RAID 1 question

[stevech]

Prices down, motivation up. I bought two 500GB SATA II drives today, and an el-cheapo PCI bus two-channel RAID-1 (Silicon Image 3512) controller. Old motherboard; no PCIe. Fumbled around a while, it seems to be setup and working. Two partitions: 50G for small files and the rest at 64K blocks for video. I guess the RAID doesn't know about partitions or file systems or block sizes, but rather just mirrors disk sectors.

So this thing has been "synching" the drives for hours now, I guess it decided to dupe one disk to the other.

When it's done, is there any way to ensure there *is* a mirror? I suppose I could take each drive out of the RAID and read it separately. Must be a better way. No blinky LEDs to watch.

[scoful]

You can disconnect one drive at a time - you should see the same data on each of them.

There should be a RAID utility that shows the members of the set and their state. I have used several of the SIIG cards using the Silicon Graphics chipset and haven't had a problem.

[stevech]

thanks.

Do you know what triggers the RAID controller to re-synch the drives?

If I disconnect one, then reboot, don't write any files, will Windows none the less write something that causes the RAID to resynch?

The first synch seemed to copy 100% of one disk to the other. Took many hours. I guess it doesn't know which sectors have been altered on the source disk. Don't want to trigger that full resynch again!

I'm a RAID noob.

[mattdcknsn]

I am not familiar with Silicon Graphics chipsets but for RAID if the power is on and you disconnect a drive as soon as you reconnect it the array HAS to rebuild. You might not modify any files that you know of but during the normal boot process files get date stamps changed, pagefile changes, a lot of files change behind the scenes. Another thing that might cause a rebuild is a drive is dying and it cant keep up, I have seen some where the power supply isn't adequate so a drive randomly goes offline. Anything that can cause data to be missed can cause a rebuild.

It depends on the RAID card and the interface used (IDE, SATA, SCSI, SAS) as to how fast the rebuilds go. I wouldn't recommend disconnecting a drive regularly to move some data. If you want to use it as a backup system it is usually faster to have the rebuild go from the RAID card BIOS and not in the OS. (It is different than the computer's BIOS). Usually the RAID card limits itself during rebuilds while the OS is running so you can still use the computer. When its in the BIOS it may not have this restriction.

Originally Posted by stevech

thanks.

Do you know what triggers the RAID controller to re-synch the drives?

If I disconnect one, then reboot, don't write any files, will Windows none the less write something that causes the RAID to resynch?

The first synch seemed to copy 100% of one disk to the other. Took many hours. I guess it doesn't know which sectors have been altered on the source disk. Don't want to trigger that full resynch again!

I'm a RAID noob.

[opy01]

I have that same Sil3512 card. You should be able to set up the RAID in the cards bios which is what I would recomend. If you mirror the drives it should write the data to both cards at the same time so it shouldnt need to re-sync. Mirroing the drives should show absolutely no perfomance difference at all (thats why I am going with RAID3).

Matt has a good point about the hard drive dying or the power supply maybe too small or failing. I have a hard drive that shuts off all the time and I reboot and its on again because my power supply is old and too small and I am running 5-6 drives and 6 or more fans in the system. I actually see that all the time on other PCs also.

[stevech]

thanks. This is my first RAID so stupid me and questions.
That 3512 chip on the PCI card (I know, it's slow) seems to work. I reconnected the drive and it began to copy the other drive to the one I unplugged. That's being done totally in the BIOS, I guess, since I see no CPU activity. The SATAraid software that came from Silicon Image's website is not very good. Its help file is dated 2004 and doesn't match the GUI. The PDF user manual is a different date and GUI look.

It takes 8 hours or so to rebuild a 500GB disk. I wonder what happens if I unplug the "good" drive and power up, then down, then re-plug. I thus disrupted the rebuild. Perhaps I just ignores this as it would not let Windows access the incompletely rebuilt drive. The docs don't discuss this.

It was hard to find an "old" PCI bus card for SATA RAID 1. The RAID status software is not very good and I'd probably choose to pay more for a better card next time. I didn't want to spend $200 or a RAID 1 card for this old mobo. The software does seem to work but is crude.

