What is the difference between work conserving I/O scheduler and non-work conserving I/O scheduler? In a work-conserving mode, the scheduler must choose one of the pending requests, if any, to dispatch, even if the pending requests are far away from the current disk head position. The rationale for non-work-conserving schedulers, such as the anticipatory scheduler
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Tag: RAID
mkfs refuses to make filesystem with message “is apparently in use by the system; will not make a filesystem here!”
Posted onI have a disk from another server installed on a new server. However, when I try to make a filesystem on it, mkfs reports # mkfs -t ext4 /dev/sdd1 mke2fs 1.42.8 (20-Jun-2013) /dev/sdd1 is apparently in use by the system; will not make a filesystem here! This is a new disk to the new server.
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Which Checksum Tool on Linux is Faster?
Posted onIt is common practice to calculate the checksums for files to check its integrity. For large files, the checksum computation is slow. Now I am wondering why it is so slow and whether choosing another tool will be better. In this post, I try three common tools md5sum, sha1sum and crc32 to compute checksums on
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How to Clean RAID Signatures on Linux
Posted onRAID systems such as MegaRAID add signatures to disks to maintain the infomration on these didks. When we simply remove these disks and install them to another server, Linux on the new server may detect these RAID signature infomration and refuses to continue write to the disk. Here is one example that mkfs reports “apparently
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Making GPT Partition Table and Creating Partitions Using parted in Linux
Posted onMy best favorite disk partition table manipulation tools are cfdisk/fdisk on Linux. However, for large disks, cfdisk/fdisk (of the versions by this post is written) will just give up with a message suggesting GPT partition table format and using GNU parted like WARNING: The size of this disk is 6.0 TB (6001042391040 bytes). DOS partition
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How to Set Up RAID0 in MegaRAID BIOS with New Disks
Posted onThe LSI MegaRAID is widely used like in IBM x3620M3 servers. This post introduces the process with screenshots of how to configure the new disks and set up RAID0 in the MegaRAID BIOS for reference by other and myself. It is illustrated with one example by adding a new 2TB hard disk and creating a
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Colossus: Successor to the Google File System (GFS)
Posted onColossus is the successor to the Google File System (GFS) as mentioned in the paper on Spanner at OSDI 2012. Colossus is also used by spanner to store its tablets. The information about Colossus is slim compared with GFS which is published in the paper at SOSP 2003. There is still some information about Colossus
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Conferences on Cloud Computing 2012
Posted onThis post lists important conferences on Cloud Computing in year 2012. OSDI 2012 10th USENIX Symposium on Operating Systems Design and Implementation (OSDI ’12) October 8–10, 2012, Hollywood, CA “The tenth OSDI seeks to present innovative, exciting research in computer systems. OSDI brings together professionals from academic and industrial backgrounds in what has become a
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