<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd"><html><head><meta name="qrichtext" content="1" /><style type="text/css">p, li { white-space: pre-wrap; }</style></head><body style=" font-family:'Sans Serif'; font-size:10pt; font-weight:400; font-style:normal;">On Monday 15 June 2009 21:29:58 Jim Cheetham wrote:<br>
> On Mon, Jun 15, 2009 at 2:30 PM, <james@booths.net.nz> wrote:<br>
> > Having just had a near-death experience with my non-RAID LVM system<br>
> > for Myth, I am about to convert everything to a RAID-5 setup (software<br>
> > RAID) with LVM on top.<br>
><br>
> Even though it's been said before on this thread, I'll say it again ...<br>
><br>
> Don't use RAID-5. The failure modes you get in RAID-5 coupled with the<br>
> disk health information available to the OS (i.e. basically none) mean<br>
> that you stand a reasonable chance of losing all your data<br>
> unexpectedly. RAID5 is a disk storage model based on a different<br>
> economic value for disks/controllers to how we operate today. Don't<br>
> use it :-)<br>
><br>
> You are storing archive data, so you don't need write performance,<br>
> just read performance. RAID1 is your simplest friend. Simplicity means<br>
> it's quick to recover when things go wrong. And they will :-)<br>
><br>
> You can have multiple disks in your RAID1 for redundancy, three would<br>
> be plenty. Two is probably acceptable, given the delivery times for<br>
> new disks these days. LVM on top gives the flexibility for growing &<br>
> importing volumes, but you know that.<br>
><br>
> > Before I go ahead does anyone have any<br>
> > recommendations on best choice of file system to use, given that it<br>
> > will be within LVM on RAID-5? I was going to go with XFS, but that<br>
> > cannot be shrunk, which (as I have found) can be very irritating when<br>
> > trying to reorganise your disks in an LVM.<br>
><br>
> Why shrink a filesystem? I guess if you haven't figured out how you<br>
> want to store things, perhaps ... but in general, filesystems only<br>
> grow :-)<br>
><br>
> Just stick with ext3 unless you really know the details of why you're<br>
> using something else (yes, not very sexy is it?). XFS should be good<br>
> by default for large objects, but you already don't like that ...<br>
><br>
> -jim<br>
><br>
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<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; -qt-user-state:0;"><br></p>Well, I was orriginally considering RAID-1, the only issue being that I would run out of SATA ports.<br>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; -qt-user-state:0;"><br></p>I need around 3TB of working storage, and have four 1.5TB drives. I also have a DVD drive, giving a total of five drives. I have six SATA ports.<br>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; -qt-user-state:0;"><br></p>If I go RAID-1 then I get my 3TB, but cannot add in an extra pair of disks to expand storage. With RAID-5 I can add in an extra 1.5TB drive. Yes, I could add in another drive controller, but it all starts adding to the expense etc.<br>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; -qt-user-state:0;"><br></p>To be sure, I agree with you that RAID-1 is probably best, but while the "economic model" may have changed, the storage requirements have gone up dramatically as well.<br>
<p style="-qt-paragraph-type:empty; margin-top:0px; margin-bottom:0px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px; -qt-user-state:0;"><br></p>I can see a seperate server with a bazillion TB of storage set up as RAID-10 in my future, but probably not just yet...<br>
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