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maybe broken SD card
by Russell Coker 26 Apr '13

26 Apr '13

Recently the micro SD card in my Samsung Galaxy S3 stopped working. As I wasn't sure whether the card or the phone was broken I tried connecting it to my Thinkpad T61 running Debian/Unstable. It gave the following log entries when I inserted the card (in a holder to make it fit the full size SD socket in the Thinkpad). Is this proof that the micro SD card is broken? I will of course try other cards in the phone (which needs more storage) and try the card in another phone (it probably has data I want to keep). But I lack enough hardware to be sure that there isn't some strange partial compatability issue. Apr 25 20:03:30 linux kernel: [ 599.446191] mmc0: error -110 whilst initialising SD card Apr 25 20:03:30 linux kernel: [ 599.449766] sdhci-pci 0000:15:00.2: Will use DMA mode even though HW doesn't fully claim to support it. Apr 25 20:03:30 linux kernel: [ 599.514728] sdhci-pci 0000:15:00.2: Will use DMA mode even though HW doesn't fully claim to support it. Apr 25 20:03:30 linux kernel: [ 599.584550] sdhci-pci 0000:15:00.2: Will use DMA mode even though HW doesn't fully claim to support it. Apr 25 20:03:30 linux kernel: [ 599.659497] sdhci-pci 0000:15:00.2: Will use DMA mode even though HW doesn't fully claim to support it. As an aside, where can I get a cheap micro SD card? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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Re: [luv-talk] New Computer System
by Russell Coker 24 Apr '13

24 Apr '13

On Mon, 22 Apr 2013, Craig Sanders <cas(a)taz.net.au> wrote: > if your m/b takes DDR2 RAM then it' still possible that upgrading RAM > alone may be enough, but it's a bigger gamble....if it doesn't work, > you'll just be throwing the money away unless you have a use for a 2nd > computer after you buy a new one. DDR2 is pretty much obsolete, and > more expensive than newer DDR3 - 4GB of DDR2 costs $56. Of course if they are going to keep using the old system then upgrading the RAM won't be such a waste. Having a second PC is a really good idea for anyone who's serious about a computer hobby and it could also be given to a friend or relative. > Alternatively, if you do go for a new system with an i7 CPU, you may > find that the built-in Intel GPU is good enough - they're low-end if > you're a gamer, but more than adequate for video playing, and they have > good open source drivers. My experience of Intel video cards is that they are quite good for playing video with the free Linux drivers. So far the only time I've found a built-in Intel video controller to be inadequate for my use (which is occasional video playing and other tasks that aren't particularly challenging - I'm not a serious gamer) is when I got a monitor with a resolution higher than FullHD. > The FX-8350 @ $209 is $100 cheaper than the i7-3770, and a decent AM3 > motherboard is also about $50 to $100 cheaper (e.g. Sabertooth Z77 for > i7 @ $244 vs Sabertooth 990FX for AMD CPUs at $197) http://www.graysonline.com When I'm buying new hardware I visit Grays Online. You can get entire systems for less than the cost of the CPUs you list. Sure they won't be as fast, but I'd rather buy a new system every year or so than wait years for a big upgrade. > as Russell suggested, a RAID-1 array is better/safer. but if you don't > need the extra terabyte of storage, 2x2TB drives is a lot cheaper than > the 2x3TB drives he suggested. http://www.tecs.com.au/shop/storage/desktop-sata-hard-drives.html?limit=30 At the above there's a Seagate 2TB disk for $119 and a Seagate 3TB disk for $139. Not a lot cheaper, only $20 for the extra TB. There's a WD Green 2TB disk for $99 and a WD Green 3TB disk for $159, so if you want the WD Green series then there's a significant price difference. But generally you won't want WD Green for a RAID array due to the head parking issues. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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Re: [luv-talk] New Computer System
by Russell Coker 24 Apr '13

