Recently I have done some informal disk performance test on my newly arrived workstations. (copy a 1GB text file on the same file system).<\/p>\n
On a Dell Precsion T3500 with Linux software RAID1 of 2x500GB SATA disk with AHCI enabled :<\/p>\n
[root@gsx42 disk1]# time cp a b On our busy mail server with PERC6i+ 2x15krpm SAS disk<\/p>\n [root@server mail]# time cp a b It seems that the R\/W performance of our PERC6i+SAS disk is not very satisfactory when compared to our new\u00a0 workstation though the mail server is much busier. After some research on google, I added the below parameter : blockdev –setra 16384 \/dev\/drive. The original readahead buffer for Linux is 128k, I changed this to 8M and redo the test :<\/p>\n root@server mail]# time cp a b A nearly double in performance!! I also note that this readahead buffer is only useful in sequential read of large files. This may not be useful for lots of random access of small blocks of data. However, for our mail server, it need to handle lot of large mailboxes so this should be useful. And for Vmware server hosting the vms in local storage, this parameter will be useful too.<\/p>\n Useful references :
\nreal\u00a0\u00a0 \u00a00m4.499s
\nuser\u00a0\u00a0 \u00a00m0.054s
\nsys\u00a0\u00a0 \u00a00m1.367s<\/span><\/p>\n
\nreal\u00a0\u00a0\u00a0 0m57.504s
\nuser\u00a0\u00a0\u00a0 0m0.209s
\nsys\u00a0\u00a0\u00a0\u00a0 0m2.859s<\/span><\/p>\n
\nreal 0m36.426s
\nuser 0m0.398s
\nsys 0m2.673s<\/span><\/p>\n
\n1. http:\/\/webcms.ba.infn.it\/cms-software\/cms-grid\/index.php\/Main\/TuningDiskServers<\/a><\/p>\n