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    SubjectRe: SATA-performance: Linux vs. FreeBSD
    Date
    Am Dienstag, 13. Februar 2007 12:25 schrieben Sie:
    > > Well they do. The Flash disk I have (SATA-I) is capable of 48 MB/s and
    this
    > > value is reached over the whole disk size by windows as well as by
    FreeBSD.
    > > See my test results in the first thread.
    >
    > Ok a flash disk should be more stable
    >
    > > My Seagate Barracuda Harddisk drive (SATA-II) starts with 76 MB/s and
    > > decreases linearly to 35 MB/s due to the fact that it has to write to a
    > > rotating disk. But on a flash disk there is nothing rotating...
    >
    > The hard disk one isn't guaranteed or stable but the flash especially if
    > it is aimed at it ought to behave.
    >
    > > So where is the difference between SATA-I and SATA-II ?
    >
    > All physical side if they are on the same controller when you do the
    > tests. Mostly latency,
    >
    > > And why is FreeBSD able to write with constant rates (the complete 25 GB,
    all
    > > with 48+/-0.1 MB/s) but Linux 2.6.18 not ?
    >
    > Does the FreeBSD fsync sync to media ? Also what controller is being used
    > here, and do you have EHCI USB support running ?
    Manual of FreeBSD fsync says it syncs to media.

    I used the same controller: Same computer, same harddisk. two partitions on
    the system disk, one for linux, one for freebsd.

    EHCI:

    ehci_hcd 0000:00:1d.7: EHCI Host Controller
    ehci_hcd 0000:00:1d.7: USB 2.0 started, EHCI 1.00, driver 10 Dec 2004
    usb usb1: Product: EHCI Host Controller

    AHCI

    ahci 0000:00:1f.2: AHCI 0001.0100 32 slots 4 ports 3 Gbps 0xf impl SATA mode

    >
    > > With a dedicated (rotating) SATA II device, using the first 70% of disk
    space
    > > no problem -- tested ! With a SATA-I device only a problem with Linux
    2.6.18
    >
    > I suspect the SATA-1 itself may not be the decider but something else -
    > eg the hard disk using NCQ, which would cover up any latency related
    > problems.
    >
    > > Journaling of data: you are right, ext2 performs better than ext3.
    >
    > And ext3 in writeback mode ought in theory (but practice is always
    > harder ;)) be faster than ext2.
    >
    >

    --
    Dipl. Physiker
    Martin Anton Fink
    Max Planck Institute for extraterrestrial Physics
    Giessenbachstrasse
    85741 Garching
    Germany
    Tel. +49-(0)89-30000-3645
    Fax. +49-(0)89-30000-3569
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