24 Apr '13

On Mon, 22 Apr 2013, "Trent W. Buck" <trentbuck(a)gmail.com> wrote: > I assume you'd have a non-negligible amount of zlib CPU churn when > paging out to zram -- is that noticable? I suppose it is, but only > when you have pegged BOTH CPU and RAM. Using zram is a trade-off of CPU performance vs disk IO performance. As CPU performance has been increasing steadily at an exponential rate for the last 20 years and disk performance has been increasing at a slow linear rate over that period such a trade-off becomes increasingly beneficial. Pegging both CPU and RAM is something that's difficult to do given that running out of RAM results in processes being blocked on disk IO (regular file IO that's not in cache or swap). A quick test on an Intel T7500 CPU (which is far from the fastest CPU available today and wasn't even the fastest laptop CPU when I bought it) shows that gzip -9 on a 10MB file takes half a second of CPU time. While this is quite a bit of time (more than it would take to do a direct contiguous write of the same data) when you count random seeks for small access it's going to average a much higher rate than HDD access. Rates lower than 3MB/s are often seen on modern disks in real-world use due to seek overhead. Whether zram is better than SSD is another issue. With the Intel SSD I've tried the contiguous read and write speeds are quite a bit lower than that of hard disks and while the overall performance is a significant improvement over hard disks it's still not nearly as good as I'd hoped for. If SSD was as good as some people claim then zram might not offer much benefit. But with the 120G Intel SSDs I've tried there is plenty of scope for zram to boost performance. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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zram
by Russell Coker 24 Apr '13

24 Apr '13

There has been some discussion on luv-talk (which should have been on luv- main) about zram, a system that uses a compressed RAM disk for swap on Linux. I've enabled zram on one of my systems. I ran "free" on all the systems I run and found that only one had any significant swap use, that's a workstation with 8G of RAM and 512M of swap in use. I didn't bother enabling it on any other systems. I added "zram" to /etc/modules (modules that are loaded on boot on Debian). I created /etc/modprobe.d/zram.conf with the following contents: options zram num_devices=2 This gives two devices and it seems that you are expected to have one zram device for each CPU core. I'm not sure if this is really required but it doesn't seem to do any harm. To enable zram on boot I added the following to /etc/rc.local: echo 1073741824 > /sys/block/zram0/disksize echo 1073741824 > /sys/block/zram1/disksize mkswap /dev/zram0 mkswap /dev/zram1 swapon -p 100 /dev/zram0 swapon -p 100 /dev/zram1 The above sets each of the two devices to 1G of storage and enables them as swap space. I haven't yet rebooted the system to make sure that there are no errors in the above, but as it's what I types on the command-line it should work. Also I haven't tested zram extensively. Finally I'm running the Debian/Experimental 3.8 kernel. I don't know how it would work on other kernels. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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Re: [luv-main] Redundant network links.
by Russell Coker 23 Apr '13

23 Apr '13

Firstly I'm moving this to luv-main because it's about serious Linux networking issues. On Sun, 21 Apr 2013, Tony Langdon <vk3jed(a)gmail.com> wrote: > About to rebuild the network here after moving house. One issue I'm > contemplating is performance and redundancy. One part of the network > can't (easily) be reached by Cat 5/6, running cables t that part of the > house would be too messy at best. I have two ways I can bridge this gap > - Powerline Ethernet adapters, which have worked extremely well in the > past, or WiFi, using an access point in client bridge mode. > > Now the powerline adapters do work extremely well, with a rated speed of > 85 Mbps. I've never had an issue, except for the switchmode supply of > one laptop, which trashed the link (took a bit of detective work that > one!). The biggest weakness of these devices is that they can't be > battery backed up. If the mains goes down, so do they. http://etbe.coker.com.au/2010/08/04/clusters-dont-work/ I wrote the above blog post about my experience with clusters. Some of this applies to failover of links. One significant difference between a home network and a serious server network is that most of the functions of your home network don't matter much when you are asleep or away. Therefore a redundancy which involves you logging in as root and running a route command will work a lot better on a home network. Of course my experience is that having a sysadmin login as root and manually fail things over is better than any cluster software implementation I've seen, but that's another issue. > WiFi can be backed up, especially since a lot of the gear I have will > happily run off a 12V battery, and some of the systems on the far end > will be running off a battery backed DC supply. However, performance > with the WiFi solution isn't as good. > > Is there a way I can (easily and cheaply) arrange to run on the > powerline devices by default and fail over to WiFi, if the power goes down? How often does power go down anyway? -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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debian "experimental" kernels
by James Harper 21 Apr '13

21 Apr '13

Is anyone using kernels from Debian experimental? I needed something newer than 3.2.x (testing ceph but I'm getting kbyte/second write performance!) so I tried a 3.8.x kernel from Debian experimental but it just reboots with no indication of why (using serial console via bmc) James

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Invitation to connect on LinkedIn
by Peter Drake 21 Apr '13

21 Apr '13

LinkedIn ------------ Linux, I'd like to include you in my network to share updates and stay in touch. - Peter Peter Drake Teacher at Victoria University Melbourne Area, Australia Confirm that you know Peter Drake: https://www.linkedin.com/e/-yhvhf6-hfqhmow1-y/isd/12623853746/illMn13Y/?hs=… -- You are receiving Invitation to Connect emails. Click to unsubscribe: http://www.linkedin.com/e/-yhvhf6-hfqhmow1-y/AsY5QCVyLGMDpk6UevYY8mLJhvdwey… (c) 2012 LinkedIn Corporation. 2029 Stierlin Ct, Mountain View, CA 94043, USA.

