Re: IDE versus SCSI

"Dusan Bolek" <pagesflames_at_usa.net> wrote in message news:1e8276d6.0201100719.1ac3c868_at_posting.google.com...

> Maybe. And maybe it also has something with no IDE drives in
> cataloques of spare and upgrade parts for UNIX servers or external
> storage boxes.

With proprietary hardware, you have no choice in what you have (although you do have a choice of which arm and leg you sell to pay for it)

> Wake up ! Everything runs on SCSI.

Not disputed - the discussion is about why. Just because everyone does something doesn't make it always and every time the right thing to do (see C++ for an example).

> For medium sized database I need about 300 gigs of space.
I would hazard a guess that the vast majority of production databases in use are considerably smaller than 100GB if only because a 100GB database was considered large until relatively recently. Also consider just how little data is required for operational (transactional) non-datawarehouse systems e.g. personnel, finance, factory operations.

> How will I get this size with IDE ? Using four IDE positions and fill them
with 4x120GB Western Digital drives ?
Asked and answered.

> However I need a RAID array, because I have to have a redundancy in case
of disk failure.
You can, of course fit a second controller should you need to, which will get you to 8 drives which is as much as there are empty bays in most intel based servers.

Nor do you NEED redundancy. It is essential for the redo logs to prevent data loss, but for anything else, you are trading off cash against the risk of an hour or two's downtime a year to replace and restore a failed drive. You are explicitly banned from using Oracle in safety critical systems where it might matter.

> Can I use an ATA RAID controller for PC workstation ? That's nonsense.
We're talking about database servers.
The label is irrelevant, merely the performance and reliability requirements of the particular application.

> Database servers are running Unix, has RAID1 or combination of RAID1
> and RAID5 arrays. I've never seen an UNIX box with IDE. Of course,
> with exception of some low end Linux servers.
See proprietary hardware above.
My local DBA keeps trying to get us to pay £40,000 to move a database from NT to UNIX. At the end of which we'll have the same database we have now. There have been problems with the NT box, almost all of which are down to incompetent sysadmins and lack of disk space (which could be fixed for £300). Many people are simply snobbish about the use of UNIX.

> RAID5 is not about (or not only) performance. You need an array because
you can't loose your precious data.
see redundancy above

> You can't live with four devices in database server.
I am not aware of lethal consequences.

> The biggest advantage of SCSI is that their controller has its own
> logic to handle data transfer. IDE drive gives a lot of work to your
> CPUs and I think that we have better work for our CPUs than handle
> disks.

IDE drives at maximum throughput take less than 5% CPU. Frankly on most servers, the CPUs spend most of their time idling - you really don't have better work for them to be doing. Received on Fri Jan 11 2002 - 03:11:55 CST