Re: Raid 5: Lossless music archive server recommendations

Re: Raid 5: Lossless music archive server recommendations

[TJ Harrell]

I'm aiming at a very similar setup as what you're talking about. Whether or
not you put your root on the raid is up to you. Personally, I don't, and I
have my raid mounted as /home. Anyways, your mobo should support two drives,
and each additional controller should support two drives. Thus, with one
addon controller, you can have 4 drives. With 200GB drives, that's 600GB of
space doing RAID 5. In my experience, adding more drives to an array is
extremely easy, but it is dangerous. It is possible to lose data even if you
do follow the steps verbatim, although I've done it 3-4 times myself with no
trouble. First, you must use raidreconf to grow the array onto the new disk,
then you must use resize2fs to expand the filesystem to fill the array.
Backing up during this process is highly recommended!

I personally don't use a hot spare, and I haven't had any trouble with drive
failure since I got rid of all my IBM drives. I did have a run in with a WD
drive that needed a firmware update else it dropped out of the array
periodically, though. A hot spare is something to take into consideration.
Also, you might look into some sort of monitoring script. If you don't
monitor the array, you could lose one disk and go months without ever
knowing. Something that would email you would be ideal.

Re: Raid 5: Lossless music archive server recommendations

[M K]

you can setup mdadm in the monitor mode and configure
it to send email alerts.

--- TJ Harrell <systemloc@earthlink.net> wrote:
> I'm aiming at a very similar setup as what you're
> talking about. Whether or
> not you put your root on the raid is up to you.
> Personally, I don't, and I
> have my raid mounted as /home. Anyways, your mobo
> should support two drives,
> and each additional controller should support two
> drives. Thus, with one
> addon controller, you can have 4 drives. With 200GB
> drives, that's 600GB of
> space doing RAID 5. In my experience, adding more
> drives to an array is
> extremely easy, but it is dangerous. It is possible
> to lose data even if you
> do follow the steps verbatim, although I've done it
> 3-4 times myself with no
> trouble. First, you must use raidreconf to grow the
> array onto the new disk,
> then you must use resize2fs to expand the filesystem
> to fill the array.
> Backing up during this process is highly
> recommended!
> 
> I personally don't use a hot spare, and I haven't
> had any trouble with drive
> failure since I got rid of all my IBM drives. I did
> have a run in with a WD
> drive that needed a firmware update else it dropped
> out of the array
> periodically, though. A hot spare is something to
> take into consideration.
> Also, you might look into some sort of monitoring
> script. If you don't
> monitor the array, you could lose one disk and go
> months without ever
> knowing. Something that would email you would be
> ideal.
> 
> 
> -
> To unsubscribe from this list: send the line
> "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at 
http://vger.kernel.org/majordomo-info.html



	
		
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Re: Raid 5: Lossless music archive server recommendations

[Lucas Albers]

I have a system that uses drives on all channels, eg master/slave.
and I have encountered any slowdown, by using primary and secondary disks
in the same channel.
Yes it is slower, but for me performance is good enough.

It serves upwards of 100gigs of data over the network per day.
I use mdadm on all my raid systems, as it was easier to setup and has
automatic email notification.
I wrote a document on using mdadm. http://rootraiddoc.alioth.debian.org

I'm trying to put hot spares in my systems because I'm getting perhaps 1
disk failed every 2 weeks to a month.
It does seem a waste of space, but hard drives are cheap.

-- 
Luke Computer Science System Administrator
Security Administrator,College of Engineering
Montana State University-Bozeman,Montana

Re: Raid 5: Lossless music archive server recommendations

[TJ Harrell]

> I have a system that uses drives on all channels, eg master/slave.
> and I have encountered any slowdown, by using primary and secondary disks
> in the same channel.
> Yes it is slower, but for me performance is good enough.

With two drives per channel, doesn't a disk failure pull down the other
drive, causing the entire array to fail, and require a reboot to bring the
degraded array back online?

