building a RAID system - 8 drives

Alvin Oga alvin at Mail.Linux-Consulting.com
Thu Oct 9 06:13:21 EDT 2003


On Thu, 9 Oct 2003, Trent Piepho wrote:

> On Thu, 9 Oct 2003, Alvin Oga wrote:
> > > > backup is hard.  you can get 160 or 200G tapes, but they're almost 
> > > > as expensive as IDE disks, not to mention the little matter of a 
> > > 
> > > 100GB LTO tapes can be had for $36, that's less than half the price of the
> > > cheapest 200 GB drives. 
> > 
> > we/i like to build systems that backup 1TB or 2TB per 1U server ...
> >  	- tapes doesn't come close ... different ballpark 
> 
> How do you stick 2TB in a 1 U server?  I've seen 1U cases with four IDE bays,
> and the largest IDE drive I've seen is 250 GB.

8 drives ... 250GB or 300GB each ..

> I've got two 4U rackmount systems sitting side by side on the same shelf.  One
> is a ADIC Scalar 24, which holds 24 100 GB LTO tapes.  The other is a 16 drive
> server with 200GB SATA drives and two 8 port 3ware cards.  The tape library
> has 2.4 TB and the IDE server is 3.2 TB.  To be fair, the IDE server is brand
> new, while the ADIC is around a year old.  If the tape library were bought
> today, it would have a LTO-2 drive with double the capacity and could store
> 4.8 TB.  So tapes seem to come pretty close to me.  It also quite a bit more
> practical changes tapes with the library than to be swapping hard drives

nobody swaps disks around ... unless one is using those 5.25" drive bay
thingies in which case ... thats a different ball game 

i/we claim that if the drives fail, something is wrong ... its not
necessary for the disks to be removable 

> around.  The libraries built in barcode reader keeps track of them all for me. 
> I can type a command and have it spit out all the tapes that a certain set of
> backups are on.  They fit nicely in a box in their plastic cases and if I drop
> one it will be ok.  I can stick them on a shelf for five years and still

i prefer hands off backups and restore .... esp if the machine is not
within your hands reach ...

> expect to read them.  And the tapes don't take up any rackspace or power or
> need any cooling.  I've never had a tape go bad on me either, even though I've
> been though a lot more of them than IDE drives.
> 
> Of course the tape library was expensive.  A new LTO-2 model can be had for
> around $11,600 on pricewatch.  The 16 bay IDE case, CPUs/MB/memory and 3ware

for $11.6K ... i can build two 2TB servers or more ...
	8 * $400 --> $3200 in drives  ... for 2.4TB each ...  
		 + $700 for misc cpu/mem/1u case
		and it'd be 2 live backups of the primary 2TB system
		or about 2-3 months of weekly full backups depending ondata

> controllers were much less.  But the cost of the media is a lot less for
tapes
> than for SATA hard drives.  Especially if you get models with 3 year
> warranties.  Once you buy enough drives/tapes you'll break even on a $/GB
> comparison.

i dont want to be baby sitting tapes ... on a daily basis and cleaning its
heads  or assume that someone else did

c ya
alvin 

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