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| abstract:caviness:filesystems:lustre [2020-05-29 13:36] – frey | abstract:caviness:filesystems:lustre [2020-05-29 16:17] – frey |
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| The Caviness cluster contains multiple //Object Storage Targets// (OSTs) in each rack that each contain many hard disks. For example, ''ost0'' contains 10 SATA hard disks (8 TB each, 1 hot spare) managed as a ZFS storage pool with an SSD acting as a read cache for improved performance: | The Caviness cluster contains multiple //Object Storage Targets// (OSTs) in each rack that each contain many hard disks. For example, ''ost0'' contains 10 SATA hard disks (8 TB each, 1 hot spare) managed as a ZFS storage pool with an SSD acting as a read cache for improved performance: |
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| {{ :abstract:caviness:filesystems:caviness-lustre-oss_ost.png?400 |Example image of Caviness Lustre OSS/OST. }} | {{ :abstract:caviness:filesystems:caviness-lustre-oss_ost.png?400 |Example image of Caviness Lustre OSS/OST. }} |
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| For large files or files that are internally organized as "records((A //record// consists of a fixed-size sequence of bytes; the //i//-th record exists at an easily calculated offset within the file.))" i/o performance can be further improved by //striping// the file across multiple OSTs. Striping divides a file into a set of sequential, fixed-size chunks. The stripes are distributed round-robin to //N// unique Lustre objects -- and thus on //N// unique OSTs. For example, consider a 13 MiB file: | For large files or files that are internally organized as "records((A //record// consists of a fixed-size sequence of bytes; the //i//-th record exists at an easily calculated offset within the file.))" i/o performance can be further improved by //striping// the file across multiple OSTs. Striping divides a file into a set of sequential, fixed-size chunks. The stripes are distributed round-robin to //N// unique Lustre objects -- and thus on //N// unique OSTs. For example, consider a 13 MiB file: |
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| {{ lustre-striping.png?500 |Lustre striping.}} | {{ :abstract:caviness:filesystems:caviness-lustre-striping.png?500 |Lustre striping.}} |
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| Without striping, all 13 MiB of the file resides in a single object on ''OST0001'' (see (a) above). All i/o with respect to this file is handled by ''OSS1''; appending 5 MiB to the file will grow the object to 18 MiB. | Without striping, all 13 MiB of the file resides in a single object on ''OST0001'' (see (a) above). All i/o with respect to this file is handled by ''OSS1''; appending 5 MiB to the file will grow the object to 18 MiB. |