Date: Sun, 16 Nov 2014 19:49:55 -0500 From: Mike Tancsa <mike@sentex.net> To: FreeBSD Hackers <freebsd-hackers@freebsd.org> Subject: Re: OT-ish SATA port replicators vs. SAS "expanders" Message-ID: <54694633.7000906@sentex.net> In-Reply-To: <CAJm4238NDHV_uzertrrcce9kwFwyKoYY6pO5E58s-2DoZkwm-w@mail.gmail.com> References: <CACpH0Me7Y%2Bm6cENsg2otcP9agDp%2BwKPGnPxDafFfySPNkhsKBA@mail.gmail.com> <CAJm423_%2B5wL4G48ftVOmmkyyjSpekS3=sv801pyquRkqcz=fTQ@mail.gmail.com> <CACpH0MdfzpTXceHnRkAo60ztu4Bo%2BbKSpOYZJyV6goY0Q0TbUg@mail.gmail.com> <54693866.9040009@sentex.net> <CAJm4238NDHV_uzertrrcce9kwFwyKoYY6pO5E58s-2DoZkwm-w@mail.gmail.com>
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On 11/16/2014 7:26 PM, Brandon Vincent wrote: > On Sun, Nov 16, 2014 at 4:51 PM, Mike Tancsa <mike@sentex.net> wrote: >> I don think a port multiplier is the same as a SAS expander and a SAS/SATA >> controller does not necessarily support port multipliers. > > You're absolutely correct. The SATA specifications if I recall > correctly, outline that providing support for port multipliers is > optional. Not to mention, the vast majority of chipsets that do have > support for port multipliers only provide the slower command-based > switching method [1], The LSI SAS 2008 chipset is not what you > typically find on the cheap consumer "fake RAID" cards which most > people have [2]. > > Most people who purchase this card are purchasing it for SAS, true > RAID, performance, and reliability. Thus, LSI is only going to provide > support for the far superior SAS expander technology. We also got rid of all those external 4 port PMs and replaced it with one NORCO RPC-4220 The pricing is quite reasonable and less expensive then using PMs and so far MUCH more reliable. ---Mike -- ------------------- Mike Tancsa, tel +1 519 651 3400 Sentex Communications, mike@sentex.net Providing Internet services since 1994 www.sentex.net Cambridge, Ontario Canada http://www.tancsa.com/
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