Windows 7 software raid problems...

Discussion in 'Windows 7 Help and Support' started by Hawq, Jan 30, 2011.

  1. Hawq

    Hawq New Member

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    Hi.

    First, sorry for long post but I want to give you as much details as possible before asking my questions :)

    I've two 1 TB disk running in raid 1 (2 partitions, both mirrored) under Windows 7 Ultimate. Its clean install on new computer. System was installed on single disk and then both disk were converted to dynamic and mirror was added. It took about 4h 30m to synchronize array which means that sync speed was around 61 MB/s. Drive was already holding large amount of data when mirror was created.

    Yesterday I saw first BSOD after 1.5 year of using Windows 7 on various machines :) Computer usually shows login prompt in less than a minute, but booting to login prompt after BSOD took over 10 minutes due to really heavy disk activity. After logging in and launching disk manager (which took another 10 minutes) I saw that both mirrors were resyncing... in parallel. Computer was hardly usable. It was taking half a minute to just move mouse pointer to desired location not to mention at least 5-10 minutes waiting for web browser to launch.

    Because I needed my system usable in matter of minutes I did following:

    1. Opened PC case, disconnected secondary SATA drive.
    2. Booted to Windows, raid arrays got marked as degraded.
    3. Shutdown PC, reconnected SATA drive.
    4. Booted to Windows again, dropped mirroring.
    5. Recreated mirroing, one partition at a time.

    And this is were my problems started. It took over 4 hours to resync system partiton (100 GB), and second partiton is still resyncing. Currently it is resynced in 35% after 14 hours which gives resync speed around 6 MB/sec. Its ten times slower than first array creation.

    So here are my questions:

    1. Opening PC and disconnecting the drive isn't nice way to get system usable after each unclean system shutdown. Is it possible to force Windows to synchronize just one array at time? I couldn't find any setting for this and parallel raid synchronization is simply unacceptable.

    2. What may have caused such slowdown in synchronization speed? 6 MB/sec isn't normal tranfer rate and its clearly system problem as it was over 60 MB/s during first mirror creation and no changes were made in hardware/software configuration.
     
  2. Hawq

    Hawq New Member

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    FYI, I gave up AHCI and switched back to IDE mode after AHCI BIOS was hanging on detecting one of drives after I've repartitioned it. I had to clear all partition from it to have it detected again. Most likely bug in BIOS.

    System now runs fine and disk performance seems a lot better than in AHCI. Whole 1 TB disk was resynced in software raid in 3 hours and 15 minutes. It means that transfer rate was around 84 MB/s. Nice speed up!

    The only things that are still causing problem are SATA DVD drives connected directly to mainboard. They like to hang when trying to read. I've just switched to external USB drive and all problems are gone. At least for now ;-)

    From what I've read on the net similar problems are quite common for at least few Gigabyte mainboards. Some of them have BIOS updates fixing those issues, but other does not so be carefull with Gigabyte hardware and AHCI mode. Especially avoid it on GA-H55N-USB3 or you may run into same problems I had.
     
  3. SeptimusFry

    SeptimusFry Senior Member

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    Just discovered this thread: I am in same situation.
    • found that my 1.5TB mirror set was resynching constantly, system very sluggish
    • ran HDTune on the two disks and found one was able to respond at around 100MB/s, the other at around 6MB/s (call this disk M2).
    • Thinking that M2 was defective, I broke the mirror set by removing M2 and did tests on it, which showed it to be apparently OK.
    • Put them back into mirror, now resynching at around 6MB/s, and has been doing so for hours. Currently, new writes happen at about 80MB/s whilst resynching, but they are clearly going to M1 whilst M2 is playing catchup. All reading is being done from M1.
    • I am using perfmon to see what is happening, looking at physical disk, read b/s and write b/s for each of the two mirror members.
    I really need to understand Hawq's second posting, as it may have the key to my problem as well. It is worth mentioning that I have an Asus M/B, P6TD, not Gigabyte.
     
    Len likes this.
  4. Len

    Len Member

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    This is the first real clue I've found on fixing the terrible performance of mirrored drives in Windows 7. Some motherboards have Sata 2 an Sata 3 interfaces so a mix-match can cause a real problem. I've been watching Windows sycnh since 7 AM. I'm just letting it run so I can remove the final mirror. It's so slow I could beat it with a pencil, but I will examine the AHCI/IDE issue and determine the interface disparity, once I have complete control.

    After a lot of testing here I decided Acronis is junk, and that there are two good ways to keep backups.

    The easiest way is synchronicity which is free on sourceforge. I removed most of my mirrored partitions and just run synchronicity on a schedule. It is similar to rsync (if you know linux) and VERY FAST. In about 5 minutes all of my drives have duplicate content verified. You can configure it so it only adds to the target if you want, so older versions stay intact.

    Another program I've found useful is Winzip from Corel. It does more than just duplicate content, you can manage archives etc, and unlike Acronis you don't have a broken TSR running.

    Then for real backups, just clone your system drive on a regular schedule. So far, although I've had drive crashes, I've survived them easily and was back on line in only a few minutes.

    Drive cloning with a cartridge enclosure is definitely the best backup system with large hard drives. Just keep more than one copy of the system drive, and plug one in every day let it dupe overnight and shut down. Simple, effective, and it works. I recovered from a metal crash in 15 minutes last month - with a screwdriver. For really robust data backups put your data on Dropbox and buy the version control upgrade. They now allow up to 1 Tb of data, and the time machine add on is amazing when something goes wrong. Had to use it once, and it took about 10 minutes to get a file reverted.

    The Mirror solution is cute, but poorly implemented, contains no brainy suggestions when it should detect an issue that will degrade performance or integrity, and is not really supported - which means Microsoft will be dumping it soon. I thought of developing a system service to do it right, but got so frustrated with MSDN, I decided its not worth my effort to wade through the marketing types and actually do anything. I seriously do not understand how Microsoft can do this kind of thing over and over, and my only guess is the managers are overwhelmed with marketing people telling them what to do - or none of them speak English well enough to really understand what needs to be done. Anyway, my strategy works without mirroring. I'm at 85% resynched, and soon all mirrors will be history.
     

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