[Novalug] SATA HD with LVM on RAID/ udev needed?

[Joseph Brinkley]

Good luck!!!!!!!!!

On Tue, Jul 1, 2008 at 8:12 AM, Brandon Saxe <brandon20va at yahoo.com> wrote:

> Thanks for the response! Very helpful advice. I have some follow-up
> questions in-line. Please keep in mind this will be my first Linux Soft-RAID
> experience.
>
> Thanks again,
>  Brandon
>
>
> --- On Sun, 6/29/08, RJ Bergeron <rbergero at gmail.com> wrote:
>
> > From: RJ Bergeron <rbergero at gmail.com>
> > Subject: Re: [Novalug] SATA HD with LVM on RAID/ udev needed?
> > To: brandon20va at yahoo.com
> > Cc: "novalug mailing list" <novalug at calypso.tux.org>
> > Date: Sunday, June 29, 2008, 7:46 PM
> > On Sun, Jun 29, 2008 at 19:26, Brandon Saxe
> > <brandon20va at yahoo.com> wrote:
> > > ?- My SATA controller is a Silicon Image and hot swap
> > is supported. Is there any special thing I need to do to
> > let the kernel know when I am about to remove/insert a
> > drive (of course after unmounting any filesystem first). Is
> > it okay to just 'umount' and unplug? Does
> > 'eject' matter here or maybe there's some SCSI
> > commands I should issue? I am not sure.
> > I've not played with the eject code, I heard it is
> > working these days
> > for SATA, but don't have anything I'm willing to
> > try it with.
> > According to http://linux-ata.org/software-status.html
> > (Search for
> > 'hotplug supprt'), you just yank it... I'm not
> > sure how the SATA
> > backplane deals with this, if at all.
> >
> > > ?- Device Names. Depending on the order the drives are
> > inserted/removed, the device name changes from anything
> > between /dev/sdd to /dev/sdf. I have also seen /dev/sdg on
> > testing. For reference, I have two other SATA drives
> > attached to mobo at /dev/sda and /dev/sdb. /dev/sdc is a
> > USB drive. Do I need to configure udev rules for each drive
> > in order for my system to function correctly? OR will RAID
> > and LVM figure all that out for me?
> > Linux's MD software writes a signature to each disk and
> > uses that to
> > figure out how to assemble the RAID. This lets you do very
> > silly
> > things like swap out PATA controllers for a stack of
> > USB->PATA
> > boxes...
>
> Are you suggesting to always use RAID or LVM even if for just one disk? I
> guess one example may be a USB external hard drive. By having LVM manage the
> disk, then LVM daemon will know exactly where to mount it every time without
> caring for the /dev node name?
>
> >
> > > ?- Should I bother dealing with udev on this one? Even
> > if RAID and LVM don't care about device names, I still
> > feel it may be helpful to know exactly which drive is at
> > which device node. Can anybody recommend why I *should* or
> > *shouldn't* do udev?
> > I would stay away from configuring udev to map drives
> > statically, it's
> > just not necessary and may confuse the MD assembly
> > processes ('seeing'
> > things twice). I actually recently replaced a failed drive
> > (through
> > coldplug, ATA100 here...) by noticing the actual failed
> > device in
> > /proc/mdstat, then running smartctl -a /dev/hde (my device)
> > so I knew
> > which model/serial number I needed to pull.
>
> Are you saying you run RAID with even one disk to be able to use software
> RAID monitoring tools?
>
> >
> > RJ
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-- 
-Joseph Brinkley
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