I sure do like the concept of automatic backup of everything. I'd been using SecondCopy for selected directories, and TruImage for the full disk. But this 2 x 500GB should let me put all my data on it. Family photos, videos (2nd partition), and so on.

Another surprise I had was the power supply for this PC. I bought a new 500W PS with SATA connectors. With both 500GB drives powered by one cable, the drives often will not spin up at power on. Splitting the drives to two cables cures this. Must be a crappy PS design. I read that some RAID controllers stagger the drive spin-ups to stop power demand peaks.

[nyle]

Originally Posted by stevech

thanks. This is my first RAID so stupid me and questions.
It takes 8 hours or so to rebuild a 500GB disk. I wonder what happens if I unplug the "good" drive and power up, then down, then re-plug. I thus disrupted the rebuild. Perhaps I just ignores this as it would not let Windows access the incompletely rebuilt drive. The docs don't discuss this.

It was hard to find an "old" PCI bus card for SATA RAID 1. The RAID status software is not very good and I'd probably choose to pay more for a better card next time. I didn't want to spend $200 or a RAID 1 card for this old mobo. The software does seem to work but is crude.

I've had good luck with Promise's software RAID controllers for Windows. (The low end ones) The more expensive cards use hardware to accelerate the process. I only had two 100GB drives mirrored at the time but it never took 1/5 of 8 hours to mirror. Is your processor really low end?

The idea of RAID is that if one drive fails the data is still accessible so when it is mirroring(you say syncing) to the other drive to make sure their CRCs are the same you can still access the data on the disk that it doesn't think has failed/been replaced.

I still recommend that you back up your data to something else. If a file becomes corrupt on the system, guess what will happen? It'll be corrupt on the mirrored drive as well. ;^) It'd be a good idea to back up key data to another location using the software you mention. Especially, Acronis that's some great software.

You probably could have just bought a new MB with RAID support built on for not much more money but I'm not sure what processor you have. Still there are a lot of MBs that support SATA RAID right on the MB now.

It sounds like you've got it working the BIOS and software should tell you if it's mirrored successfully. Since I know you'll still follow my backup advice, even if something goes wrong with the mirror you'll still be all set.

-Nyle

[stevech]

Originally Posted by nyle

I've had good luck with Promise's software RAID controllers for Windows. (The low end ones) The more expensive cards use hardware to accelerate the process. I only had two 100GB drives mirrored at the time but it never took 1/5 of 8 hours to mirror. Is your processor really low end?

The idea of RAID is that if one drive fails the data is still accessible so when it is mirroring(you say syncing) to the other drive to make sure their CRCs are the same you can still access the data on the disk that it doesn't think has failed/been replaced.

I still recommend that you back up your data to something else. If a file becomes corrupt on the system, guess what will happen? It'll be corrupt on the mirrored drive as well. ;^) It'd be a good idea to back up key data to another location using the software you mention. Especially, Acronis that's some great software.

You probably could have just bought a new MB with RAID support built on for not much more money but I'm not sure what processor you have. Still there are a lot of MBs that support SATA RAID right on the MB now.

It sounds like you've got it working the BIOS and software should tell you if it's mirrored successfully. Since I know you'll still follow my backup advice, even if something goes wrong with the mirror you'll still be all set.

-Nyle

thanks. For file corruption, I do now and will continue to dupe certain files to a USB2 drive using SecondCopy automatically. Really important ones get encrypted and duped to an Internet site that I trust will be there 3 years from now.

EDIT: so I have 500GB drives. Rebuild = read then write, maybe not overlapped. I think it pauses as well to permit routine I/O to the healthy drive. If the net speed were 20MB/sec (read then write), this would be 500GB/20MB = 7 hours.

The rebuild is sure slow, for 500GB drives. The Windows Perf Monitor says the CPU is idle 99%. The CPU is an AMD2400. I guess the BIOS on the SATA RAID card somehow gets Windows to call it every now and then. I don't know the concept of how the BIOS gets CPU time. Maybe it's just a thread in the RAID device driver in Windows? Any idea on how to speed this up?

Is it true that there is no management software other than what I have (from Silicon Image) for the 3512 SATA RAID board (Google didn't find any)?

