MFV r319742: 8056 zfs send size estimate is inaccurate for some zvols
illumos/illumos-gate@0255edcc85
0255edcc85
https://www.illumos.org/issues/8056
The send size estimate for a zvol can be too low, if the size of the record
headers (dmu_replay_record_t's) is a significant portion of the size.
This is typically the case when the data is highly compressible, especially
with embedded blocks.
The problem is that dmu_adjust_send_estimate_for_indirects() assumes that
blocks are the size of the "recordsize" property (128KB).
However, for zvols, the blocks are the size of the "volblocksize" property
(8KB). Therefore, we estimate that there will be 16x less record headers than
there really will be.
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Pavel Zakharov <pavel.zakharov@delphix.com>
Approved by: Robert Mustacchi <rm@joyent.com>
Author: Paul Dagnelie <pcd@delphix.com>
MFC after: 3 weeks
This commit is contained in:
commit
ae5ec64b88
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=320238
@ -1140,10 +1140,17 @@ dmu_adjust_send_estimate_for_indirects(dsl_dataset_t *ds, uint64_t uncompressed,
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*/
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uint64_t recordsize;
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uint64_t record_count;
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objset_t *os;
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VERIFY0(dmu_objset_from_ds(ds, &os));
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/* Assume all (uncompressed) blocks are recordsize. */
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err = dsl_prop_get_int_ds(ds, zfs_prop_to_name(ZFS_PROP_RECORDSIZE),
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&recordsize);
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if (os->os_phys->os_type == DMU_OST_ZVOL) {
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err = dsl_prop_get_int_ds(ds,
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zfs_prop_to_name(ZFS_PROP_VOLBLOCKSIZE), &recordsize);
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} else {
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err = dsl_prop_get_int_ds(ds,
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zfs_prop_to_name(ZFS_PROP_RECORDSIZE), &recordsize);
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}
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if (err != 0)
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return (err);
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record_count = uncompressed / recordsize;
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@ -1212,6 +1219,10 @@ dmu_send_estimate(dsl_dataset_t *ds, dsl_dataset_t *fromds,
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err = dmu_adjust_send_estimate_for_indirects(ds, uncomp, comp,
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stream_compressed, sizep);
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/*
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* Add the size of the BEGIN and END records to the estimate.
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*/
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*sizep += 2 * sizeof (dmu_replay_record_t);
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return (err);
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}
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