Re: Raid 5: Lossless music archive server recommendations

[dean gaudet]

On Tue, 1 Jun 2004, TJ Harrell wrote:

>
> > I have a system that uses drives on all channels, eg master/slave.
> > and I have encountered any slowdown, by using primary and secondary disks
> > in the same channel.
> > Yes it is slower, but for me performance is good enough.
>
> With two drives per channel, doesn't a disk failure pull down the other
> drive, causing the entire array to fail, and require a reboot to bring the
> degraded array back online?

yes that is an additional failure mode possible when you use two ata
drives on a channel.  this isn't really a recommended configuration.

you might have to dork with raid superblocks to recover from such a
failure.  in fact chances are you *will* have to dork with raid
superblocks to recover.

-dean

Re: raid on extended partitions

[Neil Brown]

On Monday May 31, maheshext3@yahoo.com wrote:
> Hello folks, I am using kernel version 2.4.18-ac3,
> mdadm - v1.2.0 - 13 Mar 2003 and wanted to take a shot
> at creating a RAID on an extended partition using
> mdadm.
> the commands used were (all drives were swapped off an
> unmounted before running these, and I am running on a
> motherboard with 4 IDE channels; the drives used were
> /dev/hde and /dev/hdg):
> Fdisk RESULT for hde (same on hdg as well):
>    Device Boot    Start       End    Blocks   Id 
> System
> /dev/hde1             1      9052  72710158+  83 
> Linux
> /dev/hde2          9053     36473 220259182+   5 
> Extended
> /dev/hde5          9053     12877  30724281   fd 
> Linux raid autodetect
> 
> Calling ioctl() to re-read partition table.
>  hde: hde1 hde2 < hde5 >
>  hde: hde1 hde2 < hde5 >
> Syncing disks.
> 
> After that, When I tried to run:
> mdadm --create --force /dev/md3 --raid-devices=2
> --level=1 /dev/hde5 /dev/hdg5
> 
> I get:
> mdadm: Cannot open /dev/hde5: No such file or
> directory
> mdadm: Cannot open /dev/hdg5: No such file or
> directory
> mdadm: create aborted

What does
   ls -l /dev/hd[eg]5
show? How about
   cat /proc/partitions
   dd if=/dev/hde5 of=/dev/null bs=1024k

NeilBrown

> 
> I am using mdadm - v1.2.0 - 13 Mar 2003

Not the most recent .....  but it should still work.

Re: raid on extended partitions

[M K]

--- Neil Brown <neilb@cse.unsw.edu.au> wrote:
> 
> What does
>    ls -l /dev/hd[eg]5
> show? How about
>    cat /proc/partitions
>    dd if=/dev/hde5 of=/dev/null bs=1024k

Thanks a lot, Neil, turns out those nodes were not
present. After I mknod'd them, all's fine in
RAIDland... 
  Quick question: does using extended partitions for
RAID affect performance?
Cheers,
Mahesh



	
		
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Re: raid on extended partitions

[Neil Brown]

On Tuesday June 1, maheshext3@yahoo.com wrote:
> 
> --- Neil Brown <neilb@cse.unsw.edu.au> wrote:
> > 
> > What does
> >    ls -l /dev/hd[eg]5
> > show? How about
> >    cat /proc/partitions
> >    dd if=/dev/hde5 of=/dev/null bs=1024k
> 
> Thanks a lot, Neil, turns out those nodes were not
> present. After I mknod'd them, all's fine in
> RAIDland... 
>   Quick question: does using extended partitions for
> RAID affect performance?

The fact that the partitions are "extended" is invisible to most of
the kernel, and it could not have any affect of performance.

NeilBrown

Raid 5: Lossless music archive server recommendations

[James Bamford]

Hi folks...