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Video problems - NVidia/Nouveau
by Jason White 19 Apr '13

19 Apr '13

My desktop workstation has been encountering intermittent video issues, including illegible screen displays and cases in which the monitor doesn't respond at all after Linux is loaded. Rebooting the system always seems to fix it however. This isn't so much of a problem for me, as I have a vision impairment and use braille and speech output, but it is an issue when someone else wants to use the machine. The only relevant error I found in the kernel log is: Mar 20 15:05:58 jdc kernel: [23207.760016] [drm] nouveau 0000:40:00.0: DDC responded, but no EDID for DVI-I-2 (after turning the monitor off then back on, after which it still didn't display any video.) The video card in this machine has been replaced twice over the years, both times under warranty/service contract, and with the same model of card, so I have my suspicions. It's a very up to date Debian Sid system, kernel 3.2.0-4-amd64 #1 SMP Debian 3.2.39-2 x86_64 GNU/Linux I didn't find any relevant Debian bug reports. Obviously I want to know whether it's hardware or software, and if hardware, the card itself or something else.

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RAID, again
by James Harper 17 Apr '13

17 Apr '13

Now I have another RAID problem. Each disk is partitioned like: /dev/sd[abcd]1 - bios boot partition /dev/sd[abcd]2 - md0 - /boot (I believe grub can now see inside lvm but this config predates that) /dev/sdX3 - md1 - lvm - /root + others I have been progressively replacing disks. sdd was fine, sdc was fine, then I replaced sda to test that booting worked (changed bios to boot from sdb, added new sda, added to raid, etc) and that didn't work because I mucked up the gpt bios boot partition. Having fixed that, I rebooted to test booting again while md1 was still rebuilding onto sda3, and it drops into the initramfs shell on boot because mdadm first sees sda, then tries to add sd[bcd]3 but because each of those disks say that sda3 is not consistent the rebuild fails leaving just sda3 present as a 'spare' drive. In the initramfs console I just manually stop the array, add sd[bcd]3, then sda3, and it's all good again, but I didn't think this was the way it was supposed to work. On the most recent boot I zero'd the superblock of sda3 before re-adding it, thinking maybe it had picked up some bitrot somewhere along the way, but I'm not confident. Because the server is responsible for running backups and last night's backups didn't work because it was down, I'm not going to touch it again until tonight's backups are complete, but any hints on how to make this work smoother next time would be appreciated! And just to recap, rebooting a RAID comprising of /dev/sd[abcd]3, when /dev/sda3 is being rebuilt, results in a boot that drops into the initramfs shell because it appears that mdadm tries to add /dev/sda3 first then rejects the other 3 disks because they say /dev/sda3 is inconsistent (which it is). Thanks James

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spamassassin and detailed logs
by Russell Coker 17 Apr '13

17 Apr '13

spamd: result: . 1 - DKIM_ADSP_DISCARD,SPF_PASS,T_RP_MATCHES_RCVD,UNPARSEABLE_RELAY Currently I'm getting log entries like the above from SpamAssassin. spamd: result: . 1 - DKIM_ADSP_DISCARD=1,SPF_PASS=-1,T_RP_MATCHES_RCVD=1,UNPARSEABLE_RELAY=0 I want to see something like the above with numbers for each test so I can easily determine why the total was determined. I know that I can search through the SA configuration for each test, but this is time consuming and has the problem that the SA configuration might not do what I want. add_header all Status "_YESNO_, score=_SCORE_ required=_REQD_ tests=_TESTSSCORES_ autolearn=_AUTOLEARN_ version=_VERSION_" According to the below URL adding the above to local.cf should give the result I want. But on Debian/Wheezy it doesn't. Can anyone give me a pointer? As an aside I'm configuring my personal server on Debian/Wheezy and when I get it right I'll do it on a bigger server running CentOS 5. So if there are any relevant differences between Debian and CentOS in this regard I'd like to know about them. http://mail-archives.apache.org/mod_mbox/spamassassin- users/200703.mbox/%3C20070304222615.D13968(a)duane.dbq.yournetplus.com%3E Thanks. -- My Main Blog http://etbe.coker.com.au/ My Documents Blog http://doc.coker.com.au/

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