That will be inaccurate because of cache... stuff written to disk just gets shoved into memory until the disk's ready. 30 gigs would probably fill the cache, but still, there's better ways that don't involve waiting for 30 gigs of data to be written.
Linux usually has the hdparm command. It has read tests that take just a few seconds:
There's no equivalent write-speed test but, for a traditional hard disk, read speed and write speed should be about the same.
If a file size increases in Linux/UNIX to say in GB's then will there be a decrease in write speed.
I mean will it take more time to write to a large file then to a small one??
Please clarify?
Thanks in advance (2 Replies)
I analysed disk performance with blktrace and get some data:
read:
8,3 4 2141 2.882115217 3342 Q R 195732187 + 32
8,3 4 2142 2.882116411 3342 G R 195732187 + 32
8,3 4 2144 2.882117647 3342 I R 195732187 + 32
8,3 4 2145 ... (1 Reply)
Hi,
We have smb client running on two of the linux boxes and smb server on another linux system. During a backup operation which uses smb, read of a file was allowed while write to the same file was going on.Also simultaneous writes to the same file were allowed.Following are the settings in the... (1 Reply)
Would simply like to write data (no audio) to a CD/RW disk. The disk drive states CD/RW on the front but don't know for sure if the software is configured to recognize it as a writable disk. I can read/move data from the disk to the hard drive with no issue from the disk. Any help in this... (4 Replies)
I am now on Kernel 2.6.32-26
For me 16x CD write speed is okay.
I have old hardware which was able to write DVDs at 1x, back in previous linux version.
Now, I dont get speed of less than 4x.
Tested on k3b, xfburn, and brasero. But all start at bottom 4x write speed. k3b forced back to... (0 Replies)
Hi,
I went to a computer store and the salesman sold me a SATA cable and told me that all SATA cables are the same. Another salesman at a different store told me a cable rated for SATA 2, which I bought, MIGHT work as well as one rate for SATA 3 but it is not guaranteed. I decided to run a... (3 Replies)
hi all:
as we know , when usb flash disk plug in and aotu mounted , the default permission of the usb flash disk is 700. that means others have no permission . the question: how to make others have read/write permission when the aotu mounted usb flash disk pluge in ? thanks !! (0 Replies)
Hi,
We have two servers in scenario (vmsoldot01 is Oracle VM with Linux and tldtppod15 is physical Linux server). One NAS share is mounted on both servers with similar permissions and access. But READ speed is too bad on virtual in comparison to physical server.
While trying to diagnose this, I... (2 Replies)
Hello All,
I am building a real time parser for a log file in my application.
The log file is continuously written at a very fast pace and gets rolled over every 10 minutes.
I have measured the speed and observed that around 1000 lines are written to it every second, each line about 30-40... (7 Replies)
Discussion started by: cool.aquarian
7 Replies
LEARN ABOUT BSD
ram
RAM(4) Kernel Interfaces Manual RAM(4)NAME
ram - ram disk driver
SYNOPSIS
/sys/conf/SYSTEM:
NRAM ram_size # RAM disk size (512-byte blocks)
major device number(s):
block: 3
minor device encoding:
must be zero (0)
DESCRIPTION
The ram pseudo-device provides a very fast extended memory store. It's use is intended for file systems like /tmp and applications which
need to access a reasonably large amount of data quickly.
The amount of memory dedicated to the ram device is controlled by the NRAM definition in units of 512-byte blocks. This is also patchable
in the system binary through the variable ram_size (though a patched system would have to be rebooted before any change took effect; see
adb(1)). This makes it easy to test the effects of different ram disk sizes on system performance. It's important to note that any space
given to the ram device is permanently allocated at system boot time. Dedicating too much memory can adversely affect system performance
by forcing the system to swap heavily as in a memory poor environment.
The block file accesses the ram disk via the system's buffering mechanism through a buffer sharing arrangement with the buffer cache. It
may be read and written without regard to physical disk records. There is no `raw' interface since no speed advantage is gained by such an
interface with the ram disk.
DISK SUPPORT
The ram driver does not support pseudo-disks (partitions). The special files refer to the entire `drive' as a single sequentially
addressed file.
A typical use for the ram disk would be to mount /tmp on it. Note that if this arrangement is recorded in /etc/fstab then /etc/rc will
have to be modified slightly to do a mkfs(8) on the ram disk before the standard file system checks are done.
FILES
/dev/ram block file
/dev/MAKEDEV script to create special files
/dev/MAKEDEV.local script to localize special files
SEE ALSO hk(4), ra(4), rl(4), rk(4), rp(4), rx(4), si(4), xp(4)dtab(5), autoconfig(8)DIAGNOSTICS
ram: no space. There is not enough memory to allocate the space needed by the ram disk. The ram disk is disabled. Any attempts to access
it will return an error.
ram: not allocated. No memory was allocated to the ram disk and an attempt was made to open it. Either not enough memory was available at
boot time or the kernel variable ram_size was set to zero.
BUGS
The ram driver is only available under 2.11BSD.
3rd Berkeley Distribution Januray 27, 1996 RAM(4)