How to choose the right iSCSI switch
I've written a few times about the many unexpected complexities involved in getting an IP storage network to work optimally. Whether you're using NFS or iSCSI, it's not surprising that the switches you choose -- and how you configure them -- can make an enormous difference in both the performance and reliability you can expect to achieve.
Though 10Gbps Ethernet is becoming far less expensive than it once was, you'll still pay a substantial premium for it in comparison with 1Gbps Ethernet. This cost rears its head not only in the switches, but also in items as simple as cabling; even twin-ax direct-attached copper cables run around $150 each, a fair sight more expensive than a $5 CAT5e cable. For enterprises seeking the high bandwidths and simplicity that 10GbE can offer, it can be an excellent and entirely worthwhile investment, but most of us simply don't need it yet.
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That's why the vast majority of IP-based storage implementations use garden-variety 1Gbps Ethernet technology and rely upon multipath I/O or link aggregation to achieve performance in excess of 1Gbps. Though it's absolutely true you can use general-purpose networking gear for IP storage, not all 1Gbps Ethernet switches are well-suited to handling the loads associated with IP storage. Here are a few guidelines you can use to grade your options if you find yourself on the hunt.