Date: Sat, 19 Jun 2010 20:53:35 -0600 From: Scott Long <scottl@samsco.org> To: oizs <oizs@freemail.hu> Cc: freebsd-current@freebsd.org Subject: Re: Dell Perc 5/i Performance issues Message-ID: <2F904ED8-BC95-459F-8536-A889ADDA8D31@samsco.org> In-Reply-To: <4C1C0ED9.8090103@freemail.hu> References: <4C1AB4C0.4020604@freemail.hu> <A594C946-32C0-4C4A-AA37-0E81D270162A@mac.com> <4C1B3792.9000007@freemail.hu> <AANLkTimsHZLREByndqXEjt2yjdvOYVV7Rnw8AMjqxYIl@mail.gmail.com> <4C1C0ED9.8090103@freemail.hu>
next in thread | previous in thread | raw e-mail | index | archive | help
Two big things can affect RAID-5 performance: 1. Battery backup. If you don't have a working battery attached to the = card, it will turn off the write-back cache, no matter what you do. = Check this. If you're unsure, use the mfiutil tool that I added to = FreeBSD a few months ago and send me the output. 2. Partition alignment. If you're using classic MBR slices, everything = gets misaligned by 63 sectors, making it impossible for the controller = to optimize both reads and writes. If the array is used for secondary = storage, simply don't use an MBR scheme. If it's used for primary = storage, try using GPT instead and setting up your partitions so that = they are aligned to large power-of-2 boundaries. Scott On Jun 18, 2010, at 6:27 PM, oizs wrote: > Im using the Samsung F3 disks, which can do 140MB/s sequentially. I = have tried different raids raid0 will do just as bad as raid5. I even = tried one disk which performed as expected 100MB/s+ reads and writes so = I'm not sure anymore what could be the problem. Maybe the controller = hates samsung disks? >=20 > -zsozso >=20 > On 2010.06.19. 0:21, krad wrote: >> On 18 June 2010 10:08, oizs<oizs@freemail.hu> wrote: >>=20 >>=20 >>> I've seen people with the same configuration doing 160MB/s writes = and >>> 250MB/s+ reads with raid5 so I still think something isn't right. = And using >>> raid10 with 4 disks is a rather large waste of capacity. >>>=20 >>> -zsozso >>>=20 >>>=20 >>> On 2010.06.18. 1:55, Chuck Swiger wrote: >>>=20 >>>=20 >>>> On Jun 17, 2010, at 4:50 PM, oizs wrote: >>>>=20 >>>>=20 >>>>=20 >>>>> I've bought a Dell Perc 5/i because I couldn't make the onboard = marvell >>>>> 88sx7042 work with 8.0/8.1 or current, but as lucky as I am, the = best I can >>>>> do with 4x1.5tb samsung in raid5 is 60MB/s writes and 90MB/s = reads, with >>>>> bbu/write-back/adaptive-read-ahead. >>>>>=20 >>>>> I was expecting at least twice of that, and I'm not sure what can = I do to >>>>> get that speed. (I've read man 7 tuning with no success) >>>>>=20 >>>>>=20 >>>>>=20 >>>> Switch to using RAID-10 rather than RAID-5. It's normal for RAID-5 = to >>>> have worse write performance than that of a single drive. >>>>=20 >>>> Regards, >>>>=20 >>>>=20 >>>>=20 >>> _______________________________________________ >>> freebsd-current@freebsd.org mailing list >>> http://lists.freebsd.org/mailman/listinfo/freebsd-current >>> To unsubscribe, send any mail to = "freebsd-current-unsubscribe@freebsd.org" >>>=20 >>>=20 >> what are your drives though? Are they SATA green/eco type drives or = proper >> SAS enterprise ones >> _______________________________________________ >> freebsd-current@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-current >> To unsubscribe, send any mail to = "freebsd-current-unsubscribe@freebsd.org" >>=20 >>=20 >>=20 > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to = "freebsd-current-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?2F904ED8-BC95-459F-8536-A889ADDA8D31>