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Cross Platform, Low Powered Home Servers w/ RAID?

Posted by Cliff on from the energy-efficient-redundancy dept.

Milo_Mindbender asks: "At home I've collected too much data to easily backup, so I've been thinking about RAID5 for a little extra data security. I multiboot my computers for both Linux and Windows so I really need a RAID solution that will make the data at least readable by both OS's. I don't think this can be done on a single machine (can it?) so I'm looking to put together a Linux home server with RAID5 serving both SAMBA and NFS. Aside from the usual questions (software/hardware RAID, types of disk to use...etc) because I live by myself in an apartment I have a few tricky requirements I hope the Slashdot crowd can help me with." How would you set up a RAID5 server to perform Samba/NFS sharing duties without it wasting a lot of wattage, while it idles? "I hate to waste electricity, so how can a Linux RAID5 server be setup to automatically spin down to the lowest possible standby power use, then spin back up when a computer accesses it? I don't have a basement, garage or other remote place to put the thing, so it needs to be quiet or at least not die a thermal death if I lock it in a closet. What's the sweet spot for choosing CPU type/speed, hardware/software RAID controller, motherboard and memory to make a home server? Since this is only going to be serving a few machines (and maybe doing router/gateway duty), I'm sure there's a point where adding more CPU horsepower doesn't improve performance much. Any suggestions on motherboards, cases or even complete systems that work particularly well for this kind of small headless home server?"

9 of 94 comments (clear)

  1. Don't worry about CPU by MerlynEmrys67 · · Score: 3, Informative
    Pick an old slow CPU, it really doesn't matter at 100Mbs speeds, if you were going multi gig - well then maybe. However don't skimp on RAM - put as many 1 GB sticks in it as you have memory slots (2 GB sticks are too expensive right now, but maybe)

    Go with slower hard drives, ie 7200 RPM drives, maybe slower - and you won't have the heat problems. However you might want to look into RAID 15, so if you can get a system that will hold 6, even better.

    Now remember, to drop back CPU power, and raw disk speed for the thermal/power savings

    --
    I have mod points and I am not afraid to use them
  2. Some Ideas by Bios_Hakr · · Score: 3, Interesting

    Grab one of the Via MoBos. They'll have at least one PCI slot, onboard video and NIC, and maybe even sound if you look around.

    Then grab a PCI SATA card. It won't need RAID capability, just a ton of SATA ports.

    Attach a smallish hard drive to the master onboard PATA port and set a CDROM on the slave on the same channel. Install your SATA card and attach some big-assed SATA drives.

    Install Debian to the PATA drive and then remove the CDROM. Disable, in BIOS, everything you won't be using.

    Once you are in Debian and everything works, use 'mkraid' to initalize the SATA drives in a RAID5 config. Mount that under /mnt/storage and then use samba to share that across your network.

    Some might say that RAID5 will be too slow. But, across a network, chances are the wire will be saturated before the hard drives hit the sustained transfer rate. If you are concerned about performance, throw a Gig-E NIC in there and use RAID0+1 or RAID3.

    I'm not sure how well Linux can deal with suspending the hard drives in a RAID controller during inactivity. If the kernel can handle it, use something like 'hdparm' to sleep the drives when they aren't in use.

    Good luck, man...

    --
    I'd rather you do it wrong, than for me to have to do it at all.
  3. Search.. by Daxster · · Score: 5, Informative

    Have you even searched Slashdot, let alone google?!
    http://ask.slashdot.org/article.pl?sid=05/09/25/02 59222&tid=198&tid=4
    http://ask.slashdot.org/article.pl?sid=05/10/07/23 1223&tid=198&tid=230&tid=98&tid=4
    http://ask.slashdot.org/article.pl?sid=05/11/09/02 0242&tid=232&tid=198&tid=126&tid=4
    http://ask.slashdot.org/article.pl?sid=05/04/27/15 20246&tid=222&tid=198&tid=230&tid=4

    *cough*

    --
    Death by snoo-snoo!
    1. Re:Search.. by egarland · · Score: 3, Insightful

      The poster asks different questions than the articles linked raise and they are valid questions.

      The objectives of large scale redundant and able to be put in a closet are needs unmet by todays storage designs and are likely to be as common tomorrow as wireless ethernet is today.

      So.. basically.. snoo snoo off. :)

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      set softtabstop=4 shiftwidth=4 expandtab nocp worlddomination
  4. I'm using something like that... by TheWanderingHermit · · Score: 5, Informative

    First, I have to say I'm truly awed that you have that much data. You must really love collecting pr0n -- er, have a lot of sound and video files.

    I recently had to set up two new servers. One is for business, and one is for personal data. For both, I used RAID 5. They run NFS and Samba, with different directories shared as needed to other systems. RAID 5 is EXTREMELY simple to set up (it's a one line command, once you install mdadm, which, on Debian, installed like a dream), and I'd just suggest Googling for mdadm and tutorial. You'll get several tutorials. There's really no need to pay for hardware RAID cards on Linux (unless you're using an old, slow system). Besides, until you get into the range of something like $300, the RAID cards all do the work through drivers anyway, so you might as well just get a cheap ($10-$20) PCI IDE Controller card to add to your existing IDE channels. Just make sure it works on Linux and is NOT Adaptec (they fsck with the drive order).

