Re: RAID-5 vs. Disk Mirroring
Date: 1996/01/29
Message-ID: <4eh0og$ree_at_widow.nla.gov.au>#1/1
> RAID-5 vs. Disk Mirroring
...snip
> We are trying to make a decision on a direction. The concern is which
> method will ensure that data will be there (no loss is permited),
> while not comprimising performance. Cost is not a consideration.
READ or WRITE performance ?
Both RAID-5 and disk mirroring impact badly on WRITE performance and have comparable READ performance gains over single disks.
If you go RAID-5 then make sure you have additional disks sitting idle in the RAID-5 cabinet and that the hardware can do a soft-swap of any bad disk with one of the idle ones so you never have the configuration operating without a parity disk if one should fail. Make sure the RAID-5 controller(s) have LOTS OF CACHE; this helps aleviate the WRITE performance degradation.
For maximum performance and reliability you can have 2 or 3 member disk mirrors and then use disk striping to get back some of the WRITE performance you lose. Again, have several spare disks available so you can add and remove disks from the mirror set when needed.
I found reference to RAID-7 which is proprietry and looks interesting
have a look at http://www.storage.com
Bruce... Received on Mon Jan 29 1996 - 00:00:00 CET