#296747 - 18/04/2007 20:45
Re: Hardware RAID Advice
[Re: Robotic]
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Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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#296748 - 18/04/2007 20:55
Re: Hardware RAID Advice
[Re: Neutrino]
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Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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Last night I was playing around and downloaded FreeNAS. I have an extra PC that is really quite an overkill for this but I used it anyway just to take a look at it. FreeNAS is a cinch to setup. Took maybe 30 minutes start to finish to have a NAS on the network. I only hooked up 1 drive just for testing and it went without a hitch. It took 4 minutes and 39 seconds to transfer a 1GB file across the LAN to the NAS. Network utilization ran from 15 to 65%. Not too bad really. I can see why this can be a popular alternative. I should have my Slug tomorrow. I'll set that up and see how it compares. It will provide a much less energy hungry solution but I have no idea what the speeds are going to be like. With a 266mhz clock I have my doubts.
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#296749 - 18/04/2007 21:24
Re: Hardware RAID Advice
[Re: mlord]
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pooh-bah
Registered: 06/04/2005
Posts: 2026
Loc: Seattle transplant
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Quote:
If the onboard IDE is a real drive, then I'd install the O/S there. If the onboard IDE device is a flash thingie, then I'd likely just put the /boot partition there, and everything else onto the RAID array. In fact, the latter is what I often recommend.
Cheers
Thanks, Mark!
What if I install Linux on an old 1GB microdrive through those CF/IDE adaptors like in the CF empeg thread!
(Just kidding- I'd expect performance would suffer. Meanwhile, I've got a couple of useless microdrives hanging around.)
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10101466 (2x60GB, Eutronix/GreenLights Blue) (Stolen!)
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#296750 - 18/04/2007 21:34
Re: Hardware RAID Advice
[Re: Robotic]
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pooh-bah
Registered: 12/02/2002
Posts: 2298
Loc: Berkeley, California
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Quote:
Meanwhile, I've got a couple of useless microdrives hanging around.)
Open them up and frame them... I've never seen the inside of one, but I've always considered them an amazing technical accomplishment.
Matthew
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#296751 - 18/04/2007 22:45
Re: Hardware RAID Advice
[Re: Robotic]
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carpal tunnel
Registered: 08/06/1999
Posts: 7868
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Quote:
Use an IDE expansion PCI card (I'm thinking most often such cards are sold as 'raid controllers', but I haven't investigated this at all, so I may be going in the wrong direction) to allow more drives to be connected to the motherboard.
I'm using two different PCI IDE controllers in my server currently, one that only does normal drive access, and one that offers some sort of raid protection. The RAID card has a mini bios setup program to setup the RAID, and if you never go in there and set it up, it just runs as a normal IDE controller. Linux sees both controllers the same way, and just accesses the disks directly.
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#296752 - 18/04/2007 22:59
Re: Hardware RAID Advice
[Re: drakino]
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Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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I'm using a Promise Ultra/133 2 channel ide / pci card to access more PATA drives. This can be had cheap! One of these days all my PATA drives (7) will have died and I will move on....
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#296753 - 18/04/2007 23:04
Re: Hardware RAID Advice
[Re: Neutrino]
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addict
Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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OK, I added a second drive to the FreeNAS sytem and made a RAID1 system. One drive is connected via the secondary channel of IDE1 and the other is through a USB port. Not a conventional construct but it seems to work. Transfer time for a 1GB file has increased to 5:36. Interesting....
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#296754 - 19/04/2007 00:52
Re: Hardware RAID Advice
[Re: matthew_k]
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carpal tunnel
Registered: 29/08/2000
Posts: 14496
Loc: Canada
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Quote:
Quote:
Meanwhile, I've got a couple of useless microdrives hanging around.)
Open them up and frame them... I've never seen the inside of one, but I've always considered them an amazing technical accomplishment.
Presenting.. a GeoCaching "Travel Bug" in my honour: the actual item that was inside my camera at the 2003 Empeg Owners' Meet:
I tore the cover off, and later left it as loot in a geocache. Another local cacher retrieved it, and converted it into a "travel bug" named "Mlord's Micro Drive" (TBAF86).
