Slow HDD performance

  • Hi,

    New to open media vault, I have an old tranquil BBS which has I believe has a silicon image sil3124 Sata card in it. It’s a sata ii card supposed to be capable of 3Gbps

    I had a 2tb drive and recently bought 2x4tb and 1x2tb to fill the other slots (os drive is a 180gb intel ssd). My planning was to have mirrored 4tb as my music server drive and the two 2tb as my family/photo/docs drive.

    Anyway I started last night creating the raid array on the 2tb drives and it’s performance was 40MB per second and took almost 12 hours at a guess. Today I did same for the two brand new 4tb drives and again it’s max write speed is 40MB/s. This speed seems very slow and being both sets of drives are seeing same write speed I am beginning to think it’s a config/driver issue for the sata card.

    Anyone got any thoughts on if 40MB/s is actually reasonable for setting up the array and if not what I can do to potentially sort the issue.

    Formatting the 2tb array didn’t seem to take too long (maybe 20min) I can take exact time from 4tb one when it’s ready tonight or tomorrow.

    Many thanks


  • Hi John,

    did you consider to read in the forum posts?

    omv 5.6.9-1 (usul) on RPi4/4GB with Kernel 5.10.17 and WittyPi 3 V2 RTC HAT

    2x 6TB HDD formatted with ext4 in Icy Box IB-RD3662-C31 / hardware supported RAID1

    For Read/Write performance of SMB shares hosted on this hardware see forum here

  • Yes I did consider reading and done a few searches here and generally in google but couldn’t find much except examples of how long arrays take to set up (though most seem to use much faster speeds for hdd write to estimate time to finish).

    I am happy with my choice of 2 sets of mirrored drives for moment.

  • No I haven’t used mdadm before but looking about 40MB/sec seemed slow for creating a mirrored array in software. But if answer is it’s not that slow then I am happy. Enquiry answered. Mainly trying to find out if that’s reasonable and only if it isn’t try and figure out why it’s slow.

  • I think your issue may be related more to the rpm of each drive and the fact that it's sata II, the unfortunate thing is not being able to test a single rather than a raid

    Raid is not a backup! Would you go skydiving without a parachute?

  • On speed tests the 4tb 5400rpm drives I have show avg sustained write speed of 145MB/sec so is there a reason it should be so low as 39-42MB/sec building a mirror raid?

    Surely even sata II shouldn’t be constraining it that badly.

    Like I say just wondering really

  • Surely even sata II shouldn’t be constraining it that badly

    TBH that coupled with the 5400 drives is the only logical explanation, another way to have achieved this, was to use single drives, then use the second as backup using rsync. Rsync can be done overnight and timings set according, in essence it's giving the same outcome as a mirror but without the overhead of the data being written to both drives as the same time.

    Raid is not a backup! Would you go skydiving without a parachute?

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