Multi Disk array

Flarkis · Posted: Mon Jul 27, 2009 5:43 am Post subject: Multi Disk array

My problem is prety simple and probably a one word answer. I am setting up a server computer in my house to host music, photos, and videos. My means are rather limited for the time being and i only have an 80gb drive, a 40gb drive, and a 30gb drive. What i am trying to do is set them up so they will appear as a 150gb drive.

From the little bit of reading around ive done it seems as though using raid0 will only use the size of the smallest disk. So 20gb*3. But im not sure about the validity of what i read. And i dont think LVM is what im looing for.

Any insight?
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Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

RAID0 is not a perfect solution: if any of your HDDs will fail (BTW: it looks like your disks are old, so this event has a very high probability), - you'll lose all your data! I suggest to make a small (mine is 256Mb!) RAID1 (2 x mirror + 1 spare) root partition (ext3) and other space dedicatate to LVM. It lets you to utilize all your disks capacity and to simplify future HDD replacing and upgrading procedures. Do not forget to start SmartMon as well!

Kollin · Posted: Mon Jul 27, 2009 10:16 am Post subject:

Common desktop hard drives behaved very badly on my raid 10, i was forced to replace them all with raid edition hdds (thanx god i`ve lost only my home partition). Did you consider NAS (with gigabit ports, there are even NASs with raid) for storage of your precious data? :idea:

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Flarkis · Posted: Mon Jul 27, 2009 6:07 pm Post subject:

This rig is more for convenience than anything else. I am not worried at the moment about data security/safety. Everything being stored on the computer will have a backup somewhere any ways. For example my mother would like a way to get her photos without having to grab her backup CDs all the time.

Just a little bit more information about the computer being turned into the server. Its an old dell with 1.8ghz centrino 2, 512gb ram, and room for 4 HDDs. Also we are only going to be using it for about a year, and hardly a heavy work load on it.

Reading about the NAS that seems like more or less what im setting up. But the computer will still have a keyboard mouse and screen.

@sysa
From what i understand your suggestion is to make my root partition on raid1 and use the rest of the disk space as LVM so i can utilize the disk to the fullest. This seems like an ideal situation. My only problem is i dont quite undertand what you mean about the root partition. RAID1 is mirror, so every disk would have a mirror of the root. I dont understand what you mean about "...+ 1 spare". Also what would be the advantages to mirroring the root partition. Other than theoretically faster load time of libraries, programs, etc.

Thanks for the help so far guys
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cach0rr0 · Posted: Mon Jul 27, 2009 7:28 pm Post subject:

respectfully, I think LVM is *precisely* what you're looking for.
It would accomplish this task perfectly.

RAID in this case would be more of a pain to set up than it's worth, for nominal benefit. Don't fuss with RAID, just set up your usual partitions, then one large LVM volume spanning the free space on each disk

Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

cach0rr0 · Posted: Mon Jul 27, 2009 7:54 pm Post subject:

Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

cach0rr0 · Posted: Mon Jul 27, 2009 8:32 pm Post subject:

Flarkis · Posted: Mon Jul 27, 2009 8:39 pm Post subject:

Ok well thanks for all the help everyone. I have decided what setup i am going to use. Being that this is also a learning experiment for me i figure i will try and set up both a RAID0 and LVM.

@ Sysa
Thanks for all the great advice.

BTW for the rest of you. This being a server that will only be turned on when i need it, rebooting is hardly a problem. I also mentioned earlier that there would not be a heavy load on this. Nor will there ever be.

Never the less thanks to all
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hielvc · Posted: Tue Jul 28, 2009 12:52 am Post subject:

Flarkis you cant use raid0 for your boot partition. Grub doesn't understand raid0. So on your 80gig mske 30 to 50meg partition for /boot. ALso I assume that these are IDE ? If so do you also have a CDRW or DVD ? This can really slow down your down your raid.
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Flarkis · Posted: Tue Jul 28, 2009 12:57 am Post subject:

I always made a unique /boot. But thanks anyways. As for the CDRW i dont understand exactly what you mean about how this could slow things down.
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hielvc · Posted: Tue Jul 28, 2009 1:12 am Post subject:

IDE runs at the fastest speed of the slowest device. CD's and DVD drives are slow slow slow, usually ata33. Your HDs are probably ATA 66, 100 or 133. You can still do raid0 but it wont be as fast as if there wasn't CD drive on the same IDE as one of the HDDs. I would put the slowest drive on the same IDE as the CD drive.
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Flarkis · Posted: Tue Jul 28, 2009 3:20 am Post subject:

ahhh. Ok thank you. Guess that makes sense. Well the current CD drive is broken and i was just scavenging one from a computer laying around the house for the soul purpose of booting the live cd. Ill keep your thought in consideration.
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Sysa · Apprentice Joined: 16 Mar 2005 Posts: 161 Location: Europe

Flarkis · Posted: Tue Jul 28, 2009 4:49 pm Post subject:

haha thanks...well i was able to find a 4th drive laying around the house to it now looks like my system will have around 310gb. And again doesn't really matter if these things are slow. Im now putting the computer together from 3 old ones laying around and anything that friends i have dont need.
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