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#11
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Scott Lurndal wrote:
FTP is hardly a useful benchmark for determining the peak ethernet performance anyway. Try with something lower overhead like rcp. Huh? Once you've gotten past the dialog that starts the transfer, ftp has no level 3 overhead: it sends just data bytes until EOF. -Joe |
#12
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"J. Clarke" wrote in message ...
You might want to check the CompUSA site--they were having a deal for 200 gig drives for about 90 bucks counting a mail-in rebate, but I don't know if it's still on. The last time I saw one of these rebates, it was limited to one per household unfortunately. * Accordingly, get a HighPoint SATA RAID card instead of the specified RocketRAID 454 ATA RAID card. I think the RocketRAID 1640 Personally for a RAID that size I'd go for a 3Ware or LSI Logic. No particular reason, just that I'm used to terabytes being mainframe territory and I get nervous with consumer RAID controllers trying to handle that much data. I think, from the link he mentioned, that he intends to use the Linux md driver. (software RAID). Most of those cheap RAID cards are not hardware RAID at all. They advertise it falsely and give you a Windows driver that does software RAID. Nothing is worse than cheap RAID. If you're not using something solid, even if it does really do hardware RAID, your best bet is software RAID. The Linux software RAID is better-tested and more widely used (by people who will notice if something went wrong and get it fixed or at least complain) than any of the cheapo RAID or fakeraid cards. Bigger issues than the size of the RAID group are things like, what happens if a drive fails? This can be very hard to test without special HD firmware made for this purpose. I've seen cheap hardware RAIDs where yanking the drive out seems to fail it fine, but when a drive fails for real, the errors get passed through to the OS. Or how does the RAID behave when running into bad blocks on a "good" drive, while resyncing onto a hot-spare or a replaced disk. I've seen even hugely expensive "enterprise" solutions fail miserably here. Or how does the RAID behave when it sees a double-disk failure? Even some high-end solutions give you no way to recover. Obviously if both drives have really failed, you're screwed. But what if a power connection gets knocked loose? |
#13
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) wrote in alt.video.ptv.tivo:
Or how does the RAID behave when it sees a double-disk failure? Even some high-end solutions give you no way to recover. Obviously if both drives have really failed, you're screwed. But what if a power connection gets knocked loose? I had this exact situation with Linux software RAID-5 (2.6 kernel), and a simple remove and re-add of the drives caused the re-build to start, and I lost no data. I'm trying to figure out how to get a spare onto the array to avoid even this sort of problem, but although the software can do it, I don't have any more room in the case. -- Jeff Rife | SPAM bait: | http://www.nabs.net/Cartoons/UserFri...munication.gif | | |
#14
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#15
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"Jeff Rife" wrote in message
... ) wrote in alt.video.ptv.tivo: Or how does the RAID behave when it sees a double-disk failure? Even some high-end solutions give you no way to recover. Obviously if both drives have really failed, you're screwed. But what if a power connection gets knocked loose? I had this exact situation with Linux software RAID-5 (2.6 kernel), and a simple remove and re-add of the drives caused the re-build to start, and I lost no data. I'm trying to figure out how to get a spare onto the array to avoid even this sort of problem, but although the software can do it, I don't have any more room in the case. If you are going to do software RAID on the 2.6 kernel anyway, why not check into RAID6(?) that is supposed to have the equiv of two parity drive? This is something I am going to look into soon. -- Angel R. Rivera aka Wolf ---------------------------------------------------------------- Please post all reponses to UseNet. All email cheerfully and automagically routed to Dave Null |
#16
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Will Dormann wrote:
I'm doing a cheap-o scaled down version of what you describe. As soon as my drives come in I'll let you know. I have a feeling that the latency will be increased when seeking through a recording, but other than that might be OK. Ok, I've got my NAS machine set up and it works quite well. I figured I'd share my notes if anybody's interested. Here's the description of the machine: AMD K6-III 450 256MB RAM 3x Samsung 120GB IDE drives Cheap SiI0680 IDE controller Cheap 100Mb NIC (Realtek 8139) Gentoo Linux using kernel 2.6.7 BOOT ext3 on RAID1 with hot spare ROOT xfs on RAID1 with hot spare STORE xfs on RAID5 Gentoo 2004.2 wouldn't recognize the 0680 IDE controller on boot. I could modprobe the module for it and it seemed to be detected ok according to dmesg. But I could not access any of the attached drives. Perhaps I missed something other than doing the modprobe to make the drives accessible? So I used Gentoo 2004.1 and that worked fine. I had to manually modprobe the 8139too module, but after that the networking was fine. When using the Gentoo Live CD, the system was stable. But after installation and booting from the hard drives, it was not. It would often hang on drive access, giving "Lost Interrupt" errors for the devices on the SiI0680. This was with both 2.4 and 2.6 kernels. I finally tracked it down to a BIOS setting for the PCI interrupt. It was set to "Edge", but changing it to "Level" fixed the problem. Why I didn't see any issues when booting from the live CD, I'm not sure... Originally I had the ROOT and STORE partitions set up as JFS. Perhaps caused by the couple of system hangs, the ROOT partition got corrupt. The symptoms I noticed were that the filesystem would seem to randomly switch to read-only mode, requiring me to reboot. In the kernel log were the errors: Aug 14 15:15:51 [kernel] ERROR: (device md2): stack overrun in dtSearch! Aug 14 15:15:51 [kernel] btstack dump: Aug 14 15:15:51 [kernel] bn = 0, index = 0 - Last output repeated 6 times - Aug 14 15:15:51 [kernel] bn = cffdc960c015dcfb, index = 208 I ran jfs_fsck and forced it to scan the whole filesystem, but that didn't cause the above issue to disappear. Figuring that jfs wasn't quite ready for prime time, I decided to switch to xfs instead. Using the gentoo live CD and my "hot spare" drive, I copied the contents of the ROOT partition, formatted md2 with xfs, and then copied the contents back. Now, how it works.... The K6-III 450 works fine for this purpose, at 100Mbit ethernet speeds. I don't think I'd want anything slower, though. I'm currently copying over my MythTV recordings (very large files) via NFS and the CPU usage is around 60%. Almost 10% of this is from the md3_raid5 process, and the rest is nfsd. When copying over files from my windows machine via Samba, the CPU usage was around 40% I believe. I haven't done any special tuning or benchmarking, so I'm not sure if NFS is less efficient than Samba, or if it's just moving the data faster. The machine works great as a MythTV store. I see no latency problems at all when skipping back and forth through a recording. And the MythTV machine will probably run cooler now due to the decrease in disk activity. I currently have it set up to have the "live" TV buffer on the local disk, and the recording on the NAS. In the setup for MythTV, the settings for these two locations are separate, which is cool. Now, I wonder how long it'll be before I fill it up! At least the price was right, with the total out-of-pocket cost being about $250 -WD |
#17
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Will Dormann wrote:
I'm currently copying over my MythTV recordings (very large files) via NFS and the CPU usage is around 60%. Almost 10% of this is from the md3_raid5 process, and the rest is nfsd. When copying over files from my windows machine via Samba, the CPU usage was around 40% I believe. I haven't done any special tuning or benchmarking, so I'm not sure if NFS is less efficient than Samba, or if it's just moving the data faster. I'm doing some copying of similar files over Samba now, and the CPU usage is between 60% and 70%. So it appears that NFS and Samba are pretty close, CPU-wise. -WD |
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