The Belgain

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  1. The Belgain

    3-drive Linux software RAID5 performance

    Well, I've added the 4th drive to my array now, and the results I'm seeing are below. This is now a RAID5 array of 4 320GB WD SATA drives. james@ubuntu-fileserver:~$ bonnie -d raid5array/bonnie/ Writing with putc()...done Writing intelligently...done Rewriting...done Reading with getc()...done Reading intelligently...done start 'em...done...done...done... Create files in sequential order...done. Stat files in sequential order...done. Delete files in sequential order...done. Create files in random order...done. Stat files in random order...done. Delete files in random order...done. Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP ubuntu-fileserve 1G 29971 83 58920 13 20682 6 26587 70 86801 17 259.6 0 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 2815 97 +++++ +++ +++++ +++ 2935 98 +++++ +++ 9034 99 ubuntu-fileserver,1G,29971,83,58920,13,20682,6,26587,70,86801,17,259.6,0,16,2815,97,+++++,+++,+++++,+++,2935,98,+++++,+++,9034,99 I'll rerun with the -s parameter to see if the results differ very much.
  2. Well... looks like two fairly differing opinions then. On a related note, are there any cheapish PCI-E 1x 4-port (or more) SATA controllers out yet? I can't seem to find any...
  3. Hi there, I've currently got a 4-drive RAID5 Linux software RAID5 setup, and am going to be adding an extra drive for capacity. I don't have any spare SATA ports, and need to get a hard drive with an external enclosure for a while. I was hoping to expand the array to a 5-drive RAID5 array with this drive (using EVMS). Is this going to work OK, or am I just asking for trouble? How bad is the performance likely to get? Will I hit issues with the drive dropping in and out of the array for example? Is firewire a better choice than USB2 (I'll probably get an enclosure with both, and my motherboard has both)?
  4. The Belgain

    3-drive Linux software RAID5 performance

    Yeah I was pretty puzzled about that too, but is this just bonnie being a little confusing about it's output? Is it talking about input and output to the program rather than the drive (so that the left figures are writes and the right figures are reads)? Yes I've run it multiple times, on an idle system. The results are very consistent between runs.
  5. Hi there, I've just set up a Linux sofware RAID5 array, and was wondering whether the performance numbers I'm seeing are about right or a bit low? I had two 320GB drives and 2 160GB drives so I've RAID0'ed the 160s and created a "3-drive" raid5 from that and the 320s. The 320s are WDs, and the 160s are Maxtor DM9s (all SATA). They're running on the onboard ICH6 SATA controller, CPU is a 2.4GHz P4. Bonnie gives the following: james@ubuntu-fileserver:~$ bonnie -d /home/james/raid5array/bonnie Writing with putc()...done Writing intelligently...done Rewriting...done Reading with getc()...done Reading intelligently...done start 'em...done...done...done... Create files in sequential order...done. Stat files in sequential order...done. Delete files in sequential order...done. Create files in random order...done. Stat files in random order...done. Delete files in random order...done. Version 1.03 ------Sequential Output------ --Sequential Input- --Random- -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- --Seeks-- Machine Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP /sec %CP ubuntu-fileserve 1G 29959 82 54596 11 21789 7 28181 73 73167 15 281.6 1 ------Sequential Create------ --------Random Create-------- -Create-- --Read--- -Delete-- -Create-- --Read--- -Delete-- files /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP /sec %CP 16 2687 96 +++++ +++ +++++ +++ 2798 97 +++++ +++ 8841 99 ubuntu-fileserver,1G,29959,82,54596,11,21789,7,28181,73,73167,15,281.6,1,16,2687,96,+++++,+++,+++++,+++,2798,97,+++++,+++,8841,99
  6. Hi there, I'm looking into getting some hotswap drive racks for my SATA drives. Supermicro do a 5-in-3 SATA hotswap drive rack (link) which seems quite nice. The thing I'm slightly concerned about is cooling: there's just a single 90mm fan blowing over the 5 drives, and the drives are very tightly packed (5x 3.5" drives vertically in 3x 5.25" bays). Has anyone got any experience with these Supermicro racks, and do the drives stay cool enough? Also, regarding future SATA standards (eg. SATA2, and the next ones), do the drive racks limit you to a particular one, or do they just do electrical passthrough and nothing cleverer? Does anyone know af any cheaper hotswap racks than this one (4-in-3 or 5-in-3)? The Supermicro seems to be almost $200, which is pretty steep...
  7. The Belgain

