.
If you go for a bigger case then you can put sound absorbing material 
(which should alleviate the hard disk whine) and bigger (hence slower 
and quieter) fans in it. If you can move air through the case then heat 
should be less of an issue.
Given the 250 also pumps out heat, as will any graphics card, this may 
be best although it obviously won't sit on a shelf looking cute.
You sound like you're spending money carefully so maybe do what I did 
and get a cheap beige tower and paint it (with car-paint). It looked 
surprisingly good. I then put a branded 550W PSU in.

>if i change my route from microATX behemoth I'd likely make my current 
>desktop computer a file-server/myth backend and purchase HW
>for a frontend. 
>
>there's a problem with that.
>1) no wired network to bedroom, just wireless 802.11B 5-8Mb/s?
>  
>
mmm - if that speed is reliable then it's fine - but if you end up with 
the connection dropping with an nfs mount trying to write then my 
experience is that ivtv goes AWOL. I'd avoid a wireless connection 
unless you feel it's as stable as wire.
To emphasise - the speed is generally not an issue.

>>nope - can't do that :)
>>You can start with a 3-drive raid5 with 1 missing (ie 2x300Gb) and add
a
>>3rd later.
>>
>>But you'll have no redundancy until you buy the 3rd drive.
>>You also can't 'add drives as time goes by' to a raid 5.
>>    
>>
>unless i use the 'missing' trick?
>  
>
nope.
The only way to add drives is an unsupported program called raidreconf 
or using the (supported) EVMS solution.
Sean's idea of lots of mini-raid5'ed partitions is very interesting 
though. I haven't thought it through. I think you could do it just using

the lvm 'move blocks' approach (ie without needing to repeatedly 
shrink/grow the filesystem - just one growfs at the end).
I'd rate it as lvm/md experts only (which isn't that hard TBH)

>>yes.
>>I have 6x250 Gb sata drives making a raid5 array
>>The 6th 'spare' drive is a 250Gb partition on a 300Gb PATA drive - and
I
>>have had it as part of the array with no issues at all.
>>    
>>
>
>dang. what case do you use? and powersupply/fan?
>  
>
as above :)
And it's just a fileserver.

David

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