RAID0 "stripes" the data across the three actuators you have and the stripe size (that's official RAID speak) is the minimum allocation. So if the stripe is 2k then the first 2k bytes of a file is written to the first drive, the next 2k to the second drive, and the third 2k to the third drive. It then goes back to the first drive, and so on.
So it's not difficult to see that writing lots of small files will give unpredictable results respecially if they're less than 2k each. Also, read requests can only be satisfied be reading the drive(s) where the files were written.
So your results are misleading.
If you have a desire to test this then you need to do something like......
Create a 4GB file on (ideally) an internal drive not part of this RAID0 array. Kick all the users off if you can and then copy this 4GB to the RAID filesystem and take your measurements whilst that's going on. It won't be precise but should give you a better set of figures.
True, this will be off by the overhead of /dev/zero, wouldn't that be negligible given the bandwidth of disks and the memory interface (which are apart some orders of magnitude)?
First of all, my problem does not happen any more. I created the raid with sdb, sdc and sdd on April 11 at 09:35.
Until 11:32, sdd was very busy, then until 14:51, sdc was very busy.
Since then (3 days), the 3 disks are always under the same moderate load altogether (0-20%). The server is used by 5 graphic designers manipulating quite large files (100M-2G).
I ran some tests and the results leave me quite puzzled. So I created simultaneously 10 files. 1GB each. But all the load went on sda. Leaving sdb, sdc and sdd with a moderate 20% load.
The command:
Code:
for i in {1..10}; do
file=$(mktemp /galaxy/XXXXXXX)
echo $file >> /galaxy/dd.files
dd if=/dev/zero of=$file bs=1G count=1 &
echo $! >> /galaxy/dd.pids
done
Hello,
On 4/20/2018, we performed a disk replacement on our IBM 8202 P7 server. After the disk was rebuilt, the SAS Disk Array sissas0 showed a status of degraded. However, the pdisks in the array all show a status of active.
We did see a message in errpt. DISK ARRAY PROTECTION SUSPENDED.
... (3 Replies)
Hello,
On 4/20/2018, we performed a disk replacement on our IBM 8202 P7 server. After the disk was rebuilt, the SAS Disk Array sissas0 showed a status of degraded. However, the pdisks in the array all show a status of active.
We did see a message in errpt. DISK ARRAY PROTECTION SUSPENDED.
... (1 Reply)
HI:
I have a DUAL redundant system running in HP-UX 10.20 ( 2 servers)
Both servers share an external SCSI disk array. Both server runs a Data base wich uses the disk array to write the data, and that is the way they share the information.
The way that the servers see the disk array, is like... (1 Reply)
So I have 2 solaris sun servers one with a disk array with 14 drives which I need to move to the other server. How do I move the disk array configured as a Raid 5 to another server without losing data? So far I know I'll connect the drive, run devfsadm, use format to verify the server see's... (5 Replies)
I have read anecdotes about people installing RAID0 (RAID - Wikipedia, the free encyclopedia) on some of their machines because it gives a performance boost. Because bandwidth on the motherboard is limited, can someone explain exactly why it should be faster? (7 Replies)
Hi,
I have the Lacie Big Disk, which is a external hard drive enclosure in a hardware RAID0 array of 2x250GB disks. The RAID controller seems to have died, leaving me with 2 working hard drives but no way to get the data. I tried hooking the drives up to a windows machine and using Raid... (4 Replies)
I have a 3510 disk array attached to a T2000 server.
The dmesg command shows disk error as follows and is generated a couple of times during the day
Aug 18 03:35:51 myserver SUNWscsdMonitor: <rctrl6042> Standard General Event, CHL:2 ID:22 Drive NOTICE: Drive Recovered Error - 5F8E1F... (1 Reply)
I am new to the unix world. I have SunBlade 100 and A1000 Disk storage array with 12 Hard drives. I used SCSI card and SCSI cables to connect. When I do the format command,I can see disk storage as one disk instead of 12 disks as below. Could anybody can explain why?
What should I do in order... (1 Reply)
04-12-2016