    linux file server

    There's loads of distros that are pretty good for people without much Linux experience. I'm using Ubuntu at the moment, which is a very nice distro (getting more and more popular) and easy to start with. And it comes with EVMS pre-configured for handling RAID etc.. Fedora's pretty nice too...
  8. Apologies if this has been asked before, but I've just got a quick query about choosing stripe-sizes for my RAID-array. I'll putting together a RAID5 array with the following drives: 4x 160GB, 2x 320GB I'll be doing it by creating two 320GB RAID0 arrays from the 160s, and then creating a 4-drive RAID5 array from these two arrays plus the 320GB drives. Now intuitively it seems to me like it would be a good idea to choose the stripe-size for the RAID0 array to be half the stripe-size of the RAID5 array? So that a chunk of the RAID5 array splits up into exactly one chunk for each drive in the RAID0 array. Is this correct? Also, what stripe-size would be good for a fileserver which will just be used for storing files, and streaming audio/video over a LAN (so STR is what I'd like to optimise). I was thinking 32KB for the RAID0 arrays, and 64KB for the RAID5 array?
  9. The Belgain

    Which filesystem?

    Thanks for the replies guys. I think I'll probably just be sticking with EXT3 as it's pretty tried and tested. I don't know how justified they are, but there seem to be many posts about data corruption on Reiser and some other filesystems, so I'll stay away from them...
  10. The Belgain

    Which filesystem?

    Hi there, I'm putting together a large software RAID5 array, and was just wondering what filesystem I should use? I'm using EVMS to manage it, and this is on an Ubuntu Breezy install; all the main filesystems are available on it (EXT3, Reiser, JFS, XFS, ...). I'm not really that bothered (within reason) about performace as this is just going to be accessed over a network - mainly for streaming audio/video. What I do need however is: - stability: I want to be as sure as possible that there's no chance of data corruption occuring. - it's got to be possible to expand the filesystem while keeping the data on it intact (I don't need it to be able to do this while mounted though). - ideally it should be possilbe to have very large partitions on it (it'll be only 1TB for now, but could conceivably become > 2TB). At the moment I'm thinking that plain old EXT3 may be best (especially for stability). Am I right in thinking the maximum size of the array is ((2^32) * chunk_size)?
  11. The Belgain

    Non-striping RAID4

    Hi there, I've recently come accross this thread in AVSForums about a new (to me at least) way of implementing RAID4 with slightly different aims to standard RAID4/5. Like RAID4, an n-drive array has a single dedicated parity drive, which stores XOR parity data for the n-1 drives and protect against loss of data when any single drive in the array fails. The difference is that rather than data being striped accross drives as in RAID4/5, each drive appears as a completely serparate drive to the OS, and data is written to a single drive (plus the parity drive). So when data needs to be read from a drive, it is simply read exactly as if the drive were a single drive. When data is written to one of the drives in the array, the existing data is first read from the drive and if the new data differs, then the parity data on the parity drive is reversed, otherwise it is left unchanged. The obvious disadvantage of not striping the data is that performance is significantly worse than a traditional RAID4/5 array; read performance is at most 2x the speed of a single drive, and write performance is slower than that of a single drive. The advantage and main reason for this method is flexibility; drives don't have to be the same size (the only requirement is that the parity drive is at least as large as each other drive in the array). Also it's very easy to expand the array (to add a drive, all that needs to be done is to add the drive to the array, and then recalculate the data on the parity drive - recalculating parity isn't even necessary if the drive is added formatted to a 0's!). Similarly it's very easy to remove drives, or swap drives out for larger/smaller ones. The reason I noticed this is that it's being offered by a company called Limetech. They are offering it as a slimmed-down Linux distro with a RAID driver they've written themselves, and a managment interface. They've announced that they're going to release the code for the driver module under the GPL. It seems like it would be really nice to have this functionality in the Linux software RAID kernel module. Does anything like this exist already? If so, then why has it never caught on (the video buffs with the 1000's of DVD seem pretty keen on the idea of just being able to add redundant storage without any hassle or having to worry about getting identical-sized drives)? I was wondering if anyone has any experience using a similar system before? Is this new?
  12. The Belgain

    Raid 5, just not worth the money?

    Software RAID5 on Linux is cheap...
  13. The Belgain

    Nested Linux software RAID arrays

    This is true, but that's also the case of the other setup suggested... EVMS lets you do this and it's supposed to be pretty stable I gather... doing a full backup of 500GB just isn't really feasible unfortunately... I'd say about 70% of it is backed up to DVDRs though... Yeah, that's what I'm most worried about... Ubuntu comes with EVMS installed and configured by default (even though it isn't completely upto date in terms of revisions), so I may just give that a go...
  14. The Belgain

    Nested Linux software RAID arrays

    Also, I'm a little new to compiling and installing new kernels; I'm planning on using Ubuntu, and upgrading it to use the latest 2.6.13 kernel (it comes with 2.6.10 installed I think). Are there going to be any issues with following the guide at ?
  15. The Belgain

    Nested Linux software RAID arrays

    Oh really? That's making me a little nervous now... I'd have thought nested RAID arrays would have been pretty common, especially for things like RAID10 or RAID50?