Re: HDD vs. RAID (was Re: Lilo Q)
hi ya
fun stuff..... it depends ...
if you have a nearly full 80GB disks ... it wont matter
if you have 1x 80GB or 4x 20GB( stripping )
- i rather worry about 1 large disk failure... than to worry about
which of the 4 small disks gonna die ... also makes 4x the mess
in power and cables...etc..
if you use raid1 ( mirroring ) .... effective usage is 1/2 of the
total raw disk space
- not useful if you're using 40gb of data on your 80gb disks
- good option if you want to protect up to 40GB of data from
disk crashes and want to stay online even if a single disk crashes
as was suggested earlier... use raid5 instead..
if 4 disks raid5 ... if any one disk dies.. you can still recover
( effective disk space is 60GB out of 80gb )
if you add a 5th 20GB disks... you still have 80gb out of 100GB of
total usable space.... still only protected against one disk
failure
but any of the 4 or 5 disks could die ... instead of one 80gb disk
== if read transfer speed is important.. use raid0 ( stripping ) over
raid1 ( mirror )
- you should be able to read data 2x as fast...
but writing is a little slower...
best best...
===
=== backup data regularly to DIFFERENT systems ..
===
c ya
alvin
-- original bios/disk question ...
- most BIOS can and does support up to 130GB or so w/o any
problems
160GB ata 133 being the tricky disks to play with
- most mb cannot boot from hde/hdf/hdg/hdh
- so tell lilo to write mbr info to hda and
that / is still /dev/hde ... works fine ...
On Sun, 9 Jun 2002, Dave Sherohman wrote:
> On Sun, Jun 09, 2002 at 09:35:05AM -0400, Ian D. Stewart wrote:
...
> > (say, 80 GB hard drive vs. raid tower w/ 4 20 GB hard
> > drives) ?
>
> If you're getting 80G from 4*20G drive, that must be a RAID 0, so
> the RAID would give you a nice boost to data transfer rates, but
> you'd better keep a current backup because if any one of those 4
> drives goes bad, you'll lose all your data. (OTOH, add a fifth 20G
> drive, make it a RAID 5, and you'll have a winner.)
>
> Side note: Comments on performance assume that each drive is on a
> separate IDE channel all by itself. If your 4 20G drives are hda,
> hdb, hdc, and hdd, you're going to take a major performance hit.
> Unlike SCSI, IDE can't run two drives efficiently on the same
> channel.
>
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