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Re: [ProgSoc] iSCSI - the new I in RAID?



On 22/08/2007, at 11:05 PM, jedd wrote:

 I have a situation that, I think, is crying out for iSCSI -- I need
 a lot of very cheap disk that can be accessed by a number of
 boxes at reasonable speeds.

 Most of the figures I can find for iSCSI put it at about the same
 price as FC connected SANs, which I tend to think blows badly.

 Our encumbent brand (HP) for example thinks that a bunch of
 300GB FC disks at $1500 plugged into a retro-fitted iSCSI SAN
 box is a good idea.  Whereas I tend to think that $120,000 for
 6TB isn't a good idea.

(Is it just me and them, or do all the big players flog disks at three
 times the price of the yum cha shops, and compound the problem by
 offering a 1year warranty compared to the lifetime warranty I'm
 getting on WD/Samsung/etc?)

 Anyhoo, back to iSCSI -- pointers, warnings, recommended vendors,
etc gladly received. Mind, I have entertained the idea of a plenty big
 server running GNU/Linux, but would rather something applianceish.
Depends on what performance you need and what 'reasonable means'

Cache, channels, spindles, latency, interdisk access speeds, redundancy, capacity are what seems to matter here.
We just got a Hitachi AMS500 for our web farm.
Specs:
8Gb Cache
6TB of usable FC Disks (RAID-6 on 90x 144Gb 15K drives incl hotswap) [With 4Gbps interdisk communications speed]
2TB of usable SATA (RAID-6 on 10x 250Gb 7.2K drives incl hotswap)
So in total we have 8TB of usable online storage.
Automatic LUN failover and assumption by the backup controller, redundant PSU and controllers on the SANbox
The SAN has 4x 4Gbps FC ports with 2x links going to each of 2x FC  
switches. Each of our 4x Servers has 2x connections to each FC switch.
http://www.hds.com/assets/pdf/hitachi-tagmastore-adaptable-modular- 
storage-model-ams500.pdf
We paid less than what you're looking at.

We looked at iSCSI but the throughput we needed exceeded what iSCSI could really do for us. That and UECOMM has some beautiful multiprotocol fibre broadband product called WDM that gives you your WAN link on one splice and Fibre Channel replication over another.
Cheers,

-Andi

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