Its been a while since I've asked anything on here.. after some effort you  
guys got me rolling with linux for a backup server on an old machine and  
an old promise ide controller running a simple 2 drive software raid  
mirror... Everything has been fine with it so far although its not in use  
much at the moment as the machine to be backed up has since been  
"upgraded" to be water cooled.. but i've yet to fit the controls to turn  
the pump on automatically so it can't boot up without me being around and  
so can't run the auto backup task..

ANyways.. For a long time i've been waiting for bigger harddisks to make a  
backup of my entire music catalogue a possibility, in lossless formats  
about 400meg an album.. I've just realised that this only really needs  
around 400-500gig and so is within reach of not too many hdds right here  
right now..

Its going to take some time to make these music rips and when i do i think  
i'll want them to have some kind of backup which has got me thinking raid  
again... I guess this time I would want raid5 as I need more space than is  
really feasible off only a few drives..

I'm a little wet behind the ears with all things raid but i was thinking  
that 3x200gig drives would do for the data.. needing a 4th drive for the  
raid5 parity disk or however it works..

Beyond that i do continue to buy music so some form of expandability would  
be nice.. 8 channels would allow me to scale although am i right in  
thinking that i would have to stick to the same sized drives for any extra  
drives i consider!?

I then guess i need to have seperate channels for each hdd, which starts  
taking me towards 3ware type cards with hardware to the task.. does this  
then move me away from using software raid in linux if i have to get these  
cards?

I ideally would like SATA to try it but i can't find any 200gig Seagate  
SATA drives in the UK at the moment, only Ultra ATA ..

Anyways if you experts could tell me if i've got the right idea for  
requirements that'd be great..

Thanks for your time

Cheers

Jim

-- 
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/

Re: Raid 5: Lossless music archive server recommendations

[M K]

I may be wrong, but do bear in mind that its not easy
to "expand" a RAID once you have created it. More or
less, when you need more space in the future, you may
just find it easier to create another big raid.
 also, IDE drives are not very reliable per-se. so you
may want to add another "hot-spare" to your system,
just in case more than one hard drive says bye-bye.
.. just my $0.02 of thought..

--- James Bamford <jim@jimtreats.com> wrote:
> Hi folks...
> 
> Its been a while since I've asked anything on here..
> after some effort you  
> guys got me rolling with linux for a backup server
> on an old machine and  
> an old promise ide controller running a simple 2
> drive software raid  
> mirror... Everything has been fine with it so far
> although its not in use  
> much at the moment as the machine to be backed up
> has since been  
> "upgraded" to be water cooled.. but i've yet to fit
> the controls to turn  
> the pump on automatically so it can't boot up
> without me being around and  
> so can't run the auto backup task..
> 
> ANyways.. For a long time i've been waiting for
> bigger harddisks to make a  
> backup of my entire music catalogue a possibility,
> in lossless formats  
> about 400meg an album.. I've just realised that this
> only really needs  
> around 400-500gig and so is within reach of not too
> many hdds right here  
> right now..
> 
> Its going to take some time to make these music rips
> and when i do i think  
> i'll want them to have some kind of backup which has
> got me thinking raid  
> again... I guess this time I would want raid5 as I
> need more space than is  
> really feasible off only a few drives..
> 
> I'm a little wet behind the ears with all things
> raid but i was thinking  
> that 3x200gig drives would do for the data.. needing
> a 4th drive for the  
> raid5 parity disk or however it works..
> 
> Beyond that i do continue to buy music so some form
> of expandability would  
> be nice.. 8 channels would allow me to scale
> although am i right in  
> thinking that i would have to stick to the same
> sized drives for any extra  
> drives i consider!?
> 
> I then guess i need to have seperate channels for
> each hdd, which starts  
> taking me towards 3ware type cards with hardware to
> the task.. does this  
> then move me away from using software raid in linux
> if i have to get these  
> cards?
> 
> I ideally would like SATA to try it but i can't find
> any 200gig Seagate  
> SATA drives in the UK at the moment, only Ultra ATA
> ..
> 
> Anyways if you experts could tell me if i've got the
> right idea for  
> requirements that'd be great..
> 
> Thanks for your time
> 
> Cheers
> 
> Jim
> 
> -- 
> Using M2, Opera's revolutionary e-mail client:
> http://www.opera.com/m2/
> -
> To unsubscribe from this list: send the line
> "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at 
http://vger.kernel.org/majordomo-info.html



	
		
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RE: Raid 5: Lossless music archive server recommendations

[Guy]

If you buy and extra disk to be a spare, consider RAID6.

