From what I understand, the disk device has a queue that stores read/write requests from the linux kernel. What happens when the device doesn't drain the queue fast enough (i.e. overflows)?  Does this queue extend (logically) into DRAM?   can some requests be lost?
50787
I am programming a server and it seems like my number of connections is being limited since my bandwidth isn't being saturated even when I've set the number of connections to "unlimited".  How can I increase or eliminate a maximum number of connections that my Ubuntu Linux box can open at a time? Does the OS limit this, or is it the router or the ISP? Or is it something else?
4239
I've not used dd all that much, but so far it's not failed me yet. Right now, I've had a dd going for over 12 hours - I'm writing an image back to the disk it came from - and I'm getting a little worried, as I was able to dd from the disk to the image in about 7 hours.   I'm running OSX 10.6.6 on a MacBook with a Core 2 Duo at 2.1ghz/core with 4gb RAM. I'm reading from a .dmg on a 7200rpm hard drive (the boot drive), and I'm writing to a 7200rpm drive connected over a SATA-to-USB connector. I left the blocksize at default, and the image is about 160gb.  EDIT: And, after 14 hours of pure stress, the dd worked perfectly after all. Next time, though, I'm going to run it through pv and track it with strace. Thanks to everyone for all your help.
79900
I've tried to deal with this for days now with no luck. In this forum and also in other ones I can see a lot of discussion about this but none of the solutions have worked for me.  My current situation is that I've got some GBs "missing" that I can't free or find anywhere. I guess this is some kind of problem like memory leaks that only get fixed when rebooting, but I just would like to ask if someone has a better idea because there are currently a few customers on that server.  Here are some of the commands I've seen in other threads and my particular outputs:  df -h  Filesystem            Size  Used Avail Use% Mounted on /dev/sda1              19G   16G  1.8G  90% / tmpfs                 384M     0  384M   0% /lib/init/rw udev                   10M  1.2M  8.9M  12% /dev tmpfs                 384M     0  384M   0% /dev/shm   du -Pshx /* 2>/dev/null  4.8M    /bin 27M /boot 0   /cdrom 1.2M    /dev 8.8M    /emul 504M    /etc 4.0K    /grubconf 88K /home 60K /images 0   /initrd.img 147M    /lib 0   /lib32 0   /lib64 16K /lost+found 12K /media 4.0K    /mnt 4.4M    /opt 777M    /proc 57M /root 4.7M    /sbin 4.0K    /selinux 4.0K    /srv 0   /sys 4.0K    /tmp 332M    /usr 471M    /var 0   /vmlinuz   lsof +L1  (no output)   lsof | grep -i delete  (no output)   find / -size +50000 -exec ls -lah {} +;  -r-------- 1 root    root 777M 2015-07-21 06:19 /proc/kcore -rw------- 1 root    root  64M 2015-07-09 03:31 /sys/devices/pci0000:00/0000:00:06.0/0000:01:04.0/resource0 -rw-r----- 1 root    adm   49M 2015-07-21 06:19 /var/log/auth.log -rw-r----- 1 root    adm  174M 2015-07-19 06:25 /var/log/auth.log.1 -rw-rw---- 1 control mail 100M 2015-07-21 06:00 /var/mail/control   If you make the maths from du, for example, you get a few GBs, but nothing close to 16GB.  / is ext3.  OS is Debian 6.0  is there anything am I missing here?
58119
Is it possible to put the entire operating system on a ram disk? If I have 16 GB of RAM and it is an Intel Xeon. I don't have an SSD and my hard drive is killing my boot time. So can I just allocate some of my ram to work as if it were an SSD and install windows and vital software on it, to gain super fast speed. Or is it more trouble then its worth and would be better off just buying an SSD?
20723
If computer RAM was to be non volatile like other persistent storages, then there would be no such thing as boot up time. Then why is it not feasible to have a non volatile RAM module?
22958
An  has an .  The memory is . It has only about 1000 MHz DRAM frequency:      Could anyone provide a clue on why the RAM speed is so low?  Am I missing some fundamental understanding of the speed numbers?
92381
I'm going to install Linux on Lenovo B5400, which contains:   500GB Hybrid SSHD with a 8 GB SSD and 500 GB HDD   Designing partitions for my 2 Linux distros was quite easy before, when I had only HDD. I always had:   10GB for Linux distro (mounted as "/") 10GB for another distro (again "/"; for another distro; for testing purposes or to assure continuity when switching distros) 2GB for swap (used for both distros; no need to separate) 300GB+ for "/home" (used for both distros; different usernames eliminates possible conflicts)   It's simple, isn't it? I would like to keep this approach, but I know that SSD has its own specificity - it prefers to be read, continuous writing may affect its life span. I don't want to kill SSD in a year, so I would like to move some system partitions to HDD in order to protect SSD. As far as I know /tmp is one of often read&amp;written locations. How much space it needs? What else should be placed on HDD?  Or: how to design partitions to achieve exactly the same effect and to keep SSD as safe as possible?  I'd be grateful for your help.
119098
I started to get confused on how the hard disk operates, particularly in writing and reading data into its platters.  According to this article:    hard disks write data in a linear path (as what I presume). If so, what are sectors for?