    On both my systems, all the drives are the same size and model number. I figure you can't always tell if a 160GB drive is 160GB or 140GB, and I didn't want to mess with that. RAID 5 takes 3 drives, but with mdadm, you can add a spare for failover (and the monitoring daemon will e-mail an account on that system in case of failure, so you have a warning to replace the bad drive). My only concern about using the same model for all drives is that there may be a flaw in that model. I found drives that were given a large number of good reviews at NewEgg.

    You can also add more spares and more devices with mdadm, or replace faulty devices (not hot swappable, unless you have special hardware, and I don't even know if Linux supports that).

    One last note on mdadm: when you first set up a RAID 5 array with it, you'll get an immediate warning of something like a degraded event. This is normal. I think (can't remember details) mdadm and the kernel (mdadm is by the person who wrote the RAID code for the Linux kernel) don't do an exact version of RAID 5 and, instead, use something that lets it rebuild on a new drive faster than it would otherwise.

    1. Re:I'm using something like that... by swillden · · Score: 4, Informative

      You can also add more spares and more devices with mdadm, or replace faulty devices (not hot swappable, unless you have special hardware, and I don't even know if Linux supports that).

      Here's another tip: If you're using Linux software RAID, carve your drives into multiple partitions, build RAID arrays over those, then use LVM to weld them into a larger pool of storage. It may seem silly to break the drives up into paritions, just to put them back together again, but it buys you a great deal of flexibility down the road.

      Suppose, for example, that you had three 500GB drives in a RAID-5 configuration, no hot spare. That gives you 1TB of usable storage. Now suppose you're just about out of space, and you want to add another drive. How do you do it? In order to construct a new, four-disk array, you have to destroy the current array. That means you need to back up your data so that you can restore it to the new array. If there were a cheap and convenient backup solution for storing nearly a terabyte, this topic wouldn't even come up.

      If, instead, you had cut each 500GB drive into ten 50GB partitions, created ten RAID-5 arrays (each of three 50GB partitions) and then used LVM to place them all into a single volume group, when it comes time to upgrade, you will have another option. As long as you have free space at least equal in size to on of the individual RAID arrays, you can use 'pvmove' to instruct LVM to migrate all of the data off of one array, then take that array down, rebuild it with a fourth partition from the new disk, then add it back into the volume group. Do that for each array in turn and at the end of the process you'll have 1.5TB, and not only will all of your data be safely intact, your storage will have been fully available for reading and writing the whole time!

      Note that this process isn't particularly fast. I did it when I added a fifth 200GB disk to my file server, and it took nearly a week to complete. A backup and restore would have been faster (assuing I had something to back up to!). But it only took about 30 minutes of my time to write the script that performed the process and then I just let it run, checking on it occasionally. And my kids could watch movies the whole time.

      For anyone who's interested in trying it, the basic steps to reconstruct an array are as follows. This example will assume we're rebuilding /dev/md3, which is composed of /dev/hda3, /dev/hdc3 and /dev/hde3 and will be augmented with /dev/hdg3

      • pvmove /dev/md3 # Move all data off of /dev/md3
      • vgreduce vg /dev/md3 # Remove /dev/md3 from the volume group
      • pvremove /dev/md3 # Remove the LVM signature from /dev/md3
      • mdadm --stop /dev/md3 # Stop the array
      • mdadm --zero-superblock /dev/md3 # Remove the md signature from the disk
      • mdadm --create /dev/md3 --level=5 --raid-devices=4 /dev/hda3 /dev/hdc3 /dev/hde3 /dev/hdg3 # Create the new array
      • pvcreate /dev/md3 # Prepare /dev/md3 for LVM use
      • vgextend vg /dev/md3 # Add /dev/md3 into the array

      In order to make this easy, you want to make sure that you have at least one array's worth of space not only unused, but unassigned to any logical volumes. I find it's a good idea to keep about about 1.5 times that much unallocated. Then, when I run out of room in some volume, I just add the 0.5 to the logical volume, and then set about getting more storage to add in.

      --
      Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
  5. Low wattage storage array by DanteLysin · · Score: 3, Interesting

    http://www.mini-itx.com/projects/tera-itx/

  6. VIA C3 by metamatic · · Score: 3, Interesting

    VIA C3 processor. Socket 370, up to 1GHz. Runs on 11W of electricity. If you get a VIA motherboard, you'll probably find that everything has open source Linux drivers. (I know the EPIA M-series do.)

    Now, anyone know of a socket 370 motherboard that'll take 4 or more SATA drives?

    --
    GCHQ Quantum Insert installed. If only our tongues were made of glass, how much more careful we would be when we speak
  7. hmm by GigsVT · · Score: 5, Informative

    I'm surprised no one has mentioned that RAID5 is no replacement for backups.

    I guess if it's just porn you got for free or whatever it doesn't matter, but if the data is important you still need some sort of backups.

    RAID protects against:
    Disk Failure

    Backups protect against:
    Disk Failure
    Accidental Deletion
    Malicious users
    Malicious programs
    Filesystem corruption
    Errant program causing file corruption

    RAID won't protect you from any of those other things one bit.

    --
    I've had enough abrasive sigs. Kittens are cute and fuzzy.