Cheers
Edited by mlord (19/04/2007 00:57)
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#296755 - 19/04/2007 00:56
Re: Hardware RAID Advice
[Re: Robotic]
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carpal tunnel
Registered: 29/08/2000
Posts: 14496
Loc: Canada
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Quote:
What if I install Linux on an old 1GB microdrive through those CF/IDE adaptors like in the CF empeg thread!
(Just kidding- I'd expect performance would suffer. Meanwhile, I've got a couple of useless microdrives hanging around.)
Heh.. they'd be just fine for the /boot drive, but I didn't find them terribly reliable -- my original died after a small jolt, as did it's replacement.
Still, nifty little things. Would you sell me one, and if so, for how much? (I miss my old ones).
My email address is in my BBS profile.
Cheers!
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#296756 - 19/04/2007 04:45
Re: Hardware RAID Advice
[Re: mlord]
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pooh-bah
Registered: 06/04/2005
Posts: 2026
Loc: Seattle transplant
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Quote:
Still, nifty little things. Would you sell me one, and if so, for how much? (I miss my old ones).
You've got mail!
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10101311 (20GB- backup empeg)
10101466 (2x60GB, Eutronix/GreenLights Blue) (Stolen!)
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#296757 - 19/04/2007 06:19
Re: Hardware RAID Advice
[Re: Seth]
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Registered: 11/01/2002
Posts: 612
Loc: Reading, UK
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I forgot to comment on this  : Quote:
I'm curious what others think of this card or other similar cards. Should I just throw it in the garbage?
I wouldn't use their RAID capability - but if you have one then I'd use it as a multi-drive controller card.
Actually, you may or may not know that many cheap RAID cards are just simple multi-channel controllers - as this tongue-in-cheek FAQ says...
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Running twin 30's
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#296758 - 19/04/2007 07:21
Re: Hardware RAID Advice
[Re: LittleBlueThing]
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carpal tunnel
Registered: 24/12/2001
Posts: 5528
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Quote:
Actually, you may or may not know that many cheap RAID cards are just simple multi-channel controllers - as this tongue-in-cheek FAQ says...
The Promise PATA "RAID" cards were actually their normal PATA controllers but with a different firmware and a resistor moved to change the chip ID. If you changed the resistor then you could reflash it with the RAID firmware. Not really that useful tho...
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#296759 - 19/04/2007 08:12
Re: Hardware RAID Advice
[Re: LittleBlueThing]
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carpal tunnel
Registered: 18/01/2000
Posts: 5683
Loc: London, UK
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Quote:
many cheap RAID cards are just simple multi-channel controllers
Yeah, it's often all in the drivers, with maybe some acceleration features on the card.
It's usually better to use the card in JBOD mode (just a bunch of disks), and rely on the OS's software RAID. On Linux, anyway -- I've never tried Windows' software RAID.
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#296760 - 19/04/2007 21:16
Re: Hardware RAID Advice
[Re: Roger]
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Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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I got "the slug" today. You gotta love newegg. Great service, fast shipping. Anyway, it won hands down on speed against FreeNas on my simple test of writing a 1gb file to it. I was able to write the same file to the slug that I did to the Freenas box in just 3:23. This is a full minute faster. It's as cute as a bug too. Pretty cool for 80 bucks.
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#296761 - 19/04/2007 23:26
Re: Hardware RAID Advice
[Re: Neutrino]
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member
Registered: 12/08/2001
Posts: 175
Loc: Atlanta
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I don't suppose you have a Kill-A-Watt or something similar to measure the power drain of the slug, do you? Can you tell me what the power supply is rated to get an upper bound?
I would like to get a NAS but I want low power. I was going to look at a DNS-323, but I would prefer something that took external USB drives rather than internal drives.
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#296762 - 20/04/2007 04:22
Re: Hardware RAID Advice
[Re: Folsom]
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Registered: 23/01/2002
Posts: 506
Loc: The Great Pacific NorthWest
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It uses the same 5vdc @ 2amp powersupply as most everything else I've bought from Linksys lately so it must not draw more than 10watts. I would expect half that is more like it. It runs pretty much stone cold.