5599
I'm getting the following output from top:  Cpu(s): 43.8%us, 32.5%sy,  4.8%ni,  2.0%id, 15.6%wa,  0.2%hi,  1.2%si,  0.0%st Mem:  16331504k total, 15759412k used,   572092k free,  4575980k buffers Swap:  4194296k total,   260644k used,  3933652k free,  1588044k cached   the output from iostat -xk 6 shows the following:  Device: rrqm/s   wrqm/s     r/s     w/s    rkB/s    wkB/s avgrq-sz avgqu-sz   await  svctm  %util sda       0.00   360.20   86.20  153.40  1133.60  2054.40    26.61     1.51    6.27   0.77  18.38 sdb       0.00     0.00    0.00    0.00     0.00     0.00     0.00     0.00    0.00   0.00   0.00 sdd      22.60   198.80   17.40   31.60   265.60   921.60    48.46     0.18    3.70   1.67   8.20 sdc      16.80   218.20   22.20   23.40   261.60   966.40    53.86     0.21    4.56   1.49   6.78   Based on the above it looks like something must be overloaded. But what?   Questions   If its not the harddisk or the CPU then what? It seems as though 15.6% of the CPU's time is spent waiting. What exactly could it be waiting for?
22912
iotop -a (accumulated I/O) on Linux shows after about 10 min. of browsing Internet:  Total DISK READ:       0.00 B/s | Total DISK WRITE:       0.00 B/s                  TID  PRIO  USER     DISK READ DISK WRITE&gt;  SWAPIN      IO    COMMAND            17330 be/4 wojdyr     1540.00 K     38.48 M  0.00 %  0.00 % firefox                 403 be/3 root          0.00 B     31.65 M  0.00 %  0.06 % [jbd2/sda5-8]         17276 be/4 wojdyr      800.00 K     31.06 M  0.00 %  0.00 % firefox               17329 be/4 wojdyr        0.00 B     20.96 M  0.00 %  0.00 % firefox               31896 idle wojdyr        0.00 B   1200.00 K  0.00 %  0.00 % virtuoso-~.ini +wait  31924 be/4 wojdyr        0.00 B   1064.00 K  0.00 %  0.00 % akonadi_n~ail_feeder  18959 be/4 wojdyr        0.00 B    796.00 K  0.00 %  0.01 % firefox   I'm quite surprised by the amount of data written to disk. I turned off to-disk caching, but it didn't make notable difference. I turned off block-reported-attack-sites/web-forgeries -- nothing changed.  Is this rate of writing to disk normal in Firefox (10.0.1)? It quickly exceeds the total size of my firefox profile.  Looking at modification times of files in the firefox profile I see that a few files are modified very often:  cookies.sqlite{-wal,-shm} sessionstore.js places.sqlite{-wal,-shm} permissions.sqlite   Is there something wrong with my system or configuration, or is it typical for FF?  I don't like this pointless writing to (SSD) disk. Can I do something about it?  EDIT: I've found  how to relocate the entire Firefox profile to RAM. It reduced almost to zero data written by firefox during session. (I know this is a bit paranoid and probably not worth the hassle.)
55303
My laptop has recently started to become a bit unreliable, and for some reason I started to suspect that my HDD was starting to fail. After a bit of hunting on the internet, I found Ubuntu's Disk Utility in the System menu and ran the long SMART diagnostics from this.  However, since the documentation for Disk Utility is very poor (palimpsest?), I'm not sure how to interpret the results:    For example, the Read Error Rate is over 50 million (!), yet the Assessment is rated "Good".   So would someone mind explaining to me how to interpret the results of these tests (especially the Normalized, Worst, Threshold and Value numbers)? And maybe tell me what they think of the results I got for my HDD? (Thanks)
110604
Recently, I put more ram into my server and now I have got a total of 24GB of RAM. Originally, I setup the OS to have a 2GB swap size.  /dev/sdc1               1         281     2257101   82  Linux swap / Solaris /dev/sdc2   *         282       60801   486126900   83  Linux   2GB is allocated for swap currently, but reading around it seems it is not much. For a system with 24GB, I am thinking to allocate at least 10GB of swap.   My questions is: Can I do it while the OS is running? Do I have to reinstall?  I am using OpenSuse 11.3
54836
Under certain conditions, the Linux kernel may become tainted. For example, loading a proprietary video driver into the kernel taints the kernel. This condition may be visible in system logs, kernel error messages (oops and panics), and through tools such as lsmod, and remains until the system is rebooted.  What does this mean? Does it affect my ability to use the system, and how might it affect my support options?
59594
I'm planing an age replacement policy for our storage and servers. Most of them are for DBs and some for images (static content) so yes, they have an huge I/O everytime.  Also, we use Samsung 840 Pro SSDs for the RAID Controllers (PERC H700i) as CacheCade.  Are you guys managing the replacement of old hard drives and solid state drives?
53232
Is there a (technical or practical) limit to how large you can configure the maximum number of open files in Linux?  Are there some adverse effects if you configure it to a very large number (say 1-100M)?  I'm thinking server usage here, not embedded systems.  Programs using huge amounts of open files can of course eat memory and be slow, but I'm interested in adverse effects if the limit is configured much larger than necessary (e.g. memory consumed by just the configuration).
114017
A lot of strange loop devices appear in my Kubuntu OS.      [translation:     Hard disk 107.4GB     Hard disk 487.0GB     Loop Device     Hard Disk 4.0GB     Loop Device     Loop Device     Loop Device     Loop Device     Victor Disk]   Can anybody tell me what it is? .
39750
I've copied a large file to a USB disk mounted on a Linux system with async. This returns to a command prompt relatively quickly, but when I type sync, of course, it all has to go to disk, and that takes a long time.  I understand that it's going to be slow, but is there somewhere where I can watch a counter go down to zero? Watching buffers in top doesn't help.