12 messages in com.ubuntu.lists.ubuntu-ukRe: [ubuntu-uk] RAID 1 with three drives| From | Sent On | Attachments |
|---|---|---|
| Rob Beard | Mar 2, 2009 2:40 am | |
| Tony Travis | Mar 2, 2009 2:47 am | |
| Rob Beard | Mar 2, 2009 3:34 am | |
| Alan Pope | Mar 2, 2009 3:42 am | |
| Andrew Oakley | Mar 2, 2009 4:18 am | |
| Alan Pope | Mar 2, 2009 4:31 am | |
| Samuel Toogood | Mar 2, 2009 4:32 am | |
| Andrew Oakley | Mar 2, 2009 4:39 am | |
| Rob Beard | Mar 2, 2009 5:51 am | |
| Rob Beard | Mar 2, 2009 5:53 am | |
| Alan Pope | Mar 2, 2009 6:03 am | |
| Rob Beard | Mar 2, 2009 6:20 am |
| Subject: | Re: [ubuntu-uk] RAID 1 with three drives | |
|---|---|---|
| From: | Andrew Oakley (Andr...@hesa.ac.uk) | |
| Date: | Mar 2, 2009 4:18:35 am | |
| List: | com.ubuntu.lists.ubuntu-uk | |
Alan Pope wrote:
"mdadm"
Yus.
Of course as soon as you add the disk back into the array you're going to cause a boatload of IO as the array resyncs from the internal disks back out to the external one, and that's going to happen _every_ time you plug the disk(s) in.
I've used Linux Software RAID 1 for more than five years now, and you're absolutely right that a re-sync does indeed cause a boatload of IO, unavoidably, every time. For upwards of twenty minutes or more, in many cases.
However it was also been my experience that this has little or negligable impact on the responsiveness of the desktop system. Linux multi-tasks REALLY well.
The only time I've noticed it - other than the HD LED flashing and the disk being a bit noisy - was when I tried to do something else really, really IO intensive at the same time, such as moving several hundred gigs of data about whilst the resync was underway (eg. copying a movie to a different filesystem). Then, that process runs slow.
Andrew Oakley Head of Software Development Higher Education Statistics Agency (HESA) 95 Promenade, Cheltenham, Gloucestershire GL50 1HZ T 01242 211460 F 01242 211122 W www.hesa.ac.uk
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