Gordon Henderson schrieb:
On Tue, 15 May 2007, Tomasz Chmielewski wrote:
I have a RAID-10 setup of four 400 GB HDDs. As the data grows by
several GBs a day, I want to migrate it somehow to RAID-5 on separate
disks in a separate machine.
Which would be easy, if I didn't have to do it online, without
stopping any services.
M1 - machine 1, RAID-10
M2 - machine 2, RAID-5
My first idea was to copy the data with rsync two or three times
(because the files change, I would stop the services for the last run)
- which turned out to be totally unrealistic - I started rsync process
two days ago, and it still calculates files to be copied (over 100
million files, with hardlinks etc.).
I have recent experience of copying up to 1TB parititions to offsite
backup servers via rsync (and a 10Mb line), and it can be done.
You do need a recent version of rsync and a lot of memory in both
servers. I'm really surprised it takes days to do this on your server -
although maybe the source server really is busy?
Yes, the server is really busy and reads/writes a lot - that's one. Two,
it's being done over iSCSI in a pretty complicated scenario:
100 Mbit
M1 (RAID-10 storage) <--> very busy virtual machine in Xen
/
/ 1 Gbit
/
machine with rsync process <--> M2 (RAID-5 storage)
1 Gbit
So there is a slow point of just 100 Mbit to access the storage, which
is normally fully filled anyway.
rsync, even 3.0, just doesn't fit here - it has to be done in sort of a
"mirror" way.
--
Tomasz Chmielewski
htp://wpkg.org
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