RAID6 will allow 2 simultaneous disk failures.

RAID5 with 1 spare will support 2 disk failures, but only 1 at a time.  1
must fail, then the array rebuilds to the spare, then another can fail.
During a re-build, if a single block is bad, the re-build fails and the
drive with the read error goes off-line and the array goes off-line.  Not
pretty!  This has happened to me!!  When it happens, it is like having 2
simultaneous disk failures, RAID6 would have survived!

Guy

-----Original Message-----
From: linux-raid-owner@vger.kernel.org
[mailto:linux-raid-owner@vger.kernel.org] On Behalf Of M K
Sent: Tuesday, June 01, 2004 8:06 PM
To: James Bamford; linux-raid@vger.kernel.org
Subject: Re: Raid 5: Lossless music archive server recommendations

I may be wrong, but do bear in mind that its not easy
to "expand" a RAID once you have created it. More or
less, when you need more space in the future, you may
just find it easier to create another big raid.
 also, IDE drives are not very reliable per-se. so you
may want to add another "hot-spare" to your system,
just in case more than one hard drive says bye-bye.
.. just my $0.02 of thought..

--- James Bamford <jim@jimtreats.com> wrote:
> Hi folks...
> 
> Its been a while since I've asked anything on here..
> after some effort you  
> guys got me rolling with linux for a backup server
> on an old machine and  
> an old promise ide controller running a simple 2
> drive software raid  
> mirror... Everything has been fine with it so far
> although its not in use  
> much at the moment as the machine to be backed up
> has since been  
> "upgraded" to be water cooled.. but i've yet to fit
> the controls to turn  
> the pump on automatically so it can't boot up
> without me being around and  
> so can't run the auto backup task..
> 
> ANyways.. For a long time i've been waiting for
> bigger harddisks to make a  
> backup of my entire music catalogue a possibility,
> in lossless formats  
> about 400meg an album.. I've just realised that this
> only really needs  
> around 400-500gig and so is within reach of not too
> many hdds right here  
> right now..
> 
> Its going to take some time to make these music rips
> and when i do i think  
> i'll want them to have some kind of backup which has
> got me thinking raid  
> again... I guess this time I would want raid5 as I
> need more space than is  
> really feasible off only a few drives..
> 
> I'm a little wet behind the ears with all things
> raid but i was thinking  
> that 3x200gig drives would do for the data.. needing
> a 4th drive for the  
> raid5 parity disk or however it works..
> 
> Beyond that i do continue to buy music so some form
> of expandability would  
> be nice.. 8 channels would allow me to scale
> although am i right in  
> thinking that i would have to stick to the same
> sized drives for any extra  
> drives i consider!?
> 
> I then guess i need to have seperate channels for
> each hdd, which starts  
> taking me towards 3ware type cards with hardware to
> the task.. does this  
> then move me away from using software raid in linux
> if i have to get these  
> cards?
> 
> I ideally would like SATA to try it but i can't find
> any 200gig Seagate  
> SATA drives in the UK at the moment, only Ultra ATA
> ..
> 
> Anyways if you experts could tell me if i've got the
> right idea for  
> requirements that'd be great..
> 
> Thanks for your time
> 
> Cheers
> 
> Jim
> 
> -- 
> Using M2, Opera's revolutionary e-mail client:
> http://www.opera.com/m2/
> -
> To unsubscribe from this list: send the line
> "unsubscribe linux-raid" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at 
http://vger.kernel.org/majordomo-info.html



	
		
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