HP-UX VxFS tuning and performance - filibeto.org
HP-UX VxFS tuning and performance - filibeto.org HP-UX VxFS tuning and performance - filibeto.org
30 VxFS ioctl() options Cache advisories While the mount options allow you to change the cache advisories on a per-file system basis, the VX_SETCACHE ioctl() allows an application to change the cache advisory on a per-file basis. The following options are available with the VX_SETCACHE ioctl: VX_RANDOM - Treat read as random I/O and do not perform read ahead VX_SEQ - Treat read as sequential and perform maximum amount of read ahead VX_DIRECT - Bypass the buffer cache. All I/O to the file is synchronous. The application buffer must be aligned on a word (4 byte) address, and the I/O must begin on a block (1024 KB) boundary. VX_NOREUSE - Invalidate buffer immediately after use. This option is useful for data that is not likely to be reused. VX_DSYNC - Data is written synchronously, but the file‟s timestamps in the inode are not flushed to disk. This option is similar to using the O_DSYNC flag when opening the file. VX_UNBUFFERED - Same behavior as VX_DIRECT, but updating the file size in the inode is done asynchronously. VX_CONCURRENT - Enables concurrent I/O on the specified file. See the manpage vxfsio(7) for more information. HP OnLineJFS product is required to us the VX_SETCACHE ioctl(). Allocation policies The VX_SETEXT ioctl() passes 3 parameters: a fixed extent size to use, the amount of space to reserve for the file, and an allocation flag defined below. VX_NOEXTEND - write will fail if an attempt is made to extend the file past the current reservation VX_TRIM - trim the reservation when the last close of the file is performed VX_CONTIGUOUS - the reservation must be allocated in a single extent VX_ALIGN - all extents must be aligned on an extent-sized boundary VX_NORESERVE - reserve space, but do not record reservation space in the inode. If the file is closed or the system fails, the reservation is lost. VX_CHGSIZE - update the file size in the inode to reflect the reservation amount. This allocation does not initialize the data and reads from the uninitialized portion of the file will return unknown contents. Root permission is required. VX_GROWFILE - update the file size in the inode to reflect the reservation amount. Subsequent reads from the uninitialized portion of the file will return zeros. This option creates Zero Fill On Demand (ZFOD) extents. Writing to ZFOD extents negates the benefit of concurrent I/O. Reserving file space insures that you do not run out of space before you are done writing to the file. The overhead of allocating extents is done up front. Using a fixed extent size can also reduce fragmentation. The setext(1M) command can also be used to set the extent allocation and reservation policies for a file. See the manpage vxfsio(7) and setext(1M) for more information. HP OnLineJFS product is required to us the VX_SETEXT ioctl().
Patches Performance problems are often resolved by patches to the VxFS subsystem, such as the patches for the VxFS read ahead issues on HP-UX 11i v3. Be sure to check the latest patches for fixes to various performance related problems. Summary There is no single set of values for the tunable to apply to every system. You must understand how your application accesses data in the file system to decide which options and tunables can be changed to maximize the performance of your file system. A list of VxFS tunables and options discussed in this paper are summarized below. Table 6. List of VxFS tunables and options newfs mkfs bsize logsize version Mount Option blkclear datainlog nodatainlog mincache convosync cio remount tmplog delaylog log logiosize tranflush noatime nomtime qio File system tunables read_pref_io read_nstream read_ahead write_pref_io write_nstream max_buf_data_size max_direct_iosz discovered_direct_iosz max_diskq write_throttle initial_extent_size max_seqio_extent_size qio_cache_enable System wide tunables nbuf bufpages dbc_max_pct dbc_min_pct filecache_min filecache_max fcache_fb_policy vxfs_bc_bufhwm vx_ninode vxfs_ifree_timelag per-file attributes VX_SETCACHE VX_SETEXT 31
- Page 1 and 2: HP-UX VxFS tuning and performance T
- Page 3 and 4: Understanding VxFS In order to full
- Page 5 and 6: File system reorganization attempts
- Page 7 and 8: Read ahead with VxVM stripes The de
- Page 9 and 10: Figure 4. Flush behind As data is w
- Page 11 and 12: The read flush behind feature has t
- Page 13 and 14: Note The OnlineJFS license is requi
- Page 15 and 16: Concurrent I/O The main problem add
- Page 17 and 18: Zero Filled On Demand (ZFOD) extent
- Page 19 and 20: Table 3. Default intent log size FS
- Page 21 and 22: Using datainlog has no affect on no
- Page 23 and 24: Table 4. Intent log flush behavior
- Page 25 and 26: ead_ahead The default read_ahead va
- Page 27 and 28: Unified File Cache on HP-UX 11i v3
- Page 29: Note When setting vx_ninode to redu
Patches<br />
Performance problems are often resolved by patches to the <strong>VxFS</strong> subsystem, such as the patches for<br />
the <strong>VxFS</strong> read ahead issues on <strong>HP</strong>-<strong>UX</strong> 11i v3. Be sure to check the latest patches for fixes to various<br />
<strong>performance</strong> related problems.<br />
Summary<br />
There is no single set of values for the tunable to apply to every system. You must underst<strong>and</strong> how<br />
your application accesses data in the file system to decide which options <strong>and</strong> tunables can be<br />
changed to maximize the <strong>performance</strong> of your file system. A list of <strong>VxFS</strong> tunables <strong>and</strong> options<br />
discussed in this paper are summarized below.<br />
Table 6. List of <strong>VxFS</strong> tunables <strong>and</strong> options<br />
newfs<br />
mkfs<br />
bsize<br />
logsize<br />
version<br />
Mount<br />
Option<br />
blkclear<br />
datainlog<br />
nodatainlog<br />
mincache<br />
convosync<br />
cio<br />
remount<br />
tmplog<br />
delaylog<br />
log<br />
logiosize<br />
tranflush<br />
noatime<br />
nomtime<br />
qio<br />
File system<br />
tunables<br />
read_pref_io<br />
read_nstream<br />
read_ahead<br />
write_pref_io<br />
write_nstream<br />
max_buf_data_size<br />
max_direct_iosz<br />
discovered_direct_iosz<br />
max_diskq<br />
write_throttle<br />
initial_extent_size<br />
max_seqio_extent_size<br />
qio_cache_enable<br />
System wide<br />
tunables<br />
nbuf<br />
bufpages<br />
dbc_max_pct<br />
dbc_min_pct<br />
filecache_min<br />
filecache_max<br />
fcache_fb_policy<br />
vxfs_bc_bufhwm<br />
vx_ninode<br />
vxfs_ifree_timelag<br />
per-file attributes<br />
VX_SETCACHE<br />
VX_SETEXT<br />
31
Change language