Date: Tue, 29 Sep 2015 20:21:59 +0200 From: InterNetX - Juergen Gotteswinter <jg@internetx.com> To: Michael Fuckner <michael@fuckner.net>, Graham Allan <allan@physics.umn.edu>, =?UTF-8?Q?Karli_Sj=c3=b6berg?= <karli.sjoberg@slu.se>, "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: Cannot replace broken hard drive with LSI HBA Message-ID: <560AD6C7.80800@internetx.com> In-Reply-To: <560AD2B9.5040706@fuckner.net> References: <1443447383.5271.66.camel@data-b104.adm.slu.se> <5609578E.1050606@physics.umn.edu> <560A4640.3030200@internetx.com> <560A9461.8090300@physics.umn.edu> <560A977C.1070102@internetx.com> <560AD2B9.5040706@fuckner.net>
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Am 29.09.2015 um 20:04 schrieb Michael Fuckner: > On 9/29/2015 3:51 PM, InterNetX - Juergen Gotteswinter wrote: >> From my Experience using SATA Disks on SAS Controllers, no matter if >> theres an Expander between or not or mixed, those Setups keep on beeing >> flakey / unreliable. I might work under certain conditions, but its >> nothing you can bet on. >> >> Garret Damore (Illumos Project) describes the problem more detailed here >> >> http://garrett.damore.org/2010/08/why-sas-sata-is-not-such-great-idea.html >> >> > > come on, the article is 5 years old, some things changed since then! > > - MUX Boards are unreliable and expensive- long time since I last saw > those boards i am not talking about sata multiplexers, i am talking about sas expanders. no one ever should think that sata multiplexers are a reliable piece of hardware. they arent. this problems are design related, since Natacount on disks cant talk native with sas controllers. they still exist and occour. like you can see here. a few months ago i had a setup which had exactly what one whould expect from sata/sas mix. bus resets, device hangs and so on. in the end, it turned out that the indel dcs 3500 ssd wich where connected via a lsi sas 2008 where the root cause of all. after they where hooked onto the onboard sata ports, everything was fine. on the other side the intel dcs 3700 sata ssd works fine in sas/sata mix. you see, its nothing you can count on. stay with sas, or with sata and use proper controllers. except you like hunting server gremlins > - SAS Disks are not just 10/15k high performance Disks anymore, most > Nearline Disks are available with native SAS interface as well nearline sas disks are equipped with a real sas interface, they just work with less rpm. > - if you pick the right disk there is no trouble using SATA Disks on SAS > Expanders or SAS Controllers (they should have R/V sensors, optimized > FW...). yes, but still russian roulette with data > - if you use desktop drives in a shelf with lets say 24 slots you should > not expect it to work ;-) well, depends on the usecase, controllers and cabling. look at backblaze... > > Regards, > Michael!
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