Home Server Upgrades

Last night I took this server down for an hour or two for some upgrades. First of all, it got de-dusted, and I discovered even the hermetically sealed P160 case is subject to dust and spider webs 🙁 I backed up my RAID5 data array to an external drive and then installed the drives I got through a boxing day sale. Everything slipped in nice and good. I also found that I could (theoretically), use one of the drives I took out to turn my 2x120G RAID1 array into a 3x120G RAID5. That would give 740 G of storage (I think). Only thing I need is to find the extra drive rails for that case, which I have no idea where they are.

While the system was down I threw it on a UPS as well. This is a little APC unit I aquired by default and really isn’t mine, but I’m using it for now. It’s got a USB interface that lets the computer talk to the UPS unit so the computer will shut itself down nicely if the power fails. I had to google a bit to get the info on how to set it up (how many TLAs can you find in this google search? 🙂

I found a really good apcupsd on gentoo tutorial that I followed and it worked great (once I turned on USB on the server that is). The test shutoff went well, and while I didn’t do a “live” shutdown due to loss of power, I have every confidence it will work fine.

Now I’m in the wonderful world of figuring out how the hell EVMS really works and how to use it. I think it can do what I want, which is (in theory) create a single massive partition (that appears to the system as a single device to put a filesystem on) from multiple underlying storage areas, in this case, RAID arrays. So I’d have 2 RAID5 arrays, one of 500G and one of 240 and they would combine seamlessly as a volume group into something that I could just mount as /mnt/storage. Of course, doesn’t that lose the security of RAID if one of those RAID5 arrays failed? Isn’t what that is creating (as I read it from the some of the docs). Of course I could have 2 separate data partitions, but I thought the whole point of EVMS was to scale…..

I asked about this before, with no real de-confusion on my part. Oh well, off to find more howtos and tutorials I guess.

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4 Comments on “Home Server Upgrades”

  1. EVMS is the manager, it would actually be a volume group overlaid over 2 raid5 vols. The EVMS is just the management tool. However, yes, that’s what I was thinking, and wondering how you’d avoid if one array went down. Yes though, you’re right, 2 drives would have to go down to lose that situation….

  2. If you have 2 RAID5 arrays, isn’t that a level removed? Ie one level is RAID5 while the other is EVMS mounted on the RAID5 volumes. If so, then if one of these RAID5 arrays were to fail, then yes, EVMS would die. BUT for one of the RAID5 arrays to die you would need a minium of TWO dead drives.
    I’m not familiar with EVMs, but from your description, I think that is where the confusion could be coming from.

  3. You would lose one of those drives to parity so you would really have only 500gig of space.