Re: Does A8N-SLI Deluxe have Raid 5 online expansion?

In article <1132705347.003366.15840@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
idon.wong@xxxxxxxxx wrote:

> Thanks guys.
>
> My plan is to build a new machine to act as my home office server which
> would operate 24/7. Since it is going to be on all the time anyways, i
> figured i might as well make it my network file server too, rather than
> buy a seperate NFS like Buffalo's solution. Since it'd mostly be
> hosting media content (like photos, movies, music), for read
> operations, i thought the Raid 5 CPU hit might be ok (plus i'd have a
> dual core CPU). I'd have another set of drives (possibly mirrored) for
> the other applications to run (and write) off of. That raises another
> question - am I able to enable both raid controllers at the same time?
>
> Anyways, here are the specs I've got planned. Any thoughts?
>
> AMD Athlon 64 X2 3800+
> Asus A8N-SLI Deluxe
> OCZ PC3200 DDR400 Premier Series 1 Gb Dual Channel
> Asus GeForce 6200 128MB PCI-E
> Antec SLK3800B Mid Tower w 400W PSU
> 4x Western Digital SATA 320GB drives
> 2x Seagate ATA 200Gb (I have kicking around)
> DVD+/-RW drive
>
> My original question was aimed at whether i can save a few bucks now,
> not buy 1/4 320 Gb drives now, and add it later. Does the XP hack
> support expansion?
>
> Thanks,
> iDon

I don't do RAID myself, as I only have desktop configs for
computers, but some questions I'll ask anyway...

1) What is your backup strategy ? Any time you plan on buying
a whack of disks, with a large total capacity, do you plan
on using that capacity ? Can you predict how many years it
will take to fill it ? Is there any point going with 320GB
drives ?

2) If you have a backup strategy capable of dealing with the
sum total of storage capacity you plan on the new machine,
then in-place migration becomes a non-issue. Simply backup
and restore. Your backup solution should be capable of
backing up the whole array, in an overnight time period
(say 8 hours, so you are not bumping into the backup the
next day). If the backup method was sector-by-sector,
no compression, and a disk managed 50MB/sec transfer
speed, then in 8 hours you can transfer 1.44 Terabytes.
That implies the backup solution itself doesn't have to
be striped to work. File by file backup wouldn't be
practical if your large array was full, but makes sense
if the array is mostly empty (seek time is a killer on
backups, as is softwqre compression).

This is one reason you won't find any big drives in my house,
because it would cost too much to back them up. Each computer
gets a tiny drive, with a tiny backup requirement. An 80 GB
drive, with a second 80GB drive as a cold backup device, is
enough for me.

No matter how a RAID is constructed, the disks are all connected
to the same power supply, and are sitting in the same ATX
metal box. A catastrophy, like a lightning blast, or a PSU
failure that overvolts all the drives, will negate whatever
redundancy is in the RAID array. That means, even if you
bought a $600 RAID card, added hot spares etc., your array
could still be destroyed in a millisecond.

Tape is too expensive to make a decent backup method. Using
disks is an alternative, but a proper rotation strategy would
require more disk drives than you would be happy with. DVDs
would probably be too slow in backup or restore, to meet
an eight hour objective.

I think your first engineering task, is figuring out how
backups will work. Constructing the RAID array will seem
trivial after that.

Yes, you can run more than one array at a time on your board.

Maybe a smaller array, with more emphasis on off-line
storage of stale content, would make more sense. You could
probably afford to buy smaller disks, and make your RAID
a reality today. Say 4 x 80GB plus a single 320GB disk to
do a backup. That should have a reasonable starting price.

You might also benefit from an external drive tray
mechanism, to make inserting the backup drive easier.
There are devices that have a small shell to hold the drive,
which is then inserted into a drive bay. A second solution
is to pick up a cheap SATA controller card, with an ESATA
external port connector. That will allow transfers that are
not limited by the performance of the cable (as would be the
case with a USB2 or Firewire 400 enclosure for an external
drive). It means the external enclosure needs no bridge
board - just a power supply plus the SATA drive.

http://store.yahoo.com/cooldrives/saingrsisadr.html

Paul
.

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