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#296764 - 25/04/2007 01:53
Re: Hardware RAID Advice
[Re: LittleBlueThing]
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new poster
Registered: 15/04/2007
Posts: 15
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Quote:
I wouldn't use their RAID capability - but if you have one then I'd use it as a multi-drive controller card.
Problem is that I cannot seem to get that card to present an individual disk as just a single volume. The interface isn't that intuitive, but I've tried just about everything and it seems that I have to create some sort of array between 2 or more disks before I can actually get to the step of creating a volume. If I don't create a volume, then the drive is essentially invisible to the system. Otherwise I DID think of doing that, I just haven't figured it out with that card yet.
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#296766 - 07/05/2007 19:31
Re: Hardware RAID Advice
[Re: wfaulk]
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new poster
Registered: 15/04/2007
Posts: 15
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Looks like I was trying the impossible. I had a RAID 5 array defined as the first drive and was trying to make a fourth drive a single drive. According to that I have to do the opposite....
Thanks for pointing that out.
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#296767 - 04/06/2007 19:06
Re: Hardware RAID Advice
[Re: Cris]
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carpal tunnel
Registered: 29/08/2000
Posts: 14496
Loc: Canada
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Quote:
I can really see the disadvantage of not having any tools to monitor the array. I think that the drive would begin to recover, but when I re-booted it started over. I couldn't see a way of checking, even from the command line in freenas, what stage the rebuild was at. The only place tht told me that was the RAID's BIOS.
cat /proc/mdstat
or even:
watch -n1 cat /proc/mdstat
Edited by mlord (04/06/2007 19:06)
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#296768 - 20/06/2007 02:39
Re: Hardware RAID Advice
[Re: mlord]
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pooh-bah
Registered: 06/04/2005
Posts: 2026
Loc: Seattle transplant
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Quote:
...nifty little things...
Quote:
2 Pack of Hitachi 4GB Microdrive for $24.99 Shipped
on woot today- missed it!
_________________________
10101311 (20GB- backup empeg)
10101466 (2x60GB, Eutronix/GreenLights Blue) (Stolen!)
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#296769 - 24/08/2007 10:48
Re: Hardware RAID Advice
[Re: mlord]
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carpal tunnel
Registered: 29/08/2000
Posts: 14496
Loc: Canada
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Quote:
I found this set of instructions that I'm using as a loose guide for this:
http://www.debian-administration.org/articles/512
Somebody PM'd me this week, asking why that article designated one "drive" as a "hot spare" in a RAID1 array.
I very much prefer such questions to be asked in the forums/threads, like now, rather than in PM -- because this way everyone gets to see the question and contribute to the answers, and it's all nice and searchable afterward.
So, back to the question: why a "hot spare" for RAID1? Well, normally that would not make much sense to most people, as the entire concept of RAID1 is a bunch of "hot spares" kept up-to-date in parallel. But in this case, the RAID1 was just a small partition of each drive, and the bulk of the space was in a RAID5 array. A "hot spare" makes good sense for RAID5, and so that's why they did it that way.
The idea is that when a RAID5 drive fails, the system suddenly has no redundancy, so it becomes imperative to configure/update a new drive immediately --> the hot spare.
And since that article was treating all drives more or less the same, they decided to "hot spare" the RAID1 partition of that same drive for consistency. So that the drive could be removed/replaced/whatever at any time without impacting either of the two RAIDs.
There's also a typo in that article, where in the section dealing with RAID5 they accidently use "RAID1" in one of the instructions:
Now you will want to choose Create MD device again.
* Multidisk device type: RAID5
* Number of active devices for the RAID5 array: 3
* Number of spare devices for the Raid1 array: 1
Cheers
Edited by mlord (24/08/2007 10:54)
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#296770 - 24/08/2007 14:26
Re: Hardware RAID Advice
[Re: mlord]
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carpal tunnel
Registered: 10/06/1999
Posts: 5916
Loc: Wivenhoe, Essex, UK
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Surely a hotspare for RAID1 has more uses that just that. If if you have three disk and use all of them in your RAID1 array then the OS has to write to all three disks all the time.
