Re: A few remaining questions about installing to RAID-10

[Ben DJ <bendj095124367913213465@gmail.com>]

Hi Robin,

On Fri, Oct 2, 2009 at 10:01 AM, Robin Hill <robin@robinhill.me.uk> wrote:
> Depends really - far isn't much slower on writes (the I/O elevator and
> filesystem buffering help).  If you know /var will be write-mostly (it's
> often the default location for MySQL data files as well) then a near
> layout may be better though.

Ok, that's clear.  /var is typically a mix, it seems.  I may well
create a second set of partitions for read-write on /data & /var/cache
(I already put /tmp in tmpfs/RAM. /home I've mixed feeling about) --
once I've convinced myself that the benefits really show up in the
benchmarks.  And decide whether it's worth the complexity.   And, of
course, then the which FS to use decisions (would prefer ZFS, but n/a.
 brtfs is promising but still experimental afaict.  ext4 &/or xfs may
be my solutions); but that's for a different ML, I guess.

> RAID-1 over N disks can survive N-1 drive failures.  Each disk holds a full copy of the data.

I really need to stop confusing RAID-0/1 mirrors & stripes.  THanks.

> Currently only RAID-1,4,5 and 6 support growing arrays (by either adding
> spindles or increasing the capacity of each spindle).  There are plans
> to add this capability to other RAID levels but I'm not sure where this
> sits on the priority list.

Good to know.  With 4x1TB drives, I've got 2TB RAID-10 space to play
with.  More than enough without worrying about the expansion too much.
 For now.

Thanks.

Ben
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