Date: Fri, 18 Jan 2013 14:42:51 -0800 From: Matthew Jacob <mj@feral.com> To: freebsd-hackers@freebsd.org Subject: Re: IBM blade server abysmal disk write performances Message-ID: <50F9CFEB.5060302@feral.com> In-Reply-To: <1358544287.32417.251.camel@revolution.hippie.lan> References: <CAA3ZYrBV9f%2BcHx4jvS0UKTr%2Bp7eNUBA0S2%2Bv9oZAHqwm9VBOWw@mail.gmail.com> <6C0B86E6-195C-4D35-AE40-3D2F9F6D28FB@yahoo.com> <alpine.BSF.2.00.1301182217590.1478@wojtek.tensor.gdynia.pl> <1358544287.32417.251.camel@revolution.hippie.lan>
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This is all turning into a bikeshed discussion. As far as I can tell, the basic original question was why a *SAS* (not a SATA) drive was not performing as well as expected based upon experiences with Linux. I still don't know whether reads or writes were being used for dd. This morning, I ran a fio test with a single threaded read component and a multithreaded write component to see if there were differences. All I had connected to my MPT system were ATA drives (Seagate 500GBs) and I'm remote now and won't be back until Sunday to put one of my 'good' SAS drives (140 GB Seagates, i.e., real SAS 15K RPM drives, not "fat SATA" bs drives). The numbers were pretty much the same for both FreeBSD and Linux. In fact, FreeBSD was slightly faster. I won't report the exact numbers right now, but only mention this as a piece of information that at least in my case the differences between the OS platform involved is negligible. This would, at least in my case, rule out issues based upon different platform access methods and different drivers. All of this other discussion, about WCE and what not is nice, but for all intents and purposes it serves could be moved to *-advocacy.
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