If you make the third disk a hotspare instead then you won't have to take the overhead of writing to the third disk normally, but if one of the other disk fails a rebuild to the hotspare will start without any intervention.
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#296771 - 24/08/2007 14:35
Re: Hardware RAID Advice
[Re: andy]
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addict
Registered: 11/01/2002
Posts: 612
Loc: Reading, UK
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... and you can have a hot spare shared between multiple arrays.
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#296772 - 24/08/2007 14:52
Re: Hardware RAID Advice
[Re: LittleBlueThing]
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carpal tunnel
Registered: 10/06/1999
Posts: 5916
Loc: Wivenhoe, Essex, UK
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Does that work in the same way on Linux software RAID as it does on hardware RAID, i.e. can does the hot spare have to have the right partitions it place or can it be a unpartitioned disk ?
(my RAID1 Debian box doesn't have any hotspares yet)
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#296773 - 25/08/2007 23:15
Re: Hardware RAID Advice
[Re: andy]
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new poster
Registered: 15/04/2007
Posts: 15
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I was the offender..... :0 Sorry about that.
I think the thing that I didn't understand was what the config was actually doing in an operational sense. Andy sort of touched on it here.
The article had three drives in the RAID1 array. Since RAID1 is mirroring, I've never seen 3 drives in a mirrored array. So I was wondering if one drive is actually mirrored to the other 2 in the array.
Then on top of that, the RAID1 array had a spare drive..... So three active, 1 spare. I wasn't sure what that meant it was doing.
So it sounds like this...someone correct me if I am wrong:
- All writes to the boot partition are mirrored to two other drives.
- If any one of the three drives fails, the fourth will automatically join the array so that the first partition is still mirrored to two others.
- If the first drive fails, then the system would boot off drive two which would then be mirrored to drive three and four.
As an aside, the main thing that I didn't like about the article was that it presumed with just 4 drives that you want a hot spare. Well, if I wanted half my total drive capacity, I'd just use RAID1 in the first place. I'm using RAID5 to get more storage space and have it be resilient. I have a spare sitting on my shelf and am not too lazy to plug it in if I need it :-).
Which brings me to another question. Anyone know of any drive monitoring software that can detect drive failures and send an email or an alert of some sort. For my needs, that is sufficient...I don't need a hot spare if I can get notification when there is a problem.
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#296774 - 25/08/2007 23:21
Re: Hardware RAID Advice
[Re: Seth]
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new poster
Registered: 15/04/2007
Posts: 15
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Forgot the other question I had. Any recommendations on encrypted file systems?
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#296775 - 26/08/2007 07:29
Re: Hardware RAID Advice
[Re: Seth]
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carpal tunnel
Registered: 10/06/1999
Posts: 5916
Loc: Wivenhoe, Essex, UK
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Quote:
Which brings me to another question. Anyone know of any drive monitoring software that can detect drive failures and send an email or an alert of some sort.
"aptitude install smartmontools" though you need a relatively recent setup for that to work with RAID (i.e. it doesn't work on Debian Sarge, but it does on Etch).
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#296776 - 26/08/2007 15:10
Re: Hardware RAID Advice
[Re: andy]
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addict
Registered: 11/01/2002
Posts: 612
Loc: Reading, UK
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and, of course, mdadm runs in monitoring mode and sends emails like these: Code:
This is an automatically generated mail message from mdadm
running on haze
A DegradedArray event had been detected on md device /dev/md0.
Faithfully yours, etc.
P.S. The /proc/mdstat file currently contains the following:
Personalities : [raid1] [raid6] [raid5] [raid4]
md1 : active raid5 sdd1[0] sda1[2] sdc1[1]
390716672 blocks level 5, 64k chunk, algorithm 2 [3/3] [UUU]
md0 : active raid1 sdc2[1]
3783232 blocks [2/1] [_U]
unused devices: <none>
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