I thought about replacing this old Socket A AMD2400 motherboard. But I'd need a new CPU and new DDR memory. It all adds up. About 2 months ago I did this same cycle for my main office PC (ASUS M2N-MX, AMD 4200+ dual core, DDR2 6400) and am very happy. But it was like $300+.

[opy01]

Thats on the low end for replacing CPU, MB and Mem. You will be lucky if you can use the same video card as well. You will actually come out ahead if you get one with a SATA RAID built in though and it will come with decent software too. You may want to look for a MB that has hot-swapable SATA ports so if one drive dies then you unplug it and plug the new one in and rebuild without even powering down. The rebuild should be no slower than if you were copying all the data to a new drive from scratch and that depends on your write speed and amount of data. Glad you got your power issue figured out. I think thats what my problem may be as well (besides cheap old PS), I have 2 HDs on one cable along with 3 cooling fans .

[stevech]

I've been fooling with the old AMD2400 socket A plus a SiL 3512 RAID card and two 500GB disks. Raid works; two partitions, one for video.

Then I got the bright idea to make the RAID bootable. After a lot of missteps in the BIOS setup (I reflashed the BIOS too). Suddenly it decided to boot the Windows I installed on the RAID. All is fine. Until...

I reconnected the IDE drive. The BIOS apparently has no way for me to force it to boot from the RAID in priority to the IDE hard disk. The BIOS doesn't know about RAID. I have to choose DISABLE for all drives except the CD, and ENABLE the "OTHER" boot device. But when the IDE hard disk is present, the "OTHER" choice picks it, not the RAID.

Reading the forums, others report this on various motherboards, to include some that are much newer than mine. One fellow says that this doesn't happen if the lone (non-RAID) drive is SATA instead of IDE.

No doubt, some BIOS gets it right. No way for me to know.

[opy01]

I beleive you should be able to set that in the boot.ini on the IDE (non RAID)drive. your current one should look similar to this

multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect

you will need to add a line right below it that says this

multi(0)disk(0)rdisk(1)partition(1)\WINDOWS="Microsoft Windows XP Professional"

you may want to change the name to distinguish between OSs

I know the primary IDE drive, when there is one, is the multi(0)disk(0)rdisk(0)partition(1) and if you dual boot into the second partition its multi(0)disk(0)rdisk(0)partition(2). If there is no IDE partition then the first drive available is multi(0)disk(0)rdisk(0)partition(1). When there is an IDE drive present make sure the boot.ini is on that drive and the RAID drive should be multi(0)disk(0)rdisk(1)partition(1) or multi(0)disk(1)rdisk(0)partition(1). Also be sure to set the timeout to 30 seconds.

If this conpletely confused you I appologise, it can be quite confusing.

The other thing you can do is install windows on the raid after the IDE drive with an OS is present and windows should set up the multiboot for you, sometimes.

[stevech]

I think I accidentally got the boot from RAID while IDE is present problem fixed. No where written, it seems that this Socket A BIOS will skip booting the IDE drive if its cable is connected as an IDE secondary drive. Weird. BIOS Boot order says HDD0 to HDD3 are DISALBED, and BOOT OTHER is ENABLED. But it still boots the IDE if it is connected as an IDE Primary. Doesn't boot it if the IDE is SECONDARY.

Geeze.

I also downloaded an upgrade to my Acronis Disk Director/OS Selector software (good stuff, as is TruImage). This new Disk Director allows you to choose any partition on any disk on the PC to boot from. That works too. I'd prefer not to use that, but it is a way to boot the RAID with the IDE as PRIMARY on the cable. So when you do this Disk Director approach, you set the default to be the RAID drive. The IDE gets booted bringing in the Disk Director software which then boots Windows from the RAID.

I think I'll leave the IDE as SECONDARY. I haven't tried the IDE as PRIMARY on the *second* IDE channel to see if this dumb BIOS boots that even if told not to. Doggone BIOSes don't document all this behavior. It's time wasting trial and error.

Anyway- this is my first time with Bootable Windows on a RAID 1. I have Windows in a 50GB partition and 416GB as video, in 64K blocks. This will be neat - full automatic protection from drive failures which are when, not if.