On Thu, Oct 30, 2008 at 8:02 AM, Per Jessen
Greg Freemyer wrote:
All,
I'm conceptually putting together a NFS server in my head. (I will build it once I know what it is!!)
What I want is something flexible.
ie. Have it start with 3 or 4 drives, then add a drive when I need the capacity. Remove a drive when I don't. replace the drives with bigger drives as the become available. All without losing my data. (Or having to back it up / restore it.)
My first thought - LVM.
I'm very familiar with LVM. It does not really do the same things as RAID. Not even if you only worry about the performance side of things. ie. a 4 disk raid system is faster than a single disk for most raid setups. With LVM based on 4-drives, it is typically just the same speed as a single disk.
I'd like to start with a 4 disk Raid 10 providing 2 TB of space, but then have the ability to add disks, change raid techniques etc. (ie. convert to raid 6 without data loss!!).
mdadm --grow implies it can do this, but there is not much there and my google searches did not turn up much either.
I don't think mdadm --grow can do what you want. It's very useful when you for instance want to build a RAID1 in degraded mode (with only one drive), and you later want to add a drive to bring it back to full RAID1. You can probably also add a drive to working RAID1 or maybe even RAID5, but I don't know.
The man page says it can change the "size or shape" of a raid array. But then provides no detail. :( I'm assuming shape means the raid level? Not a phrase I know in reference to raid.
And can it be used to "shrink" a volume. (I believe XFS supports shrinking a filesystem, so I would first shrink the filesystem, then hopefully use mdadm to shrink the raid array.)
Most advanced filesystems (jfs,xfs,ext3 et al) support resizing - otherwise the LVM resizing features wouldnt be overly useful :-)
I know most can grow. iirc, only xfs can shrink?
If mdadm can't do any of this, is there a hardware controller card that can?
Take a good look at LVM.
Actually I came across the QNAP TS509 yesterday. A very cool NAS that seems to do everthing I want. It is Linux based and provides ssh access. I assume you can use that access to admin things if need be. Its about $1000 for an empty shell that holds 5-drives. Greg
-- /Per Jessen, Zürich
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-- Greg Freemyer Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer First 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.pdf The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org For additional commands, e-mail: opensuse+help@opensuse.org