On Wed, Feb 10, 2021 at 8:31 AM Marcelo <raxidex@xxxxxxxxx> wrote: > > Hello all! > > We have a cluster where there are HDDs for data and NVMEs for journals and > indexes. We recently added pure SSD hosts, and created a storage class SSD. > To do this, we create a default.rgw.hot.data pool, associate a crush rule > using SSD and create a HOT storage class in the placement-target. The > problem is when we send an object to use a HOT storage class, it is in both > the STANDARD storage class pool and the HOT pool. > > STANDARD pool: > # rados -p default.rgw.buckets.data ls > d86dade5-d401-427b-870a-0670ec3ecb65.385198.4_LICENSE > > # rados -p default.rgw.buckets.data stat > d86dade5-d401-427b-870a-0670ec3ecb65.385198.4_LICENSE > default.rgw.buckets.data/d86dade5-d401-427b-870a-0670ec3ecb65.385198.4_LICENSE > mtime 2021-02-09 14: 54: 14.000000, size 0 > > > HOT pool: > # rados -p default.rgw.hot.data ls > d86dade5-d401-427b-870a-0670ec3ecb65.385198.4__shadow_.rmpla1NTgArcUQdSLpW4qEgTDlbhn9f_0 > > > # rados -p default.rgw.hot.data stat > d86dade5-d401-427b-870a-0670ec3ecb65.385198.4__shadow_.rmpla1NTgArcUQdSLpW4qEgTDlbhn9f_0 > default.rgw.hot.data/d86dade5-d401-427b-870a-0670ec3ecb65.385198.4__shadow_.rmpla1NTgArcUQdSLpW4qEgTDlbhn9f_0 > mtime 2021-02-09 14: 54: 14.000000, size 15220 > > The object itself is in the HOT pool, however it creates this other object > similar to an index in the STANDARD pool. Monitoring with iostat we noticed > that this behavior generates an unnecessary IO on disks that do not need to > be touched. > > Why this behavior? Are there any ways around it? this object in the STANDARD pool is called the 'head object', and it holds the s3 object's metadata - including an attribute that says which storage class the object's data is in when an S3 client downloads the object with a 'GET /bucket/LICENSE' request, it doesn't specify the storage class. so radosgw has to find its head object in a known location (the bucket's default storage class pool) in order to figure out which pool holds the object's data > > Thanks, Marcelo > _______________________________________________ > ceph-users mailing list -- ceph-users@xxxxxxx > To unsubscribe send an email to ceph-users-leave@xxxxxxx > _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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