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Operating Systems AIX IBM AIX Internal HDD vs SAN HDD and Oracle Post 302883312 by rbatte1 on Monday 13th of January 2014 09:11:47 AM
Old 01-13-2014
We have seen differences in performance of a similar scale and nature.

Internal/local disk is managed by your server and it is responsible for all the real IO, writing the bits to the disk controllers and getting the acknowledgement when the update is made to the brown-spinning part.

With SAN storage, the request by your OS to write data is accepted and confirmed by the SAN before the data is really written to disk. It's written to the SAN cache, but as far as your OS is concerned, then transaction is complete and processing can continue.


A SAN disk array will have a large cache dedicated to holding write requests and flushing them to real disk in large IO writes. This is why all SAN disk arrays will have batteries to keep the cache alive in the event of a power failure. This is in addition to any UPS you may have in place. A SAN shutdown can also be done in two ways roughly described as immediate and controlled. In the controlled shutdown, the cache is flushed and the SAN disk is consistent. An Immediate shutdown does not flush the cache and is quicker. It has no difference for the actual data stored unless the battery fails or is replaced.


As to a way to measure it, I suppose you are into creating a large complex file and copying it about a few times. By complex, I mean something that compression software will not easily deal with. My way to do this (mainly for testing FTP speed) is to tar up some large files and compress them, then append them a few times to get the size big enough.

If your hardware can support it, then it can be beneficial to have everything as SAN storage, including the OS and paging space. The limitation then becomes the connection speed to the SAN.

If you replicate your SAN to another site, then this takes care of updates to the boot disks / rootvg / vg00 (whatever you want to call it) that may affect the DR position. Of course, the IP address will be replicated so you have to handle that along with a process to use perhaps different hardware at the remote site.

It is, however no substitute for backups as errors / corruption will also be replicated honestly.



I hope that this helps.

Robin
Liverpool/Blackburn
UK
 

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gnutls_x509_crt_get_subject_alt_name(3) 			      gnutls				   gnutls_x509_crt_get_subject_alt_name(3)

NAME
gnutls_x509_crt_get_subject_alt_name - API function SYNOPSIS
#include <gnutls/x509.h> int gnutls_x509_crt_get_subject_alt_name(gnutls_x509_crt_t cert, unsigned int seq, void * san, size_t * san_size, unsigned int * critical); ARGUMENTS
gnutls_x509_crt_t cert should contain a gnutls_x509_crt_t structure unsigned int seq specifies the sequence number of the alt name (0 for the first one, 1 for the second etc.) void * san is the place where the alternative name will be copied to size_t * san_size holds the size of san. unsigned int * critical will be non-zero if the extension is marked as critical (may be null) DESCRIPTION
This function retrieves the Alternative Name (2.5.29.17), contained in the given certificate in the X509v3 Certificate Extensions. When the SAN type is otherName, it will extract the data in the otherName's value field, and GNUTLS_SAN_OTHERNAME is returned. You may use gnutls_x509_crt_get_subject_alt_othername_oid() to get the corresponding OID and the "virtual" SAN types (e.g., GNUTLS_SAN_OTHERNAME_XMPP). If an otherName OID is known, the data will be decoded. Otherwise the returned data will be DER encoded, and you will have to decode it yourself. Currently, only the RFC 3920 id-on-xmppAddr SAN is recognized. RETURNS
the alternative subject name type on success, one of the enumerated gnutls_x509_subject_alt_name_t. It will return GNUTLS_E_SHORT_MEM- ORY_BUFFER if san_size is not large enough to hold the value. In that case san_size will be updated with the required size. If the cer- tificate does not have an Alternative name with the specified sequence number then GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE is returned. REPORTING BUGS
Report bugs to <bug-gnutls@gnu.org>. General guidelines for reporting bugs: http://www.gnu.org/gethelp/ GnuTLS home page: http://www.gnu.org/software/gnutls/ COPYRIGHT
Copyright (C) 2012 Free Software Foundation, Inc.. Copying and distribution of this file, with or without modification, are permitted in any medium without royalty provided the copyright notice and this notice are preserved. SEE ALSO
The full documentation for gnutls is maintained as a Texinfo manual. If the info and gnutls programs are properly installed at your site, the command info gnutls should give you access to the complete manual. As an alternative you may obtain the manual from: http://www.gnu.org/software/gnutls/manual/ gnutls 3.1.15 gnutls_x509_crt_get_subject_alt_name(3)
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