Re: Question about IDE configuration...
- From: tony@xxxxxxxxxxxxxxxxxxx (Tony Mountifield)
- Date: Mon, 10 Jul 2006 15:24:00 +0000 (UTC)
Jim, thanks for the comments!
In article <e8t7un$rgo$1$830fa7a5@xxxxxxxxxxxxxxxx>,
Jim Howes <sewoh.mij@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Tony Mountifield wrote:
I will be building a system with two IDE hard drives and an IDE CDROM,
connected to the standard two IDE ports. The system will be running
Linux, and the two identical hard drives will be set up as a RAID-1
mirror (so will both be active together-ish). The CDROM will only be
used for installation and upgrades (this is an industrial system).
You have various options for RAID configuration. LVM + software RAID works, but
using it for the boot drive tends to cause it to spend a lot of time re-syncing
after boot time. If the system is up more-or-less permanently this is not a
problem. Using RAID only for user data partitions has been more successful here.
I've successfully built several systems like this before, using software RAID
without LVM, under FC3 and CentOS 4, so that part of it I am quite happy with.
Once the system has been up long enough for the initial sync to finish, then
it doesn't need to resync on rebooting. But the system will be up all the time
anyway.
On the previous systems, I had put both HDs on the Primary IDE, but was
beginning to wonder whether they would be better on separate busses, hence
my posting the question here.
The downside of (a) is that I had heard a slow device like a CD on the
same IDE cable as a fast hard drive can cause the HD to be slower.
Is that correct or not?
Anything that supports UDMA, which anything remotely recent does, makes this
point entirely moot. The 'slowest device' rule does not apply unless one of the
devices does not support UDMA.
OK, I'll check the CDROM for that specifically, but it sounds promising.
The downside of (b) is that only one hard drive can use the Primary
bus at a time. Would the hard drives be able to overlap operations
if I used configuration (a)?
Most drives only have a sustained data transfer rate of around 65Mbytes/sec
(Seagate ATA-5 drives). Bear in mind that 'UDMA-133' is more marketing spin
than actual transfer rate.
Serial-ATA (and SATA-II) will get you better bandwidth, at around 76Mbytes/sec
sustained per channel, and interface cards are cheap.
I must explore SATA sometime, but for this box I'll stick with standard ATA.
Cheers
Tony
--
Tony Mountifield
Work: tony@xxxxxxxxxxxxx - http://www.softins.co.uk
Play: tony@xxxxxxxxxxxxxxx - http://tony.mountifield.org
.
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- From: Tony Mountifield
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